DE2527638A1 - PROCESS FOR PRODUCING DIPYRIDILIUM COMPOUNDS - Google Patents

Description

PATENT AGENCY OFFICE TEL. (089) 53 96 53-56 TELEX: 524845 tlpat CABLE ADDRESS: Germaniapatent Munich

8000 Munich 2 Bavariaring 4

P.O. Box 202403 June 20, 1975
B 6694 - case Q.27098

IMPERIAL CHEMICAL INDUSTRIES LIMITED
London, UK

Process for the production of
Dipyridilium compounds

The invention relates to a process for the preparation of compounds having a Dipyridiliurakern and it includes compounds obtained thereafter.

Connections of the structure:

2X

are known and examples are given in GB-PS 1,310,812 specified by the applicant.

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The present invention now relates to a process for the preparation of dipyridiliura compounds of the formula

2X

1 10
in which R to R are hydrogen, F, Cl or organic Substi

1 are tuents. Preferably at least one of the radicals is R

and R ⁵ and / or R ⁶ and R ¹⁰ are H and R ¹¹ and R ¹² are organic substituents, at least one of which is formed by a phenyl group which is bonded to an alkyl radical having 2 to 12 carbon atoms, -COOR ^J (where R ^ is an alkyl group with 1 to 10 carbon atoms, an aryl group or hydrogen), an amide group, hydroxyl,

- N = N -

or halogen

is substituted or a polycyclic ^, aromatic group such as naphthyl, which may optionally have substituents, and although in particular electron-withdrawing radicals in the para position to the point of attachment of the aromatic nucleus to the nitrogen the heterocyclic ring; X ~ is one of an acid and preferably of a strong mineral acid with a pKa of less than 2.5 or an organic acid

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directed anion.

The two aromatic rings are usually linked to one another in 2.2 'positions or preferably in 4.4' positions, replacing the radicals R ⁵ 'or B?' for example with the formation of 2,2'-dipyridylene and 4,4'-dipyridylene.

I 10

As specific examples of the radicals R to R are

Mention should be made of alkyl, especially C ₁ - to C _{12 -alkyl (preferably C 1} - C 1), aryl, aralkyl, alkaryl and oxyhydrocarbyl groups, as are mentioned in the above-mentioned GB-FS. Bulky or large groups, which sterically interfere with the synthesis or use of such compounds, should preferably be avoided and groups that can be easily reducible, such as NOp, should preferably be absent.

II 12 As specific examples of the radicals R and R

the following can be mentioned:

Phenyl; - (Jy-X with X = F, Cl, Br or J; - / ^ \ - 0 - / ^ S; - (C)> - c- / ~ \; - (j ^) - ^R with R = CH ,, -C ₅ H _1. Or nC, H _Q ;

\ / ι ι Vw · / γ γ O £ * -J "Z /

/ ^ _x / ^ TV CH ₃ -

'-QC-CH ₃ ; -Q-NO ₂ ;

and -Γ ^ -NHCOCH ₃ .

(J - ~ - CH ₃ .

Inorganic ion A _n include F ", Cl", Br ~, SO., "MeSO ^ (Niederalkylsulfat) chlorate, perchlorate, BF ^"

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2B27638

NO, and sulfonates.

Organic anions include acetate, citrate, tartrate, Formate, maleate, oxalate and anions of other water-soluble Mono-, di- and tricarboxylic acids, especially those that contain hydroxyl groups.

It should be noted that the compounds listed above are examples (although not exhaustive) of Are compounds that can be prepared by the process of the invention.

According to the invention, a method for the production of compounds with a dipyridilium nucleus is proposed, that is, bringing together an N, N'-bis (2,4-dinitrophenyl) -4,4'-dipyridilium salt (hereinafter referred to as DNP) with a primary aromatic amine, that is substituted with a group that of those

11 12 corresponds to those in the compound in the R or R position should be introduced, being in a polar, preferably aqueous medium is worked.

Preferred salts which are used according to the invention are halides, in particular fluorides and chlorides and also alkyl sulfates, in particular lower alkyl (C 1-4) sulfates such as methyl and ethyl sulfates.

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The product yield is among other things by the ratio of the amine to DNP. At least 4 moles of amine are used per mole of DNP salt, the more preferred Ratio is 5 to 6 moles per mole of DNP salt. The upper limit is not critical, but it should not be about 10: 1.

