CA1332740C - Laterally fluorinated 4- cyanophenyl and 4'- cyanobiphenyl bensoates - Google Patents
Laterally fluorinated 4- cyanophenyl and 4'- cyanobiphenyl bensoatesInfo
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- CA1332740C CA1332740C CA000591980A CA591980A CA1332740C CA 1332740 C CA1332740 C CA 1332740C CA 000591980 A CA000591980 A CA 000591980A CA 591980 A CA591980 A CA 591980A CA 1332740 C CA1332740 C CA 1332740C
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C255/00—Carboxylic acid nitriles
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K19/00—Liquid crystal materials
- C09K19/04—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit
- C09K19/06—Non-steroidal liquid crystal compounds
- C09K19/08—Non-steroidal liquid crystal compounds containing at least two non-condensed rings
- C09K19/10—Non-steroidal liquid crystal compounds containing at least two non-condensed rings containing at least two benzene rings
- C09K19/20—Non-steroidal liquid crystal compounds containing at least two non-condensed rings containing at least two benzene rings linked by a chain containing carbon and oxygen atoms as chain links, e.g. esters or ethers
- C09K19/2007—Non-steroidal liquid crystal compounds containing at least two non-condensed rings containing at least two benzene rings linked by a chain containing carbon and oxygen atoms as chain links, e.g. esters or ethers the chain containing -COO- or -OCO- groups
Abstract
ABSTRACT
LATERALLY FLUORINATED 4- CYANOPHENYL AND 4'- CYANOPHENYL BENZOATES.
Novel compounds of formula I:
Formula I
in which R is R1, R1O or R1COO, where R1 is C1-12 alkyl, n and m are 0 or 1 provided that (n + m) is 0 or 1, each a, b, c and d are independently 0 or 1, provided (a + b + c + d) is not zero, but excluding the case where a and b are O and m is O and one of c or de is O are described, being useful constituents of nematic liquid crystal materials.
LATERALLY FLUORINATED 4- CYANOPHENYL AND 4'- CYANOPHENYL BENZOATES.
Novel compounds of formula I:
Formula I
in which R is R1, R1O or R1COO, where R1 is C1-12 alkyl, n and m are 0 or 1 provided that (n + m) is 0 or 1, each a, b, c and d are independently 0 or 1, provided (a + b + c + d) is not zero, but excluding the case where a and b are O and m is O and one of c or de is O are described, being useful constituents of nematic liquid crystal materials.
Description
~L3~7~0 LATERALLY FLUORINATED 4-CYANOPHENYL AND 4'-CYANOBIPH_NYL BEN~OATES
This invention relates to laterally fluorinated 4-cyanophenyl and 4'-cyanobiphenyl benzoates and to liquid crystal mixtures and devices using them.
Liquid crystal materials are well known for use in electro-optical display devices such as calculators, watches and the like. A commonly used type of li~uid crystal material is that which shows a nematlc liquid crystalline phase. Desirable `
eharacteristics ln a nematic liquid crystal material include a high nematic to isotropic (N I) transition temperature, a low solid crystal to nematic (K - I) transition temperature, and the absence of smectic (S) phases. Other desirable characteristics include low viscosity, ease of manufacture, chemical and thermal stability.
Nematic liquid crystal materials generally consist of a mixture o~ ahemical compounds. One class of such compounds are 4-cyanophenyl and 4'-cyanobiphenyl esters of structure, R (( ~) ~ C0~ CN
~0 R~ COO (~\~~CN
where R may be alkyl, alkoxy, acyloxy or alkylcarbonato disclosed respectively in U.S. Patent Nos. g,138,359 and 3,951,846. Some halogenated analogues of these compounds have been investigated, D
.~ ,.
, . ~ . . , ~,, , j , ~ . ~
~ "" " ,, . .," ` ; '` '` ~ , ' :~, ~ ' ;" ' ;' '' ;;
~3~7~
- la - ~2762-542 for example fluorlnated co~pounds such as-R ~ > C00 ~ -CN
are described in Mol Cryst Liq Cryst 109(2-4), (1984), pl68-78 and in Japanese Unexamined Paten~ Publication Nos. 58/210982 ~published in 1983), 60/69190 (published in 1985), 63/122669 (published in 1988), 61/3056S (published in 1986) and 61/50953 (published in 1986) and U.S. Patent No. 4,551,280.
Japanese Unexamined Patent Publication No. 61/106550 (published in 1986) describes compounds o~ structure, R 0 ~ COO--<O~CN
Japanese Unexamined Patent Publication No. 61/63645 ~published in 1986) describes the compound, F F
C00- ~ -CN
~3~27~
To date, the axtent to which fluorina~ed compounds for use as liquid crystal compounds could be investigated has been hampered by the unavailability of suitable starting materials, and the difficulties of oryanofluorine chemistry.
The present inventors have investigated the field of fluorinated 4 - cyanophenyl and 4' - cyanobiphenyl esters and have identified a range of novel compounds which are useful components of liquid crystal materials. In the course of this a number of novel and potentially useful fluorinated intermediates have also been prepared.
According to the present invention, novel compounds are provided, having a formula I:
~ [~) ]~ Formu~ I
1 R10 or RlC00~ where R is C1-12 0 or 1 provided that (n + m) i5 0 or 1, each of a, b, c and d are independently 0 or l~provided ~a ~ b + c + d~ is not zero, but excludinq the case where a and b are 0 and m is 0 and one of c or d i9 O.
Compounds of formula I are useEul as constituents of liquid crystal compositions, pa~tioul~rly nematic liquid crystal materials.
The structural preferences expressed below are based _n-ter alia ~n relativa usefulness in nematia liquid crystal ma-terials.
Preferably R contains 3 to 8 carbon atoms, espeaially 3, ~ or 5, and R is n-alkyl or an asymmetrically substikuted alkyl group such as 2-methylbutyl whiah may be in an optically ackivq or racemic form. It is particularly pre~erred that R is n-alkyl or n-alkoxy.
Some preferred overall structures for compounds of formula I
are listed in table 1 below.
Of the structural types listed in table 1, those where R is n-alkyl or n-alkoxy and which contain three phenyl rings generally have higher K-N and N-I transitions than their two-ringed counter-parts, whereas the latter often show nematic phases which supercool ~ ' j ~3327~ "
Tabl~ 1 F F
R ~ -COO- ~ -CN 1.1 1.~ R ~ -COO ~ ~ -CN
F F F
R- ~ -COO ~ -CN 1.2 1.9 R ~ -COO ~ ~ -CN
F F F F
R ~ -COO ~ -CN 1.3 1.10 R ~ -COO ~ ~ -CN
F F F F
-COO- ~ -CN 1.4 1.11 R ~ -COO ~ ~ -CN
F F F F
R- ~ -COO ~ -CN 1.5 1.1~ ~ ~ -COO ~ ~ -CN
F F
F F F
R ~ -COO- ~ -CN 1.6 1.13 R ~ -COO ~ ~ -CN .
F F
F F F F
R ~ -COO ~ -CN 1.7 1.14 R ~ -COO ~ ~ ~CN
F F F
1,15 R ~ -COO ~ ~ C
F F
: ` i, , I , , 4 ~3327~
to well below room tempera-ture. Bo-th of ~hese characteristics are of value in liquid crystal compositions.
Compounds of formula I, including those listed in table 1 may be prepared by a number of routes. Being phenylbenzoate es-ters they may for example be prepared from a phenol and benzoic acid carrying fluorine and other substituents R and CN in appropriate ,~
positions. Esterification may be via ~he dicyclohexylcarbodiimide (DCC) mediated method, the reaction and purification conditions of which are well known to those skilled in the art.
lo Some fluoro-substituted phenols and benzoic acids are commercially a~ailable, such as 3-fluoro-4-cyanophenol, but others may be prepared by tic routes.
Suitable fluoro-substituted phenols may be prepared by schemes A
and D shown in Figs 1 and 2, and suitable fluoro-substituted ben~oic acids may be prepared by schemes B and C shown in Figs 3 and 4. The steps of these routes are summarised below:
Scheme A
HO ~~~ ~ -CN and HO- ~ ~ -CN
lA (i) Mg~ '~; ~ii) (iPrO)3B, THF; (iii) 10~ HCl. .
2A NBS, CH2C12.
3A Br2, HOAc.
4A (i) NaNO2, H2S04; (ii) CUS4'5~12' ~CN~
~12-SA Pd(PPh3)4, k~nzen~, ~M-Na2CO
;6~ B~3~1C~l2cl2~ i Scheme D
F
HO ~ -CN
F .:
lD (i) n8uLi, THF; (ii) CO2(s~, Et20.
2D Oxalyl chloride, DMF, benzene.
~';`
~3~7~
3D 35% ammonia.
4D Thionyl chloride, DMF.
5D AlC13, NaCl.
Scheme B
R- ~ -COOH
1~ (i) Mg, TE~; (ii) CH3(~12)3CHO, Et20-P205, pentane.
3B 5~ Pd/C, pentane, H2 1~ (i) nBuLi, TE~; (ii) 2(s)' Et20-5~ (i) nBuLi, T~; (ii) ( PrO)3B, THF; (iii) 10% HCl.
6~ C4H9Br' K2C3' acetone-Sohemc C
~F) R ~ -COOH
lCI, (i),Pent-1-yne, nBuLi, 1~ ii) ZnCl2, '~;
(iii) compound 3, Pd(PPh3)4, THF.
2C 5% Pd/C, EtOH, H2.
3C Conc. H2S04, water, ~Ac.
4C C4Hg~r~ K2CO3, acetone.
5C ~i) C4HgBr, EtOH, water, NaOH; (ii) 36% HCl.
~3327~
Known acids which may be used in the esterification reaction include non-fluorinated 4 - alkyl and 4 - alkoxy benzoic acids, and 4 - alkyl and 4 - alkoxy phenyl-4'-benzoic acids. These may be used to prepare structures 1.1, 1.8 and 1.9 listed in table 1, and other compounds of formula I in which a and b are both O, and n is 0 or 1.
Certain of the phenols and acids produced in schemes A, B, C
and D ~bove, and certain of the intermediates formed in these routes are novel and constitute a further aspect of this invention.
Compounds of formula I are suitable components of liquid crystal materials, particularly nematic liquid crystal materials.
According to a further aspect of the invention -there is therefore provided a liquid crystal material, being a mixture of at least two compounds, at least one of which is a compound of formula I.
The material may contain two or more compounds of formula I, for example differing only in their substituent R, eg two different n-alkyl and/or n-alkoxy groups. Preferably the materials according to this aspect of the invention contains one or more compounds having a high dielectricanisotropy, and selected from table 2 bclow:
Table 2.
34 R2 ~ ~ -CN 2,1 R2 ~ ~ -CN 2,2 R ~ CH2CH2 ~ -CN 2,3 :~.
{ N ~ 2.4 ~ .
~ ~ 2-5 ` `` 7 ~3327~
Table ~
R2 ~ -C00 ~ -CN 2.6 R2 ~ -C00 ~ -CN 2.7 ~ ~ ~ 2.~
where R i5 alkyl or alkoxy containing 3 to 10 carbon atoms.
It is especially preferred that the material contains one or more compounds of formula 2.1, optionally together with one or more compounds of formula 2.8.
The liquid crystal material of this aspect of the invention may also contain compounds of low dielectric anisotropy, for example one or more compounds as listed below in taDle 3 T~ble 3 R3- ~ -C00 ~ -R4 3-]
X
R3 ~ -C00 ~ -R4 3,2 R 3-~-coo~ -R4 3,3 ~, R3- ~ R4 3~4 R3 ~ ~ -R4 3~5 3D ~ O 3.6 R3 ~ -CH2CH2 ~ -R4 3 7 F
R3-0-CH2CH2~_~_R43, ~S
Where R3 and R are independently C3 to C10 alkyl or alkoxy and X is fluorine or hydrogen.
~27~
Typically but not exclusively a liquid crystal material of this aspect of the invention will contain:
high dielectric anisotropy compound~3) ¦
eg as listed in table 2 ~5-95 wt %
low dielectric anisotropy compound(s) eg as liste~ in table 3 )o_50 wt %
compound(s) of formula I ~-50 wt %
additives 0-10 wt %
the total being 100 wt %.
Alditives may for example include pleochroic dyes, eg one or more of those described in EP-A-~2300~91.
The liquid crystal material oE this aspect of the invention may be used in any o~ the known types of nematic liquid crystal device, for example: the twisted nematic effect device, which may be multiplexed; the Freedericksz effect devi.ce using materials of positive or negative dielectria anisotropy ; th~ cholesteric mem~ry mode device; the cholesteric to nematic phase ch~nge effect device ~ti~ese latter two devices require a materi~l which contains one or more optically active compounds, for example a compound of formula I, or a compound as listed in table 2 or ~ in which R, R2, R3 or ~4 is a group containing an asymmetrically sub-stituted carbon atom, in particular (-~) or (-) 2-methylbutyl or 2-methylbutyloxy~, the dynamic scattering effect device or khe two frequenoy switchin~ efrect devioe. A liquid crystal electro-~5 optic di~play device ~hich uses a li~uld crystal material that i9 a mixture Or at least t~o compounds, on~ of wh~oh i~ a oompounl of formula I is a furthar a~pect of this invention. The method of Qonstruotion and,operation o~ such devices i9 well known in qhe art.
~ The invention will now be described by way of example only with reference to~
Figs 1, 2, ~ and 4 showing preparative roj~es to fluorinated :
phenols and ben~oic acids.
Figs 5 and 6 showing routes to compounds of formula I. :
Eig 7 showing a liquid crystal electro-optic display device.
Example l: Schem~ A
4-Methoxyphenylboronic acid (1). (Step lA) A solution of the Grignard reagent, prepared from 4-~romoanisole(80.0 g, 0.43 mol) and magnesium (11.96 g, 0.~9 mol) in dry THF(300 ml) was added dropwise to a stirred, cooled (-78 C) solution of tri-isopropyl borate (161.7 g, 0.86 mol) in dry T~
(50 ml) under dry nitrogen. The stirred mixture was allowed to warm o to room temperature overnight and was then stirred at room temperature ~or 1h with 10% hydrochloric acid (300 ml). The product was extracted into ether (twice), the combined ethereal extracts were washed with waterand dried (MgSO4). The solvent was removed in vacuo to yield a cream-coloured solid (58.5 g) which was recrystallised from water to give colourless crystals.
Yield 27.7 g, 43~.
mp 201-202 C.
~ote: A cream-coloured oil was separated during the above recryistallisation which solidified on cooling to give a cream-coloured solid.
Yield 17.5 g.
i ~0 ,~ .. , .. , . ... .... , ~ .
~3~7~
4~Bromo-2-fluoroaniline (2). (Step 2A) N-~3romosuccinimide 1160.4 g, 0.90 mol) was added in small portions to a stirred, cooled solution of 2-fluoroaniline (100.0 g, 0.90 mol) in dry dichloromethane ~400 ml). The stirred mixture was allowed to warm to 0 C over 45 min, washed with water and dried (MsSO4). The solvent was removed in vacuo to yield a red solid (180 g) which was steam distilled to give a colourless solid.
l~ Yield 120.0 g, 70~.
mp 41-92 C.
4-Bromo=2-fluorobenzonitrile (3). (Step 4A) Concentrated sulphuric acid (60 ml) was added dropwise to a stirred mixture of compound 2 (75.0 g, 0.39 mol), water (150 ml) and glacial acetic acid (185 ml). The clear solution was cooled to -5 C (an emulsion formed) and a solution of sodium nitrite (30.0 g, 0.9~ mol) in water (100 ml) was added dropwise; the stirred mixture was maintained at -5C for 15 min.
A solution of potassium cyanide (128.3 g, 1.98 mol) in water (300 ml) was added dropwise to a stirred solution of copper(II) sulphate pentahydrate ~118.1 g, 0.98 mol) in water (300 ml) and ice `
(300 g) a~ 10-20 C. Sodium hydrogen carbonate (265.1 g, 3.16 mol) and ~yclohe~ne (9$0 ml) were added, the temperature was raised to SO C and the cold diazonium salt mixture was added in portions with rapid stirring. The mixture was cooled, the organic layer was separated and the aqueous layer was washed with ether (twice)~ The combined organic phases were washed with water, 10% sodium hydroxide, water and dried (MgSO~). The solvent was removed in vacuo to afiord 133~7~ `
a dark brown solid (78.0 g) which was steam distilled to give an off-white solid.
Yield 59.2 g, 76~.
mp 69-70 C.
4-Cyano-3-fluoro-4'-methoxvbiphenyl (4). (Sk~p 5A) A solution of compound 1 (10.64 g, 0.07 mol) in ethanol (90 ml) was added dropwise to a stirred mixture of compound 3 (12.0 g, 0.06 mol) and tetrakis(triphenylphosphine)palladium(0) (2.10 g, 1.82 mmol) in benzene (125 ml) and 2M-sodium carbonate (100 ml) at room temperature under dry nitrogen. The stirred mixture was heated under reflux (90-95 C) for 2.5 h (i.e., until glc analysis revealed absence of starting material). The mixture was cooled and stirred for 1 h at room temerature with 30~ hydrogen peroxide (2 ml). The mixture was cooled further to 2 C, the product was filtered off and washed with water. The product was dried (CaC12) in vacuo to give a yellow powder.
Yield 11.9 g, 83~.
mp 153-154 &.
4-Cyano-3-~luoro-4'-hydr~ biphenyl (S). (~tep 6A) A 301ution o~ boron tribromide (12.0 ml, 31.a ~, 0.13 mol) in dry dichloromethane (100 ml) was added dropwise to a stirred, cooled (-78 C) solution of compound 4 (14.0 g, 0.06 mol) in dry dichloranethane (250 ml~ under dry nitrogen. The stirred mixture was allowed to warm ~:, 1332~l~o to room temperature over 20 h (i.e., until glc analysis revealed absence of starting material). Water was added and a yellow precipitate was produced. The product was extracted into ether (twice), and the combined ethereal extracts were washed with water and dried (MgSO4). The solvent was removed in vacuo to afford a pale-yellow pcwder.
Yield 13.1 g, 100%.
mp 201-202 &.
4-Bromo-2~6-difluoroaniline (6). (Step 3A) A solution of bromine (127.0 g, 0.79 mol) in glacial acetic acid (200 ml) was added slowly, dropwise to a stirred solution of 2,6-difluoroaniline (101.5 g, 0.79 mol) in glacial acetic acid (550 ml) keeping the temperature below 25 C. The mixture was stirred at room temperature for 2 h, and then sodium thiosulphate(50 g), sodium acetate (125 g) and water (700 ml) were added and the mixture was cooled in a refrigerator overnight. The product was ~iltered off, dissolved in ether, and the ether phase was r~ashed with water, 10~ sodium hydroxide, water and dried (M~SO~). The solvent was ~ removed in vacuo to yield a pale yellow solid (134 g) which was steam dis~ d ~o give a colourless solid. , ~ `
Yield 117.9 g, 72%.
mp 67-68 C.
:
~ .
~.
~f 13 ~3327~
4-8romo-2,6-difluorobenzonitrile (7). (Step 4A) A stirred mixture of compound 6 (56.0 g, 0.27 mol) and concentrated sulphuric acid-water (1:1, 250 ml) was heated until a solution was obtained. The mixture was cooled to -10 & and a solution of sodium nitrite (30.9 g, 0.45 mol) in water (70 ml) was added dropwise. The mixture was stirred at -5 C for 2.5 h.
A solution of potassium cyanide (97.5 g, 1.50 mol) in water was added dropwise to a stirred solution of copper(II) sulphate pentahydrate (86.5 g, 0.35 mol) in water (200 ml) and ice (130 g).
lO Sodium hydrogen carbonate (300 g), cyclohexane (1200 ml) and glacial acetic acid (130 ml) were added, the temperature was raised to 50 &
and the cold diazonium salt mixture was added in portions with rapid stirring. The mixture was cooled, the organic layer was separated and the aqueous layer was washed with ether (twice). The combined organic phases were washed with water, 10~ sodium hydroxide, water and dried (MgSO4), The solvent was removed in vacuo to afford a dark-brown solid (58.5 g) which was steam distilled to give a light-orange solid.
~O Yield 31.7 g, 54~.
mp 79-80 &.
4-C~tano-3~$-di~luoro-4'-methoxtbiphenyl (8). (Step 5A) A solution of compound 1 (11.50 g, 0.076 mol) in ethanol (90 ml) was added dropwise to a stirred mixture of compound 7 (15.0 g, 0.069 mol) and tetrakis(triphenylphosphine)palladium~0) (2.38 gl 2.06 mmol) in benzene (130 ml) and 2M-sodium carbonate ~ ;
(100 ml) at room temperature under dry nitrogen. The stirred mixture 14 1~3~7~0 was heated under reflux (90-95 C) for 4.5 h (i.e., until glc analysis revealed absence of starting material). The mixture was cooled and stirred for 1 h at ro~ temperature with 309s hydrogen peroxide (2 ml). The mixture was further cooled to 2 C, and the 5 product was filtered off and washed with water. The product was dried (CaCl2) in vac o to give fawn-coloured needles.
Yield 14.1 g, 84%.
mp 205-207 C.
lO 4-Cyano-3,5-difluoro-4'-hydroxybiphenyl (9). (Step 6A) A solution of boron tribromide (25.0 ml, 61.5 g, 0.25 mol) in dry dichloromethane (140 ml) was added dropwise to a stirred, cooled (-78 C) solution of compound 8 (12.22 g, 0.05 mol) in dry dichloromethane (250 ml) under dry nitrogen. The stirred mixture was 15 allowed to warm to room temperature over 9 h (i.e., until glc analysis revealed absence of starting material). The mixture was cooled to -10 C, water was added slowly ~exothermic) and coolecl to 2 &.
Ille product was filtered off, washed with water and dried ~CaCl2) in vacuo to give a pale-yellow powder.