The medium used should be inert, i.e. such that it does not interact with the reactants or products chemically reacts. A medium is used that is able to dissolve an ionic material. It should too have a high (e.g.> 75% by weight) solubility for the amine (which, however, does not necessarily have to be complete). The medium is preferably water, optionally mixed with a water-miscible polar solvent (with a high Dielectric constants of, for example, more than 15). The medium used should not have any tendency to induce a separation of ionic and non-ionic reactants, which leads to an uptake of essential fractions of the amine in the non-ionic phase, examples of water-miscible, polar solvents that are used are alcohol (e.g. ethanol, methanol, propanol), dimethylformamide and acetonitrile.

The reaction is expediently carried out at a temperature at which the medium reaches reflux conditions,

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which is expediently not higher than about 16O C; preferably the reaction is not carried out below about 50 ° C. It is to be noted that not all of the arain need be in solution, but a part at a time before it reacts, may be in suspension, with dissolution taking place as the reaction proceeds. An implementation an inert atmosphere such as nitrogen is preferred, but is not necessarily essential. The ionic reactant is preferably completely dissolved in the medium.

The reaction time is usually in the region of 0.5 to A hours. At the end of the response time, the Solution cooled and some crude product may crystallize out.

The remaining product can be mixed with a water-immiscible organic solvent such as chloroform or toluene is extracted and still further product can be obtained by evaporating the aqueous solution. The resulting solid material contains the product, starting material, intermediates and 2, A-dinitroaniline.

Dissolving or digesting the solids in hot alcohol, preferably hot ethanol, leads to dissolution of the unreacted amine and of non-ionic pro-

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ducts and supports the conversion of intermediate products into the product that is not very common in ethanol is soluble.

The product can be recrystallized from glacial acetic acid. In this case, a crystalline product is obtained which contains the acetic acid, which can usually be removed by vacuum drying at at least 80 ⁰ C. The further purification expediently comprises one or more of the steps of dissolving the solid in hot water, decolouring the solution with activated charcoal and precipitating the material from concentrated solution at an elevated temperature of usually about 60 ° C by adding three to five times its value Volume of acetone, isobutanol or acetonitrile.

Some of the connections described above are new

same:

11 12 and these include compounds in which R or R

CH-,

^CH 3

CN,

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or (' ^λ ) NH co CH ₃ .

The ring or the rings can carry one or more substituents, which are preferably lower alkyl radicals, especially having 1 to 3 carbon atoms, although it is particularly preferred that additional substituents are added the above are missing.

In particular, are the weak gxy acid salts (mono-, di- or tricarboxy) of all of the above-mentioned dipyridilium compounds new, especially the citrates and tartrates.

The compounds according to the invention can be used, for example, in devices in which the Property of connection, on a passage of electrical Current through a solution of the connection to react reversibly, is exploited. This appearance depends on the fact that the dication in a suitable solvent, especially in aqueous solution, electrochemically can be reduced to a strongly colored, water-insoluble or only slightly water-soluble radical cation. The education of the radical cation takes place at a cathode and that

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Radical cation tends to remain associated with this, usually as one deposited on the electrode Solid layer. The deposition of the radical cation can be removed from the cathode by oxidation, either chemically or by reversing the polarity of the electrode, wherein the cation radical is reoxidized to the soluble and (usually) much less colored dication.

In particular, the compounds can find application in electrochromic display devices and systems, such as see applicants' earlier US Pat. No. 3,712,709 and British Pat. No. 1,302,000 and in the pending UK patent applications 12904/73 and 48079/73 of the applicant are described.

When A application _n in a elektrcchromen device of the type described, the electrodes are used in relation to the chemically inert in contact with the electrolyte and may zBMetallen of any suitable material such as gold and platinum, electrically conductive glasses or glass or other substrate with an electrically conductive inert surface such as for example, a thin metal film exist or be formed. A small potential difference is usually adequate to effect the reduction; the applicant prefers the application of voltages in the

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- ίο - 2527630

Area from 0.5 to 3 V.

The application of the process according to the invention in the preparation of p-cyanophenyl-dipyridilium salts is described in the Original application not claimed.

Example 1 r- O ^C1 Preparation of

Il

A hot solution (80-90 C) with N, N'-bis- (2,4-dinitrophenyl), 4'-dipyridiliumdichlorid (56.1 parts) (400 parts) was added in water over a period of time of 20 minutes, the reaction mixture was stirred vigorously -4. The mixture was refluxed for an additional hour and then cooled to room temperature. The reaction mixture was then poured into stirred acetone (4000 parts) whereupon a fawn colored solid precipitated. The precipitated solid was collected by filtration, carefully put on the filter with boiling dry. Washed acetone and dried in vacuo at 60 ° C. Yield: 48 parts or 81.5 %>

The crude solid was dissolved in hot water (50 parts) dissolved and the solution treated with activated charcoal and

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removal of the charcoal filtered. The filtrate was in vacuo

slowly evaporated to dryness giving a self

at 270 ° C decomposing dihydrate in the form of a pale yellow crystalline solid.