~0 Yield 13.3 g, 10096.
mp 230-231 C.
~: ' ~327~ ~
Examp]e ~ Sch~me D
2,6-Difluoro-4-methoxYbenzoic acid (24). (Step lD) A solution of n-butyllithium (10.0 M in hexane; 25.0 ml, 0,25 mol) was added drop~ise to a stirred, cooled (-78 C) solution of 3,5-dilluoroanisole (35.9 g,0.25 ~,ol) in dry THF (200 ml) under dry nitrogen. The stirred mixture was maintained under these conditions for 2.5 h and then poured into a slurry of solid carbon dioxide and dry ether. The product was ex~racted in-to 10~ sodium hydroxide (twice), the combined basic extracts were acidified with 36~
hydrochloric acid, and the product was extracted into e-ther (twice), the combined ethereal extracts were ~ashed with water and dried (MgSO4). The solvent was removed in vacuo to qive a colourless solid.
~ .
15 Yield 46.5 g, 99%.
mp - 184-185 &.
~' .
2,6-Difluoro-4-methXYbenZoyl chloride (~5)- (Step 2D) A solution o~ oxalyl chloride (36.5 gt 0.29 mol) in dry benzene (50 ml) was added dropwise to a stirred solution o~ compound 24 (25,5 g, 0.14 mol) and dry D~F ~40 drops) in dry ben~ene (500 ml) at ro~n temperature. The mixture was stirred at room t~perature overni~ht and th~ excess~o~ dxalyl chloride andIbenzene werelremoved in vacuo.
13327~ `
2,6-Difluoro-4-methoxybenzamide (26).(Step 3D) The crude acid chloride (25) was dissolved in dr~ diglyme (60 ml) and added dropwise at room temperature with gentle stirring to 35~ ammonia (750 ml). The resulting colourless precipitate was filtered off and driecl (CaC12) ln vacuo to give a colourless solid.
Yield 21.2 g, 81%.
mp 158-159 C.
2l6-Difluoro-4-methoxybenzonitrile (27).(step 4D) A solution of thionyl chloride (139.0 g, 1.17 mol) in dry ~YF
(150 ml) was added to a stirred solution of compound 26 (20.0 g, 0.11 mol) in dry DMF (250 ml) at room temperature. me mixture was stirred at room temperature overnight and then poured onto ice-water. The product was extracted into ether (twice), and the combined ethereal extracts were washed with water, saturated sodium hydrogen carhonate, water and dried (MgSO~). The solvent was removed in vacuo to give o~f-white crystals.
Yield 17.7 y, 95~.
mp 59-60 C.
2,6-Pi~ oro~4-hYdroxYbenæonitrile (2~). (St~p 5D) A stirred, homogeneous mixture of finely powdered, compound 27 (17.0 g, 0.10 mol), aluminium chloride (29.4 g, 0.22 mol) and `
sodium chloride (7.1 g, 0.12 mol) was heated to 180 C over 25 min and then at 180 C for 1h (glc and tlc analyses both revealed a complete reaction). Ice-water was added, and the product was extracted into ether (twice). The com~ined ethereal extracts were washed with water, and the product was extracted into 10% sodium hydroxide (twice) and the combined basic extracts were acidified with 36~o hydrochloric acid. The product was extacted into ether (twice), and the combined ethereal extracts were washed with water and dried (MgS04). The solvent was removed ln vacuo to give a fawn solid.
Yield 14.5 g, 946.
mp 119-120 C.
Example ~: Scheme B.
1-~3,5-DifluoroPhenYl)pentan-1-ol (11). (Step lB) A solution of pentanal (19.0 g, 0.22 mol) in dry ether (75 ml) was added dropwise to a stirred solution of the Grignard reagent at roGm temperature, under dry nitrogen, prepared from 1-bromo-3,5-difluorobenzene (50~2 g, 0~26 1) and magnesium (7.25 g, 0.30 mol) in dry THF (100 ml~. The stirred mixture was heated under reflux for 2 h, cooled and a saturated solution of ammonium chloride (300 ml) was added. me product was extracted into ether (twice), and the combined ethereal extracts were washed with water and dried (MgSO~). The solvent was removed ln vacuo to give a pale-orange liquid (51.1 g) which was distilled to yield a colourless liquid. ,S~ller quantities o-E crude prcduct were purified by column chromatography (silca gel/dichloromethane) to yield a colourless liquid (92%).
~5 Yield 35.8 g, 69%.
bp 90 C at 0.5 mm Hg.
~3327~
1~
3,5-Difluoro-1-pent-1'~enylbenzene (12).(Step 2B) Phosphorus(V) oxide (64.5 g, 0.45 mol) was added in portions to a stirred solution of compound 11 (35.0 g, 0O175 mol) in dry pentane (150 ml) at room temperature. The mixture was stirred at room temperature overnight (glc analysis revealed absence of starting material) and filtered.
3,5-Difluoro-l-pentylbenzene (13).~Step 3B) 5% Palladium-on-charcoal (4.0 g) was added to the above filtrate [i.e. compound 12 in pentane (150 ml)] at room temperature.
The stlrred mixture was hydrogenated at atmospheric pressure for g h (i.e., until glc analysis revealed absence of starting material) and the mixture was filtered. The majority of the pentane was removed in vacuo, and the final amount of pentane was distilled off (760 mm Hg) at 38& and the residue was then distilled to yield a colourless liquid.
Yield 23.4 ~, 73%.
bp 200 C at 760 mm Hg.
2,6-Difluoro-4-pentYlbenzoic acid (14)~ (Step L~B) A solution oE n-butyllithium (10.5 M in hexane; 2.70 ml, 0.02~ mol) wa~ added dropwise to a stirred, cooled (-78 C) so~ution oE compound 13 (5.10 g, 0.028 mol) in dry l~ (30 ml) under dry nitrogen. The stirred mixture was maintained under these conditions for 2.5 h and then poured onto a slurry of solid carbon dioxide and dry ether. The product was extracted into 10~ sodium hydroxide which ' ~ ' 13327~
was then acidified with 36~ hydrochloric acid. The acidic mixture ~as washed with ether (twice), and the combined ethereal layers were washed with water and dried (~ O4). The solvent was removed n ~a o to yield a colourless solid.
Yield 5.8 g, 91~.
mp 75-76 &.
2,6-Difluoro-4-pentYl~henYlboronic acid (15). (Step ~B) A solution of n-butyllithium (10.4 M in hexane; 2.70 ml, lO 0.028 mol) was added dropwise to a stirred, cooled (-78 C) solution of ccmpound 13 (5.00 g, 0.027 mol) in dry THF (60 ml) under dry nitrogen. The stirred mixture was maintained under these conditions for 2.5 h and a previously cooled solution of tri-isopropyl borate (10.22 g, 0.054 mol) in dry THF (50 ml) was added dropwise at 15 -7B C. The stirred mixture was allowed to warm to room temperature overnight and stirred for 1 h with 10% hydrochloric acid (30 ml). The product was extracted into ether (twice), and the combined ethereal extracts were washed with water and dried (~IgS04). The solv~nt was removed ln vacuo to give a colourless solid.
, Yield 6.7 g, 100 mp ~ 9s-1oo c~
1-Butoxy-3l5-difluorobenzene (16~.(step 6B) A solution of 1-bromobutane (11.0 g, 0.08 mol) in acetone ~30 ml) was added dropwise to a stirred, refluxing mixture of 3,5-difluorophenol (9.1 g, 0.07 mol) and potassium carbonate ~30 g, ~327~
0.2 mol) in acetone (200 ml). The stirred mixture was heated under reflux for 24 h ~glc analysis revealed absence of starting material).
The product was extracted into ether (twice), and the combined ethereal extracts were washed with water, 5% sodium hydroxide, water and dried (.~gSO4) Most of the solvent was rernoved in vacuo, and after the removal of the final amount of solvent and the excess of 1-bromobutane at atmospheric pressure, the residue was distilled to yield a colourless liquid.
o Yield 11.7 g, 9o%.
bp 204 C at 760 mm Hg.
This invention relates to laterally fluorinated 4-cyanophenyl and 4'-cyanobiphenyl benzoates and to liquid crystal mixtures and devices using them.
Liquid crystal materials are well known for use in electro-optical display devices such as calculators, watches and the like. A commonly used type of li~uid crystal material is that which shows a nematlc liquid crystalline phase. Desirable `
eharacteristics ln a nematic liquid crystal material include a high nematic to isotropic (N I) transition temperature, a low solid crystal to nematic (K - I) transition temperature, and the absence of smectic (S) phases. Other desirable characteristics include low viscosity, ease of manufacture, chemical and thermal stability.
Nematic liquid crystal materials generally consist of a mixture o~ ahemical compounds. One class of such compounds are 4-cyanophenyl and 4'-cyanobiphenyl esters of structure, R (( ~) ~ C0~ CN
~0 R~ COO (~\~~CN
where R may be alkyl, alkoxy, acyloxy or alkylcarbonato disclosed respectively in U.S. Patent Nos. g,138,359 and 3,951,846. Some halogenated analogues of these compounds have been investigated, D
.~ ,.
, . ~ . . , ~,, , j , ~ . ~
~ "" " ,, . .," ` ; '` '` ~ , ' :~, ~ ' ;" ' ;' '' ;;
~3~7~
- la - ~2762-542 for example fluorlnated co~pounds such as-R ~ > C00 ~ -CN
are described in Mol Cryst Liq Cryst 109(2-4), (1984), pl68-78 and in Japanese Unexamined Paten~ Publication Nos. 58/210982 ~published in 1983), 60/69190 (published in 1985), 63/122669 (published in 1988), 61/3056S (published in 1986) and 61/50953 (published in 1986) and U.S. Patent No. 4,551,280.
Japanese Unexamined Patent Publication No. 61/106550 (published in 1986) describes compounds o~ structure, R 0 ~ COO--<O~CN
Japanese Unexamined Patent Publication No. 61/63645 ~published in 1986) describes the compound, F F
C00- ~ -CN
~3~27~
To date, the axtent to which fluorina~ed compounds for use as liquid crystal compounds could be investigated has been hampered by the unavailability of suitable starting materials, and the difficulties of oryanofluorine chemistry.
The present inventors have investigated the field of fluorinated 4 - cyanophenyl and 4' - cyanobiphenyl esters and have identified a range of novel compounds which are useful components of liquid crystal materials. In the course of this a number of novel and potentially useful fluorinated intermediates have also been prepared.
According to the present invention, novel compounds are provided, having a formula I:
~ [~) ]~ Formu~ I
1 R10 or RlC00~ where R is C1-12 0 or 1 provided that (n + m) i5 0 or 1, each of a, b, c and d are independently 0 or l~provided ~a ~ b + c + d~ is not zero, but excludinq the case where a and b are 0 and m is 0 and one of c or d i9 O.
Compounds of formula I are useEul as constituents of liquid crystal compositions, pa~tioul~rly nematic liquid crystal materials.
The structural preferences expressed below are based _n-ter alia ~n relativa usefulness in nematia liquid crystal ma-terials.
Preferably R contains 3 to 8 carbon atoms, espeaially 3, ~ or 5, and R is n-alkyl or an asymmetrically substikuted alkyl group such as 2-methylbutyl whiah may be in an optically ackivq or racemic form. It is particularly pre~erred that R is n-alkyl or n-alkoxy.
Some preferred overall structures for compounds of formula I
are listed in table 1 below.
Of the structural types listed in table 1, those where R is n-alkyl or n-alkoxy and which contain three phenyl rings generally have higher K-N and N-I transitions than their two-ringed counter-parts, whereas the latter often show nematic phases which supercool ~ ' j ~3327~ "
Tabl~ 1 F F
R ~ -COO- ~ -CN 1.1 1.~ R ~ -COO ~ ~ -CN
F F F
R- ~ -COO ~ -CN 1.2 1.9 R ~ -COO ~ ~ -CN
F F F F
R ~ -COO ~ -CN 1.3 1.10 R ~ -COO ~ ~ -CN
F F F F
-COO- ~ -CN 1.4 1.11 R ~ -COO ~ ~ -CN
F F F F
R- ~ -COO ~ -CN 1.5 1.1~ ~ ~ -COO ~ ~ -CN
F F
F F F
R ~ -COO- ~ -CN 1.6 1.13 R ~ -COO ~ ~ -CN .
F F
F F F F
R ~ -COO ~ -CN 1.7 1.14 R ~ -COO ~ ~ ~CN
F F F
1,15 R ~ -COO ~ ~ C
F F
: ` i, , I , , 4 ~3327~
to well below room tempera-ture. Bo-th of ~hese characteristics are of value in liquid crystal compositions.
Compounds of formula I, including those listed in table 1 may be prepared by a number of routes. Being phenylbenzoate es-ters they may for example be prepared from a phenol and benzoic acid carrying fluorine and other substituents R and CN in appropriate ,~
positions. Esterification may be via ~he dicyclohexylcarbodiimide (DCC) mediated method, the reaction and purification conditions of which are well known to those skilled in the art.
lo Some fluoro-substituted phenols and benzoic acids are commercially a~ailable, such as 3-fluoro-4-cyanophenol, but others may be prepared by tic routes.
Suitable fluoro-substituted phenols may be prepared by schemes A
and D shown in Figs 1 and 2, and suitable fluoro-substituted ben~oic acids may be prepared by schemes B and C shown in Figs 3 and 4. The steps of these routes are summarised below:
Scheme A
HO ~~~ ~ -CN and HO- ~ ~ -CN
lA (i) Mg~ '~; ~ii) (iPrO)3B, THF; (iii) 10~ HCl. .
2A NBS, CH2C12.
3A Br2, HOAc.
4A (i) NaNO2, H2S04; (ii) CUS4'5~12' ~CN~
~12-SA Pd(PPh3)4, k~nzen~, ~M-Na2CO
;6~ B~3~1C~l2cl2~ i Scheme D
F
HO ~ -CN
F .:
lD (i) n8uLi, THF; (ii) CO2(s~, Et20.
2D Oxalyl chloride, DMF, benzene.
~';`
~3~7~
3D 35% ammonia.
4D Thionyl chloride, DMF.
5D AlC13, NaCl.
Scheme B
R- ~ -COOH
1~ (i) Mg, TE~; (ii) CH3(~12)3CHO, Et20-P205, pentane.
3B 5~ Pd/C, pentane, H2 1~ (i) nBuLi, TE~; (ii) 2(s)' Et20-5~ (i) nBuLi, T~; (ii) ( PrO)3B, THF; (iii) 10% HCl.
6~ C4H9Br' K2C3' acetone-Sohemc C
~F) R ~ -COOH
lCI, (i),Pent-1-yne, nBuLi, 1~ ii) ZnCl2, '~;
(iii) compound 3, Pd(PPh3)4, THF.
2C 5% Pd/C, EtOH, H2.
3C Conc. H2S04, water, ~Ac.
4C C4Hg~r~ K2CO3, acetone.
5C ~i) C4HgBr, EtOH, water, NaOH; (ii) 36% HCl.
~3327~
Known acids which may be used in the esterification reaction include non-fluorinated 4 - alkyl and 4 - alkoxy benzoic acids, and 4 - alkyl and 4 - alkoxy phenyl-4'-benzoic acids. These may be used to prepare structures 1.1, 1.8 and 1.9 listed in table 1, and other compounds of formula I in which a and b are both O, and n is 0 or 1.
Certain of the phenols and acids produced in schemes A, B, C
and D ~bove, and certain of the intermediates formed in these routes are novel and constitute a further aspect of this invention.
Compounds of formula I are suitable components of liquid crystal materials, particularly nematic liquid crystal materials.
According to a further aspect of the invention -there is therefore provided a liquid crystal material, being a mixture of at least two compounds, at least one of which is a compound of formula I.
The material may contain two or more compounds of formula I, for example differing only in their substituent R, eg two different n-alkyl and/or n-alkoxy groups. Preferably the materials according to this aspect of the invention contains one or more compounds having a high dielectricanisotropy, and selected from table 2 bclow:
Table 2.
34 R2 ~ ~ -CN 2,1 R2 ~ ~ -CN 2,2 R ~ CH2CH2 ~ -CN 2,3 :~.
{ N ~ 2.4 ~ .
~ ~ 2-5 ` `` 7 ~3327~
Table ~
R2 ~ -C00 ~ -CN 2.6 R2 ~ -C00 ~ -CN 2.7 ~ ~ ~ 2.~
where R i5 alkyl or alkoxy containing 3 to 10 carbon atoms.
It is especially preferred that the material contains one or more compounds of formula 2.1, optionally together with one or more compounds of formula 2.8.
The liquid crystal material of this aspect of the invention may also contain compounds of low dielectric anisotropy, for example one or more compounds as listed below in taDle 3 T~ble 3 R3- ~ -C00 ~ -R4 3-]
X
R3 ~ -C00 ~ -R4 3,2 R 3-~-coo~ -R4 3,3 ~, R3- ~ R4 3~4 R3 ~ ~ -R4 3~5 3D ~ O 3.6 R3 ~ -CH2CH2 ~ -R4 3 7 F
R3-0-CH2CH2~_~_R43, ~S
Where R3 and R are independently C3 to C10 alkyl or alkoxy and X is fluorine or hydrogen.
~27~
Typically but not exclusively a liquid crystal material of this aspect of the invention will contain:
high dielectric anisotropy compound~3) ¦
eg as listed in table 2 ~5-95 wt %
low dielectric anisotropy compound(s) eg as liste~ in table 3 )o_50 wt %
compound(s) of formula I ~-50 wt %
additives 0-10 wt %
the total being 100 wt %.
Alditives may for example include pleochroic dyes, eg one or more of those described in EP-A-~2300~91.
The liquid crystal material oE this aspect of the invention may be used in any o~ the known types of nematic liquid crystal device, for example: the twisted nematic effect device, which may be multiplexed; the Freedericksz effect devi.ce using materials of positive or negative dielectria anisotropy ; th~ cholesteric mem~ry mode device; the cholesteric to nematic phase ch~nge effect device ~ti~ese latter two devices require a materi~l which contains one or more optically active compounds, for example a compound of formula I, or a compound as listed in table 2 or ~ in which R, R2, R3 or ~4 is a group containing an asymmetrically sub-stituted carbon atom, in particular (-~) or (-) 2-methylbutyl or 2-methylbutyloxy~, the dynamic scattering effect device or khe two frequenoy switchin~ efrect devioe. A liquid crystal electro-~5 optic di~play device ~hich uses a li~uld crystal material that i9 a mixture Or at least t~o compounds, on~ of wh~oh i~ a oompounl of formula I is a furthar a~pect of this invention. The method of Qonstruotion and,operation o~ such devices i9 well known in qhe art.
~ The invention will now be described by way of example only with reference to~
Figs 1, 2, ~ and 4 showing preparative roj~es to fluorinated :
phenols and ben~oic acids.
Figs 5 and 6 showing routes to compounds of formula I. :
Eig 7 showing a liquid crystal electro-optic display device.
Example l: Schem~ A
4-Methoxyphenylboronic acid (1). (Step lA) A solution of the Grignard reagent, prepared from 4-~romoanisole(80.0 g, 0.43 mol) and magnesium (11.96 g, 0.~9 mol) in dry THF(300 ml) was added dropwise to a stirred, cooled (-78 C) solution of tri-isopropyl borate (161.7 g, 0.86 mol) in dry T~
(50 ml) under dry nitrogen. The stirred mixture was allowed to warm o to room temperature overnight and was then stirred at room temperature ~or 1h with 10% hydrochloric acid (300 ml). The product was extracted into ether (twice), the combined ethereal extracts were washed with waterand dried (MgSO4). The solvent was removed in vacuo to yield a cream-coloured solid (58.5 g) which was recrystallised from water to give colourless crystals.
Yield 27.7 g, 43~.
mp 201-202 C.
~ote: A cream-coloured oil was separated during the above recryistallisation which solidified on cooling to give a cream-coloured solid.
Yield 17.5 g.
i ~0 ,~ .. , .. , . ... .... , ~ .
~3~7~
4~Bromo-2-fluoroaniline (2). (Step 2A) N-~3romosuccinimide 1160.4 g, 0.90 mol) was added in small portions to a stirred, cooled solution of 2-fluoroaniline (100.0 g, 0.90 mol) in dry dichloromethane ~400 ml). The stirred mixture was allowed to warm to 0 C over 45 min, washed with water and dried (MsSO4). The solvent was removed in vacuo to yield a red solid (180 g) which was steam distilled to give a colourless solid.
l~ Yield 120.0 g, 70~.
mp 41-92 C.
4-Bromo=2-fluorobenzonitrile (3). (Step 4A) Concentrated sulphuric acid (60 ml) was added dropwise to a stirred mixture of compound 2 (75.0 g, 0.39 mol), water (150 ml) and glacial acetic acid (185 ml). The clear solution was cooled to -5 C (an emulsion formed) and a solution of sodium nitrite (30.0 g, 0.9~ mol) in water (100 ml) was added dropwise; the stirred mixture was maintained at -5C for 15 min.
A solution of potassium cyanide (128.3 g, 1.98 mol) in water (300 ml) was added dropwise to a stirred solution of copper(II) sulphate pentahydrate ~118.1 g, 0.98 mol) in water (300 ml) and ice `
(300 g) a~ 10-20 C. Sodium hydrogen carbonate (265.1 g, 3.16 mol) and ~yclohe~ne (9$0 ml) were added, the temperature was raised to SO C and the cold diazonium salt mixture was added in portions with rapid stirring. The mixture was cooled, the organic layer was separated and the aqueous layer was washed with ether (twice)~ The combined organic phases were washed with water, 10% sodium hydroxide, water and dried (MgSO~). The solvent was removed in vacuo to afiord 133~7~ `
a dark brown solid (78.0 g) which was steam distilled to give an off-white solid.
Yield 59.2 g, 76~.
mp 69-70 C.
4-Cyano-3-fluoro-4'-methoxvbiphenyl (4). (Sk~p 5A) A solution of compound 1 (10.64 g, 0.07 mol) in ethanol (90 ml) was added dropwise to a stirred mixture of compound 3 (12.0 g, 0.06 mol) and tetrakis(triphenylphosphine)palladium(0) (2.10 g, 1.82 mmol) in benzene (125 ml) and 2M-sodium carbonate (100 ml) at room temperature under dry nitrogen. The stirred mixture was heated under reflux (90-95 C) for 2.5 h (i.e., until glc analysis revealed absence of starting material). The mixture was cooled and stirred for 1 h at room temerature with 30~ hydrogen peroxide (2 ml). The mixture was cooled further to 2 C, the product was filtered off and washed with water. The product was dried (CaC12) in vacuo to give a yellow powder.
Yield 11.9 g, 83~.
mp 153-154 &.
4-Cyano-3-~luoro-4'-hydr~ biphenyl (S). (~tep 6A) A 301ution o~ boron tribromide (12.0 ml, 31.a ~, 0.13 mol) in dry dichloromethane (100 ml) was added dropwise to a stirred, cooled (-78 C) solution of compound 4 (14.0 g, 0.06 mol) in dry dichloranethane (250 ml~ under dry nitrogen. The stirred mixture was allowed to warm ~:, 1332~l~o to room temperature over 20 h (i.e., until glc analysis revealed absence of starting material). Water was added and a yellow precipitate was produced. The product was extracted into ether (twice), and the combined ethereal extracts were washed with water and dried (MgSO4). The solvent was removed in vacuo to afford a pale-yellow pcwder.
Yield 13.1 g, 100%.
mp 201-202 &.
4-Bromo-2~6-difluoroaniline (6). (Step 3A) A solution of bromine (127.0 g, 0.79 mol) in glacial acetic acid (200 ml) was added slowly, dropwise to a stirred solution of 2,6-difluoroaniline (101.5 g, 0.79 mol) in glacial acetic acid (550 ml) keeping the temperature below 25 C. The mixture was stirred at room temperature for 2 h, and then sodium thiosulphate(50 g), sodium acetate (125 g) and water (700 ml) were added and the mixture was cooled in a refrigerator overnight. The product was ~iltered off, dissolved in ether, and the ether phase was r~ashed with water, 10~ sodium hydroxide, water and dried (M~SO~). The solvent was ~ removed in vacuo to yield a pale yellow solid (134 g) which was steam dis~ d ~o give a colourless solid. , ~ `
Yield 117.9 g, 72%.
mp 67-68 C.
:
~ .
~.
~f 13 ~3327~
4-8romo-2,6-difluorobenzonitrile (7). (Step 4A) A stirred mixture of compound 6 (56.0 g, 0.27 mol) and concentrated sulphuric acid-water (1:1, 250 ml) was heated until a solution was obtained. The mixture was cooled to -10 & and a solution of sodium nitrite (30.9 g, 0.45 mol) in water (70 ml) was added dropwise. The mixture was stirred at -5 C for 2.5 h.
A solution of potassium cyanide (97.5 g, 1.50 mol) in water was added dropwise to a stirred solution of copper(II) sulphate pentahydrate (86.5 g, 0.35 mol) in water (200 ml) and ice (130 g).
lO Sodium hydrogen carbonate (300 g), cyclohexane (1200 ml) and glacial acetic acid (130 ml) were added, the temperature was raised to 50 &
and the cold diazonium salt mixture was added in portions with rapid stirring. The mixture was cooled, the organic layer was separated and the aqueous layer was washed with ether (twice). The combined organic phases were washed with water, 10~ sodium hydroxide, water and dried (MgSO4), The solvent was removed in vacuo to afford a dark-brown solid (58.5 g) which was steam distilled to give a light-orange solid.
~O Yield 31.7 g, 54~.
mp 79-80 &.
4-C~tano-3~$-di~luoro-4'-methoxtbiphenyl (8). (Step 5A) A solution of compound 1 (11.50 g, 0.076 mol) in ethanol (90 ml) was added dropwise to a stirred mixture of compound 7 (15.0 g, 0.069 mol) and tetrakis(triphenylphosphine)palladium~0) (2.38 gl 2.06 mmol) in benzene (130 ml) and 2M-sodium carbonate ~ ;
(100 ml) at room temperature under dry nitrogen. The stirred mixture 14 1~3~7~0 was heated under reflux (90-95 C) for 4.5 h (i.e., until glc analysis revealed absence of starting material). The mixture was cooled and stirred for 1 h at ro~ temperature with 309s hydrogen peroxide (2 ml). The mixture was further cooled to 2 C, and the 5 product was filtered off and washed with water. The product was dried (CaCl2) in vac o to give fawn-coloured needles.
Yield 14.1 g, 84%.
mp 205-207 C.
lO 4-Cyano-3,5-difluoro-4'-hydroxybiphenyl (9). (Step 6A) A solution of boron tribromide (25.0 ml, 61.5 g, 0.25 mol) in dry dichloromethane (140 ml) was added dropwise to a stirred, cooled (-78 C) solution of compound 8 (12.22 g, 0.05 mol) in dry dichloromethane (250 ml) under dry nitrogen. The stirred mixture was 15 allowed to warm to room temperature over 9 h (i.e., until glc analysis revealed absence of starting material). The mixture was cooled to -10 C, water was added slowly ~exothermic) and coolecl to 2 &.
Ille product was filtered off, washed with water and dried ~CaCl2) in vacuo to give a pale-yellow powder.
~0 Yield 13.3 g, 10096.
mp 230-231 C.
~: ' ~327~ ~
Examp]e ~ Sch~me D
2,6-Difluoro-4-methoxYbenzoic acid (24). (Step lD) A solution of n-butyllithium (10.0 M in hexane; 25.0 ml, 0,25 mol) was added drop~ise to a stirred, cooled (-78 C) solution of 3,5-dilluoroanisole (35.9 g,0.25 ~,ol) in dry THF (200 ml) under dry nitrogen. The stirred mixture was maintained under these conditions for 2.5 h and then poured into a slurry of solid carbon dioxide and dry ether. The product was ex~racted in-to 10~ sodium hydroxide (twice), the combined basic extracts were acidified with 36~
hydrochloric acid, and the product was extracted into e-ther (twice), the combined ethereal extracts were ~ashed with water and dried (MgSO4). The solvent was removed in vacuo to qive a colourless solid.
~ .
15 Yield 46.5 g, 99%.
mp - 184-185 &.
~' .
2,6-Difluoro-4-methXYbenZoyl chloride (~5)- (Step 2D) A solution o~ oxalyl chloride (36.5 gt 0.29 mol) in dry benzene (50 ml) was added dropwise to a stirred solution o~ compound 24 (25,5 g, 0.14 mol) and dry D~F ~40 drops) in dry ben~ene (500 ml) at ro~n temperature. The mixture was stirred at room t~perature overni~ht and th~ excess~o~ dxalyl chloride andIbenzene werelremoved in vacuo.
13327~ `
2,6-Difluoro-4-methoxybenzamide (26).(Step 3D) The crude acid chloride (25) was dissolved in dr~ diglyme (60 ml) and added dropwise at room temperature with gentle stirring to 35~ ammonia (750 ml). The resulting colourless precipitate was filtered off and driecl (CaC12) ln vacuo to give a colourless solid.
Yield 21.2 g, 81%.
mp 158-159 C.
2l6-Difluoro-4-methoxybenzonitrile (27).(step 4D) A solution of thionyl chloride (139.0 g, 1.17 mol) in dry ~YF
(150 ml) was added to a stirred solution of compound 26 (20.0 g, 0.11 mol) in dry DMF (250 ml) at room temperature. me mixture was stirred at room temperature overnight and then poured onto ice-water. The product was extracted into ether (twice), and the combined ethereal extracts were washed with water, saturated sodium hydrogen carhonate, water and dried (MgSO~). The solvent was removed in vacuo to give o~f-white crystals.
Yield 17.7 y, 95~.
mp 59-60 C.
2,6-Pi~ oro~4-hYdroxYbenæonitrile (2~). (St~p 5D) A stirred, homogeneous mixture of finely powdered, compound 27 (17.0 g, 0.10 mol), aluminium chloride (29.4 g, 0.22 mol) and `
sodium chloride (7.1 g, 0.12 mol) was heated to 180 C over 25 min and then at 180 C for 1h (glc and tlc analyses both revealed a complete reaction). Ice-water was added, and the product was extracted into ether (twice). The com~ined ethereal extracts were washed with water, and the product was extracted into 10% sodium hydroxide (twice) and the combined basic extracts were acidified with 36~o hydrochloric acid. The product was extacted into ether (twice), and the combined ethereal extracts were washed with water and dried (MgS04). The solvent was removed ln vacuo to give a fawn solid.
Yield 14.5 g, 946.
mp 119-120 C.
Example ~: Scheme B.
1-~3,5-DifluoroPhenYl)pentan-1-ol (11). (Step lB) A solution of pentanal (19.0 g, 0.22 mol) in dry ether (75 ml) was added dropwise to a stirred solution of the Grignard reagent at roGm temperature, under dry nitrogen, prepared from 1-bromo-3,5-difluorobenzene (50~2 g, 0~26 1) and magnesium (7.25 g, 0.30 mol) in dry THF (100 ml~. The stirred mixture was heated under reflux for 2 h, cooled and a saturated solution of ammonium chloride (300 ml) was added. me product was extracted into ether (twice), and the combined ethereal extracts were washed with water and dried (MgSO~). The solvent was removed ln vacuo to give a pale-orange liquid (51.1 g) which was distilled to yield a colourless liquid. ,S~ller quantities o-E crude prcduct were purified by column chromatography (silca gel/dichloromethane) to yield a colourless liquid (92%).
~5 Yield 35.8 g, 69%.
bp 90 C at 0.5 mm Hg.
~3327~
1~
3,5-Difluoro-1-pent-1'~enylbenzene (12).(Step 2B) Phosphorus(V) oxide (64.5 g, 0.45 mol) was added in portions to a stirred solution of compound 11 (35.0 g, 0O175 mol) in dry pentane (150 ml) at room temperature. The mixture was stirred at room temperature overnight (glc analysis revealed absence of starting material) and filtered.
3,5-Difluoro-l-pentylbenzene (13).~Step 3B) 5% Palladium-on-charcoal (4.0 g) was added to the above filtrate [i.e. compound 12 in pentane (150 ml)] at room temperature.
The stlrred mixture was hydrogenated at atmospheric pressure for g h (i.e., until glc analysis revealed absence of starting material) and the mixture was filtered. The majority of the pentane was removed in vacuo, and the final amount of pentane was distilled off (760 mm Hg) at 38& and the residue was then distilled to yield a colourless liquid.
Yield 23.4 ~, 73%.
bp 200 C at 760 mm Hg.
2,6-Difluoro-4-pentYlbenzoic acid (14)~ (Step L~B) A solution oE n-butyllithium (10.5 M in hexane; 2.70 ml, 0.02~ mol) wa~ added dropwise to a stirred, cooled (-78 C) so~ution oE compound 13 (5.10 g, 0.028 mol) in dry l~ (30 ml) under dry nitrogen. The stirred mixture was maintained under these conditions for 2.5 h and then poured onto a slurry of solid carbon dioxide and dry ether. The product was extracted into 10~ sodium hydroxide which ' ~ ' 13327~
was then acidified with 36~ hydrochloric acid. The acidic mixture ~as washed with ether (twice), and the combined ethereal layers were washed with water and dried (~ O4). The solvent was removed n ~a o to yield a colourless solid.
Yield 5.8 g, 91~.
mp 75-76 &.
2,6-Difluoro-4-pentYl~henYlboronic acid (15). (Step ~B) A solution of n-butyllithium (10.4 M in hexane; 2.70 ml, lO 0.028 mol) was added dropwise to a stirred, cooled (-78 C) solution of ccmpound 13 (5.00 g, 0.027 mol) in dry THF (60 ml) under dry nitrogen. The stirred mixture was maintained under these conditions for 2.5 h and a previously cooled solution of tri-isopropyl borate (10.22 g, 0.054 mol) in dry THF (50 ml) was added dropwise at 15 -7B C. The stirred mixture was allowed to warm to room temperature overnight and stirred for 1 h with 10% hydrochloric acid (30 ml). The product was extracted into ether (twice), and the combined ethereal extracts were washed with water and dried (~IgS04). The solv~nt was removed ln vacuo to give a colourless solid.
, Yield 6.7 g, 100 mp ~ 9s-1oo c~
1-Butoxy-3l5-difluorobenzene (16~.(step 6B) A solution of 1-bromobutane (11.0 g, 0.08 mol) in acetone ~30 ml) was added dropwise to a stirred, refluxing mixture of 3,5-difluorophenol (9.1 g, 0.07 mol) and potassium carbonate ~30 g, ~327~
0.2 mol) in acetone (200 ml). The stirred mixture was heated under reflux for 24 h ~glc analysis revealed absence of starting material).
The product was extracted into ether (twice), and the combined ethereal extracts were washed with water, 5% sodium hydroxide, water and dried (.~gSO4) Most of the solvent was rernoved in vacuo, and after the removal of the final amount of solvent and the excess of 1-bromobutane at atmospheric pressure, the residue was distilled to yield a colourless liquid.
o Yield 11.7 g, 9o%.
bp 204 C at 760 mm Hg.
4-sutOxY-2,6-difluorobenzoic acid (17).(st~
P
A solution of n-butyllithium (10.5 M in hexane; 3.60 ml, 0.038 mol) was added dropwise to a stirred, cooled (-78C) solution 15 of com~ound 16 (7.00 g, 0.038 mol) in dry THF (35 ml) under dry nitrogen. The stirred mixture was maintained under these conditions for 2.5 h and then poured onto a slurry of solid carbon dioxide and dry ether~ The product was extracted into 10% sodiuun hydroxide which was then acidified with 36~ hydrochloric acid. The product was 2Q ~iltered off and dried ~CaCl2) in v~cuo to glve a colourless solid.
Yield 8~3 g, 96~.
mp 110-112 C.
~3~2~
Example 4: Scheme C
4-sutoxy-2-fluorobenzonitrile ~18). (Step 4C) A solution of 1-bramobutane (18.0 g, 0.13 mol) in acetone ~30 ml) was added dropwise to a stirred refluxing mixture of 2-fluoro-4-hydroxybenzonitrile (15.0 g, 0.11 mol) and potassium carbonate (46.0 g, 0.33 mol) in acetone (300 ml). The stirred mixture was heated under reflux for 21 h (glc analysis revealed absence of starting material). The product was extracted into ether (twice), and the combined ethereal extracts were washed with water, 5% sodium hydroxide, water and dried (MgSO4). The solvent and the excess of 1- bromobutane were removed _n vacuo to yield a pale-orange solid.
Yield 19-5 g, 93%-mp 25-26 C.
4-Butoxy-2-fluorob--enzo c acid (19)- (Step 3C) A mixture of concentrated sulphuric acid ~190 ml) and water (190 ml) was added dropwise to a stirred solution o~ campound 18 ~19~0 g, 0.098 mol) in glacial acetlc acid (380 ml). ~he stirred mixture was heated under re~lux for 48 h, cooled in a refrigerator ~or 24 h and the product was Eiltered oEf and dxied ~aCl2) in vacuo to givq pale-yellow crystals.
Yield 18.7 g, 90%.
mp 93-95 C.
- 313327~
2-Fluoro-4-pent~ rn-1'-ylbenzonitrile (20)- (Step lC) A solution of n-butyllitium (10.0 M in hexane; 10.0 ml, 0.10 mol) was added dropwise to a stirred, cooled (<0 C) solution of pent-1-yne (6.80 g, 0.10 mol) in dry THF (51 ml) under dry nitrogen. This mixture was stirred for 10 min and then a solution of zinc chloride (13.63 g, 0.10 mol) in dry T~ (100 ml) was added dropwise at <0 C. The mixture was stirred at room temperature for 15 min and a solution of compound 3 (20.0 g, 0.10 mol) in dry THF (100 ml) followed by a solution of tetrakis(triphenylphosphine)palladium(0) (2.31 g, 2.0 mmol) in dry THF (25 ml) were added dropwise at <0 C. The mixture was stirred at room temperature for 20 h (glc analysis revealed absence of starting material; 20 h was probablv longer than required for reaction) and poured into 10~ hydrochloric acid (200 ml). The product was extracted into ether (twice), and the combined ethereal extracts were washed with water, saturated sodium hydrogen carbonate, water and dried (MgSO4). The solvent was removed in v c o to af~ord an orange liquid which was distilled to yield a pale-yellow oil.
~O Yield 17.6 g, 94%.
bp 100-105 C at ~.1 mm Hg.
Note.
* Sodium dried THF was distilled from lithium aluminium hydride and kept over a molecular sieve (type 4A).
Zinc chloride (ACS reagent) was dried overnight at 100 C~
~3327~
2-Fluoro-4-pentylbenzonitrile (21). (Step 2C) A stirred mixture of compound 20 (16.0 g, 0.085 mol~ and 5%
palladium-on-charcoal (4.00 g) in ethanol (100 ml) was hydrogenated at atmospheric pressure for 8 h (glc analysis revealed absence of starting material). The catalyst was filtered off and the solvent was removed in vacuo to yield a pale-orange semi-solid.
Yield 15.35 g, 95%.
mp not recorded, probably around 20 &.
2-Fluoro-4-pentylbenzoic acid (22). (St~p 3C) A mixture of concentrated sulphuric acid (150 ml) and water (150 ml) was added dropwise to a stirred solution of compound 21 (15.0 g, 0.078 mol) in glacial acetic acid (300 ml). The stirred mixture was heated under reflux for 48 h, cooled in a refrigerator overnight and the product was filtered off. The product was dissolved in ether, extracted into 10% sodium hydroxide, which was then acidified with 3Z% hydrochloric acid, washed with ether (twice), and the combined ~thereal phases were washed with water and dried ~MgSO~). The solvent was removed in vacuo to give a brown crystalline solid.
Yield 11.5 g, 70%.
mp 90-91 &.
,~ 13327A~
2l~
4-Butoxy~enzoic acid (23).(Step 5C) 1-Bromobutane (22.6 g, 0.165 mol) was added dropwise at room temperature to a stirred mixture of 4-hydroxybenzoic acid (15.0 g, 0.11 mol) in ethanol (60 ml) and sodium hydroxide (10.60 g) in the minimum amount of water. The stirred mixture was heated under reflux overnight (tlc analysis revealed a complete reaction), and then the ethanol was distilled off and an equal volume o~ water was added.
The mixture was boiled to give a solution, cooled, washed with ether and acidified with 36% hydrochloric acid. The cooled mixture ~s filtered, and the product was ~ashed with water to give a colourless solid (13.9 g) which was recrystallised from ethanol to give colourless crystals.
Yield 12.1 g, 57~.
mp 149-150 C.
Although illustrated in examples l, 2, 3 and 4 abova, and in Fig~ 1, 2, 3 and 4 for -the preparation o~ the n-pentyl and n-butyloxy sub~kituted acid~, schemes B and C were ~o~md to be equ~lly suitabl~
~or the preparation of all corre~ponding Cl ~2 alkyl and alkoxy subskituted compounds.
~3327~
ample 5 Using schemes E and F shown in Figs 5 and 6, the steps o~ which are listed below, the compounds of ~ormula I listed in tables 4 and 5 were prepared.
Scheme E
( ) ~) -(ii) H0- ~ -CN
F
(lii) H0- ~ -CN
(iv) dicyclohexylcarbodilmide, 4-(N-pyrrol-idino)pyridine, C~l2Cl2 Scheme F
(i) H0 ~ - ~ -CN
F
(ii) H0~ CN
(iii) H0 ~ ~ -CN
In Fig~ 5 and 6, X is alkyl or alXoxy.
Th~ experimental method Nas as ~ollows~
A solu~ion of dicyclohexylcarbcdiimide ~DCC) ~1.15 n~l equlvalent) in dry dichlorGmethane (50 ml) ~as added dropwise to a stirred solution o~ the appropriate carboxylic acid ~1 mol equivalent), the appropriàte phenol ~1 mol ec~livalent) and 3 4-(N-pyrrolidino)pyridine ~0.30 mol equivalent! in dry dichloromethane ~55 ml) at room temperature. The mixture was stirred at room ;~
temperature overnight and the N,N'-dicyclohexylurea ~DCU) was filtered off. The filtrate was washed successively with water, 5% acetic acid, `
E~
13~27~
water and dried (MgS04). The solvent was removed in vacuo and the resid~e was purified by column chromatography (silica gel/dichloromethane) to give a solid which was recrystallised from ethanol (with charcoal decolourisation where requirecl) to yield colourless crystals.
A number of compounds of formula I were prepared, and are listed, together with their liquid crystal properties, in tables 4 and 5 below. The preparative routes which were employed lO to make the pheno3 and benzoic acid which were esterified using the DCC mediated method are also indicated in tables 4 and 5.
'Known' in table 4 and 5 indicates that commercially available or known acids or phenols were used.
Table 4 15 Structure R Acid Route Phenol Route R-N( c) K-I~ c) N-I( c) 1.1 C5Hll C D 29.5 (-8.0) 1.1 CgHgO C D _ 71.5 (7.5) 1.2 C5Hll C Known - 65.5 (32.0) 1.2 C4H90 C Known - 90.0 ~61.0) 1.3 C5Hll C Known - 39.5 (-3.0) 1~3 C4H90 C Known - 55.0 ~21.5) 1-4 C5Hll C D - 55.0 (-20.5) l.4 C~HgO C D - 68.5 ~60) l~S C5~111 B Known - 74.5 1-18.0]
1.5 C4RgO B Known - lOl.0 125.0]( 1~6 C5Hll B Known ~ 32.0 1-45.0]~
1~6 C41190 B Known - Sfi.0 ~-l.S) 1~7 C5~1ll B D - 36.5 ~-67) 1~7 C4HgO B D _ 63.0 ~-31.5) ~ ) represents monotropic transitions.
~332~
Table 5 Structure R Acid Route Phenol Route K-N( c) K-I~ c) NI( 1-8 C5Hll Known A 123.5 - 198.5 1.8C4HgO Known A 135.0 - 237.0 1.9C5~lll Known A 96.5 - 150.5 1.9C4HgO Known A 114.5 - 195.0 1.10C5Hll C Known 103.0 - 225.0 1.10C4HgO C Rnown 94.0 - 259.5 1.11C5Hll C A 112.5 - 187.5 1.11C4HgO C A 115.0 - 219,5 1.12C5Hll C A 98.0 - 1~3.5 1-12C4H90 C A 104.0 - 184.0 1.135 11 Known 109.5 - 191.0 1.13C~HgO ~ Known 94.0 - 223.0 1.145 11 116.5 - 158.0 1-14C4HgO B A 103 . o - 194. o 1.15C5qHll B A 89.0 - 121.0 1.15C4Hg ~ A 102.0 - 161.5 In Table 4, (i), (ii), (iii) indicate that the transitions observed were virtual, and were observed in 14, 13 and 21 wt~
mixtures o~ the compounds in the known nematic liquid crystal mixture E7 which has a composition:
2sn a5Hll~)~ CN 51 ~t~
n-a7H15~-~ CN 25 Nt%
R 17 ~ ~ 16 ~t56 n--C5~111~)--CN 8 wtS~
~33279iO
In table 6 belo~,l properties of various compounds of formula I
having the structures indicated (see table 1) are l;sted. The values of viscosity (~ cps), I and ~ ~ are extrapolated from a 10 weight % solution of the compound in a 1:1:1 by we1ght mixture of compounds of formula 3.8 (see table 3) having the R3:R4 combin~tions n-C3H7 :
2 5 3 7 5 11' n C5H11 : C2H5. These solutions are examples of liquid crystal mixtures of the invention.
Table 6 10 Structure R )1 Dipole l l.Z 6~L~ 8.6 39 1-3 ,, 7.1 10.~ 50.6 1.4 .. 7.7 10.0 64.9 1-5 ,. 6.8 7.9 36.3 1.6 .. 86 7.4 19.0 40.0 1.7 ,, 8.o 11.9 59.3 1.9 .. 420 7-5 10.0 54 1.1 n-c4Hgo 7 ~ 8 10 . 2 66. 8 1.2 ., 6.9 7.5 42,6 1.3 .. 7.5 10.7 L~3,~
1,4 8.o 11.3 6915 1.5 ,, 7.6 4L~,5 1.6 .. 7.9 9.9 ~-2 1.7 .. 8.3 10.7 58.. 5 ~3~7~
Referring to Fig 7, a liquid crystal electro optical display device comprises a layer of a liquid crystal material 31 between a front glass support plate 32 and a bac~ glass support plate 33.
rrhe front glass plate 32 is coated on the inner surEace thereof with a transparent conducting layer 34 eg tin oxide, to form an electrode. The back glass plate 33 is also coated on the inside surface thereof with a conductive layer 35. If light is to be transmitted through the device the back elactrode 15 and the back plate 33 are also transparent and made of the same materials as the front plate and electrode 32 and 34. If the device is to reflect light the back electrode 35 may be made reflective, ' eg of aluminium. rrhe front and back electrodes 34, 35 are coated with a transparent aligning layer 36, 37 eg of poly-vinyl alcohol which have each been rubbed prior to assembly of the device in a single rubbing direction. On assembly the rubbLng directions of the layers 36, 37 are arranged orthogonal to each other. In operation the electrodes 34, 35 are connected to a source of voltage (not shown~.
A suitable liquid crystal material 32 is a 14, 13l or 21 weight mixture of one of the compounds:
F
n-C5H~ coo~
F F
25 n-C~ cao ~ -CN
.
F
n~ail~H9o~-coo~ -CN
i ` , ` lF `
in the material E7 referred to above.
Mir3/2 2
P
A solution of n-butyllithium (10.5 M in hexane; 3.60 ml, 0.038 mol) was added dropwise to a stirred, cooled (-78C) solution 15 of com~ound 16 (7.00 g, 0.038 mol) in dry THF (35 ml) under dry nitrogen. The stirred mixture was maintained under these conditions for 2.5 h and then poured onto a slurry of solid carbon dioxide and dry ether~ The product was extracted into 10% sodiuun hydroxide which was then acidified with 36~ hydrochloric acid. The product was 2Q ~iltered off and dried ~CaCl2) in v~cuo to glve a colourless solid.
Yield 8~3 g, 96~.
mp 110-112 C.
~3~2~
Example 4: Scheme C
4-sutoxy-2-fluorobenzonitrile ~18). (Step 4C) A solution of 1-bramobutane (18.0 g, 0.13 mol) in acetone ~30 ml) was added dropwise to a stirred refluxing mixture of 2-fluoro-4-hydroxybenzonitrile (15.0 g, 0.11 mol) and potassium carbonate (46.0 g, 0.33 mol) in acetone (300 ml). The stirred mixture was heated under reflux for 21 h (glc analysis revealed absence of starting material). The product was extracted into ether (twice), and the combined ethereal extracts were washed with water, 5% sodium hydroxide, water and dried (MgSO4). The solvent and the excess of 1- bromobutane were removed _n vacuo to yield a pale-orange solid.
Yield 19-5 g, 93%-mp 25-26 C.
4-Butoxy-2-fluorob--enzo c acid (19)- (Step 3C) A mixture of concentrated sulphuric acid ~190 ml) and water (190 ml) was added dropwise to a stirred solution o~ campound 18 ~19~0 g, 0.098 mol) in glacial acetlc acid (380 ml). ~he stirred mixture was heated under re~lux for 48 h, cooled in a refrigerator ~or 24 h and the product was Eiltered oEf and dxied ~aCl2) in vacuo to givq pale-yellow crystals.
Yield 18.7 g, 90%.
mp 93-95 C.
- 313327~
2-Fluoro-4-pent~ rn-1'-ylbenzonitrile (20)- (Step lC) A solution of n-butyllitium (10.0 M in hexane; 10.0 ml, 0.10 mol) was added dropwise to a stirred, cooled (<0 C) solution of pent-1-yne (6.80 g, 0.10 mol) in dry THF (51 ml) under dry nitrogen. This mixture was stirred for 10 min and then a solution of zinc chloride (13.63 g, 0.10 mol) in dry T~ (100 ml) was added dropwise at <0 C. The mixture was stirred at room temperature for 15 min and a solution of compound 3 (20.0 g, 0.10 mol) in dry THF (100 ml) followed by a solution of tetrakis(triphenylphosphine)palladium(0) (2.31 g, 2.0 mmol) in dry THF (25 ml) were added dropwise at <0 C. The mixture was stirred at room temperature for 20 h (glc analysis revealed absence of starting material; 20 h was probablv longer than required for reaction) and poured into 10~ hydrochloric acid (200 ml). The product was extracted into ether (twice), and the combined ethereal extracts were washed with water, saturated sodium hydrogen carbonate, water and dried (MgSO4). The solvent was removed in v c o to af~ord an orange liquid which was distilled to yield a pale-yellow oil.
~O Yield 17.6 g, 94%.
bp 100-105 C at ~.1 mm Hg.
Note.
* Sodium dried THF was distilled from lithium aluminium hydride and kept over a molecular sieve (type 4A).
Zinc chloride (ACS reagent) was dried overnight at 100 C~
~3327~
2-Fluoro-4-pentylbenzonitrile (21). (Step 2C) A stirred mixture of compound 20 (16.0 g, 0.085 mol~ and 5%
palladium-on-charcoal (4.00 g) in ethanol (100 ml) was hydrogenated at atmospheric pressure for 8 h (glc analysis revealed absence of starting material). The catalyst was filtered off and the solvent was removed in vacuo to yield a pale-orange semi-solid.
Yield 15.35 g, 95%.
mp not recorded, probably around 20 &.
2-Fluoro-4-pentylbenzoic acid (22). (St~p 3C) A mixture of concentrated sulphuric acid (150 ml) and water (150 ml) was added dropwise to a stirred solution of compound 21 (15.0 g, 0.078 mol) in glacial acetic acid (300 ml). The stirred mixture was heated under reflux for 48 h, cooled in a refrigerator overnight and the product was filtered off. The product was dissolved in ether, extracted into 10% sodium hydroxide, which was then acidified with 3Z% hydrochloric acid, washed with ether (twice), and the combined ~thereal phases were washed with water and dried ~MgSO~). The solvent was removed in vacuo to give a brown crystalline solid.
Yield 11.5 g, 70%.
mp 90-91 &.
,~ 13327A~
2l~
4-Butoxy~enzoic acid (23).(Step 5C) 1-Bromobutane (22.6 g, 0.165 mol) was added dropwise at room temperature to a stirred mixture of 4-hydroxybenzoic acid (15.0 g, 0.11 mol) in ethanol (60 ml) and sodium hydroxide (10.60 g) in the minimum amount of water. The stirred mixture was heated under reflux overnight (tlc analysis revealed a complete reaction), and then the ethanol was distilled off and an equal volume o~ water was added.
The mixture was boiled to give a solution, cooled, washed with ether and acidified with 36% hydrochloric acid. The cooled mixture ~s filtered, and the product was ~ashed with water to give a colourless solid (13.9 g) which was recrystallised from ethanol to give colourless crystals.
Yield 12.1 g, 57~.
mp 149-150 C.
Although illustrated in examples l, 2, 3 and 4 abova, and in Fig~ 1, 2, 3 and 4 for -the preparation o~ the n-pentyl and n-butyloxy sub~kituted acid~, schemes B and C were ~o~md to be equ~lly suitabl~
~or the preparation of all corre~ponding Cl ~2 alkyl and alkoxy subskituted compounds.
~3327~
ample 5 Using schemes E and F shown in Figs 5 and 6, the steps o~ which are listed below, the compounds of ~ormula I listed in tables 4 and 5 were prepared.
Scheme E
( ) ~) -(ii) H0- ~ -CN
F
(lii) H0- ~ -CN
(iv) dicyclohexylcarbodilmide, 4-(N-pyrrol-idino)pyridine, C~l2Cl2 Scheme F
(i) H0 ~ - ~ -CN
F
(ii) H0~ CN
(iii) H0 ~ ~ -CN
In Fig~ 5 and 6, X is alkyl or alXoxy.
Th~ experimental method Nas as ~ollows~
A solu~ion of dicyclohexylcarbcdiimide ~DCC) ~1.15 n~l equlvalent) in dry dichlorGmethane (50 ml) ~as added dropwise to a stirred solution o~ the appropriate carboxylic acid ~1 mol equivalent), the appropriàte phenol ~1 mol ec~livalent) and 3 4-(N-pyrrolidino)pyridine ~0.30 mol equivalent! in dry dichloromethane ~55 ml) at room temperature. The mixture was stirred at room ;~
temperature overnight and the N,N'-dicyclohexylurea ~DCU) was filtered off. The filtrate was washed successively with water, 5% acetic acid, `
E~
13~27~
water and dried (MgS04). The solvent was removed in vacuo and the resid~e was purified by column chromatography (silica gel/dichloromethane) to give a solid which was recrystallised from ethanol (with charcoal decolourisation where requirecl) to yield colourless crystals.
A number of compounds of formula I were prepared, and are listed, together with their liquid crystal properties, in tables 4 and 5 below. The preparative routes which were employed lO to make the pheno3 and benzoic acid which were esterified using the DCC mediated method are also indicated in tables 4 and 5.
'Known' in table 4 and 5 indicates that commercially available or known acids or phenols were used.
Table 4 15 Structure R Acid Route Phenol Route R-N( c) K-I~ c) N-I( c) 1.1 C5Hll C D 29.5 (-8.0) 1.1 CgHgO C D _ 71.5 (7.5) 1.2 C5Hll C Known - 65.5 (32.0) 1.2 C4H90 C Known - 90.0 ~61.0) 1.3 C5Hll C Known - 39.5 (-3.0) 1~3 C4H90 C Known - 55.0 ~21.5) 1-4 C5Hll C D - 55.0 (-20.5) l.4 C~HgO C D - 68.5 ~60) l~S C5~111 B Known - 74.5 1-18.0]
1.5 C4RgO B Known - lOl.0 125.0]( 1~6 C5Hll B Known ~ 32.0 1-45.0]~
1~6 C41190 B Known - Sfi.0 ~-l.S) 1~7 C5~1ll B D - 36.5 ~-67) 1~7 C4HgO B D _ 63.0 ~-31.5) ~ ) represents monotropic transitions.
~332~
Table 5 Structure R Acid Route Phenol Route K-N( c) K-I~ c) NI( 1-8 C5Hll Known A 123.5 - 198.5 1.8C4HgO Known A 135.0 - 237.0 1.9C5~lll Known A 96.5 - 150.5 1.9C4HgO Known A 114.5 - 195.0 1.10C5Hll C Known 103.0 - 225.0 1.10C4HgO C Rnown 94.0 - 259.5 1.11C5Hll C A 112.5 - 187.5 1.11C4HgO C A 115.0 - 219,5 1.12C5Hll C A 98.0 - 1~3.5 1-12C4H90 C A 104.0 - 184.0 1.135 11 Known 109.5 - 191.0 1.13C~HgO ~ Known 94.0 - 223.0 1.145 11 116.5 - 158.0 1-14C4HgO B A 103 . o - 194. o 1.15C5qHll B A 89.0 - 121.0 1.15C4Hg ~ A 102.0 - 161.5 In Table 4, (i), (ii), (iii) indicate that the transitions observed were virtual, and were observed in 14, 13 and 21 wt~
mixtures o~ the compounds in the known nematic liquid crystal mixture E7 which has a composition:
2sn a5Hll~)~ CN 51 ~t~
n-a7H15~-~ CN 25 Nt%
R 17 ~ ~ 16 ~t56 n--C5~111~)--CN 8 wtS~
~33279iO
In table 6 belo~,l properties of various compounds of formula I
having the structures indicated (see table 1) are l;sted. The values of viscosity (~ cps), I and ~ ~ are extrapolated from a 10 weight % solution of the compound in a 1:1:1 by we1ght mixture of compounds of formula 3.8 (see table 3) having the R3:R4 combin~tions n-C3H7 :
2 5 3 7 5 11' n C5H11 : C2H5. These solutions are examples of liquid crystal mixtures of the invention.
Table 6 10 Structure R )1 Dipole l l.Z 6~L~ 8.6 39 1-3 ,, 7.1 10.~ 50.6 1.4 .. 7.7 10.0 64.9 1-5 ,. 6.8 7.9 36.3 1.6 .. 86 7.4 19.0 40.0 1.7 ,, 8.o 11.9 59.3 1.9 .. 420 7-5 10.0 54 1.1 n-c4Hgo 7 ~ 8 10 . 2 66. 8 1.2 ., 6.9 7.5 42,6 1.3 .. 7.5 10.7 L~3,~
1,4 8.o 11.3 6915 1.5 ,, 7.6 4L~,5 1.6 .. 7.9 9.9 ~-2 1.7 .. 8.3 10.7 58.. 5 ~3~7~
Referring to Fig 7, a liquid crystal electro optical display device comprises a layer of a liquid crystal material 31 between a front glass support plate 32 and a bac~ glass support plate 33.
rrhe front glass plate 32 is coated on the inner surEace thereof with a transparent conducting layer 34 eg tin oxide, to form an electrode. The back glass plate 33 is also coated on the inside surface thereof with a conductive layer 35. If light is to be transmitted through the device the back elactrode 15 and the back plate 33 are also transparent and made of the same materials as the front plate and electrode 32 and 34. If the device is to reflect light the back electrode 35 may be made reflective, ' eg of aluminium. rrhe front and back electrodes 34, 35 are coated with a transparent aligning layer 36, 37 eg of poly-vinyl alcohol which have each been rubbed prior to assembly of the device in a single rubbing direction. On assembly the rubbLng directions of the layers 36, 37 are arranged orthogonal to each other. In operation the electrodes 34, 35 are connected to a source of voltage (not shown~.
A suitable liquid crystal material 32 is a 14, 13l or 21 weight mixture of one of the compounds:
F
n-C5H~ coo~
F F
25 n-C~ cao ~ -CN
.
F
n~ail~H9o~-coo~ -CN
i ` , ` lF `
in the material E7 referred to above.
Mir3/2 2
Claims (21)
1. A compound having a general formula I:
Formula I
in which R is R1, R1O or R1COO, where R1 is C1-12 alkyl, n and m are 0 or 1 provided that (n + m) is 0 or 1, each of a, b, c and d are independently 0 or 1,provided (a + b + c + d) is not zero, but excluding the case where a and b are O and m is O and one of c or d is O.
Formula I
in which R is R1, R1O or R1COO, where R1 is C1-12 alkyl, n and m are 0 or 1 provided that (n + m) is 0 or 1, each of a, b, c and d are independently 0 or 1,provided (a + b + c + d) is not zero, but excluding the case where a and b are O and m is O and one of c or d is O.
2. A compound according to claim 1 characterised by a formula:
3. A comound according to claim 1 characterised by a formula:
4. A compound according to claim 1 characterised by a formula:
5. A compound according to claim 1 characterised by a formula:
6. A compound according to claim 1 characterised by a formula:
7. A compound according to claim 1 characterised by a formula:
8. A compound according to claim 1 characterised by a formula:
9. A compound according to claim 1 characterised by a formula:
10. A compound according to claim 1 characterised by a formula:
11. A compound according to claim 1 characterised by a formula:
12. A compound according to claim 1 characterised by a formula:
13. A compound according to claim 1 characterised by a formula:
14. A compound according to claim 1 characterised by a formula:
15. A compound according to claim 1 characterised by a formula:
16. A compound according to claim 1 characterised by a formula:
17. A compound according to any one of claims 1 to 16 characterised in that R contains from 3 to 8 carbon atoms in-clusive.
18. A compound according to claim 17 characterised in that R1 is n-alkyl or an asymmetrically substituted alkyl group.
19. A compound according to any one of claims 1 to 16 characterised in that R is n-alkyl or n-alkoxy.
20. A liquid crystal material being a mixture of compounds, characterised in that at least one is a compound of formula I as claimed in claim 1.
21. A nematic liquid crystal display device characterised in that it uses a liquid crystal material as claimed in claim 20.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB888804330A GB8804330D0 (en) | 1988-02-24 | 1988-02-24 | Laterally fluorinated 4-cyanophenyl & 4-cyanobiphenyl benzoates |
| GB8804330 | 1988-02-24 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1332740C true CA1332740C (en) | 1994-10-25 |
Family
ID=10632301
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000591980A Expired - Fee Related CA1332740C (en) | 1988-02-24 | 1989-02-24 | Laterally fluorinated 4- cyanophenyl and 4'- cyanobiphenyl bensoates |
Country Status (8)
| Country | Link |
|---|---|
| US (2) | US5156763A (en) |
| EP (1) | EP0407438B1 (en) |
| JP (1) | JP2863235B2 (en) |
| KR (1) | KR0131146B1 (en) |
| CA (1) | CA1332740C (en) |
| DE (1) | DE68920429T2 (en) |
| GB (1) | GB8804330D0 (en) |
| WO (1) | WO1989008102A1 (en) |
Families Citing this family (25)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1991003447A1 (en) * | 1989-09-05 | 1991-03-21 | MERCK Patent Gesellschaft mit beschränkter Haftung | Difluorobenzonitriles and liquid-crystal medium |
| DE4000535B4 (en) * | 1989-12-06 | 2005-11-03 | Merck Patent Gmbh | 1,4-disubstituted 2,6-difluorobenzene compounds and liquid-crystalline medium |
| EP0502154A1 (en) * | 1990-09-26 | 1992-09-09 | MERCK PATENT GmbH | Fluorobenzene derivatives |
| GB2250748A (en) * | 1990-12-13 | 1992-06-17 | Secr Defence | Liquid crystal mixtures |
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| US4029594A (en) * | 1976-06-17 | 1977-06-14 | Rca Corporation | Novel liquid crystal compounds and electro-optic devices incorporating them |
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| EP0019665B2 (en) * | 1979-05-28 | 1987-12-16 | MERCK PATENT GmbH | Liquid-crystal compositions |
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-
1988
- 1988-02-24 GB GB888804330A patent/GB8804330D0/en active Pending
-
1989
- 1989-02-21 DE DE68920429T patent/DE68920429T2/en not_active Expired - Lifetime
- 1989-02-21 EP EP89904111A patent/EP0407438B1/en not_active Expired - Lifetime
- 1989-02-21 JP JP1503580A patent/JP2863235B2/en not_active Expired - Lifetime
- 1989-02-21 US US07/571,590 patent/US5156763A/en not_active Expired - Lifetime
- 1989-02-21 WO PCT/GB1989/000178 patent/WO1989008102A1/en active IP Right Grant
- 1989-02-21 KR KR1019890701947A patent/KR0131146B1/en not_active IP Right Cessation
- 1989-02-24 CA CA000591980A patent/CA1332740C/en not_active Expired - Fee Related
-
1992
- 1992-05-12 US US07/881,670 patent/US5334327A/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| EP0407438A1 (en) | 1991-01-16 |
| KR0131146B1 (en) | 1998-04-13 |
| WO1989008102A1 (en) | 1989-09-08 |
| DE68920429T2 (en) | 1995-05-24 |
| JPH03503637A (en) | 1991-08-15 |
| US5334327A (en) | 1994-08-02 |
| DE68920429D1 (en) | 1995-02-16 |
| US5156763A (en) | 1992-10-20 |
| EP0407438B1 (en) | 1995-01-04 |
| JP2863235B2 (en) | 1999-03-03 |
| KR900700439A (en) | 1990-08-13 |
| GB8804330D0 (en) | 1988-03-23 |
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