Yield = 74.5 %.

Elemental analysis values:

Calcd for C ₅₆ H ₃₀ N ₂ C ₂ Cl ₂ : C: 69.2; H: 4.8; N: 4.48;

0: 10.23; Cl: 11.27 % Found: C: 69.45; H: 5.07; N: 4.48;

0: 10.37; Cl: 11.63 %.

Example 2

Production of N, N ¹ -Bis- (pn-butylphenyl) -4,4'-dipyridilium-

dichloride η C - {^ \ -N ⁷ "^ -

Cl "

A hot solution of DNP (28 parts) in water (75 parts) was added dropwise to a refluxing unit Solution of p-n-butylaniline (37.5 parts) in water (25 parts) and dimethylformamide (50 parts) were added over a period of 20 minutes. Then the Mixture held at reflux conditions for an additional 2 hours. On cooling, the deposited blackish-purple solid was filtered off and the aqueous filtrate evaporated to dryness on a rotary evaporator in vacuo to give an additional amount of solid product.

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. _12th

2527838

The combined solids were digested with boiling ethanol (150 parts) and the warm mixture in poured stirring acetone (500 parts), whereupon a fawn solid separated out. This was filtered off and washed with acetone until the washing liquid was almost colorless and then off after treatment with activated charcoal Recrystallized glacial acetic acid. The crystallized yellow solid contained "crystal acetic acid". The crude product was in dissolved in a minimal amount of boiling water, again treated with activated charcoal to produce an almost colorless one aqueous solution that was slowly poured into excess, stirred acetone.

The precipitated almost white microcrystalline solid was filtered off, washed with dry acetone and then with ether and finally dried in vacuo at 60 ° C. for k hours, v / obei 23 parts of a dihydrate salt were obtained. Yield: 87%.

Elemental analysis values: calculated for C ₃₀ H ₃₈ N ₂ C

found*.

: C: 68.0; H: 7.2; N: 5.3; Cl: 13.4; 0: 6.1 % C: 67.7; H: 7.5; N: 5.7; Cl: 13.4; 0: 5.6 %.

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Examples 3 to 21

The procedure of Example 1 was generally repeated as described except that given in the example Amine was replaced by the amines given in Table 1. The proportions of the reactants - A'nin, DNP and Solvents - are also specified with the product in each case.

Table 2 shows the colors of the cation radicals derived from the diquaternary compounds.

20 ml samples of 0.01 molar aqueous solutions of the run quaternary salts of 4,4'-dipyridyl with 0.1 mol / l Tetraethylammcniumchlorid (added to increase the electrical conductivity of the solution) were regarding tested the electrochemical generation of their respective cation radicals. The tension at which the radical cation and its color are given below for Au and Pt electrodes (see Tab. 2).

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Table 1

α * α co co

DNP reaction with primary aromatic amines

Example no.

10

Amine

aniline

p-fluoro aniline

p-chloroaniline

p-bromoaniline

p-iodaniline

p-methyl aniline

p-Ethy! aniline

p-n-Buty! aniline

Parts by weight
Amine

232.5

227

318.8

430

547.5

267.5

302 _; 5

375

Parts by weight DNP

2 80.5

280.5

2 8O ₇ 5

280.5

2 80.5

280.5

28O _; 5

28O ₇ 5

Solvents and
Gew, -tei2ß

DMF, 750 H ₂ O, 1100

DMF, 100 H ₂ O, 1800

DMF, 150 H ₂ O, 225

DMF, 250 H ₂ O, 1300

DMF, 250 H ₂ O, 850

DMF, 100 H ₂ O, 2000

, 2000

DMF, 500 H ₂ O, 1000

R ¹¹ = R ¹²

2C1 ~

-Cl

-V // " ^Br

W " ^CH 3

W.

ro

CD

cc

DMF = dimethylformamide.

Cont.

11 12

15 16 17 18 19

20th

21

p-amino benzoic acid

p-ethyl amino benzoate

p-amino-benz amide

p-nitro-aniline

2,4,6-trimethyl aniline

4-amino-benzophenone

4-amino-acetophenone

p-phenoxy-aniline

l-amino-4-cyanonaphthalene

p-azophenyl aniline

p-amino-acetanilide

342.5

412.5

340

345

337.5

985

135.2

185

420

492.5

375

280.5

280.5

280.5

28O. _; 5

280.5

561

112.2

112.2

280.5

280.5

280.5

DMF, 200 H ₂ O, 1150

DMF, 1250 H ₂ O, 1250

DMF, 200 H ₂ O, 1200

DMF, 200 H _o 0.1700

, 2000

DMF, 3000 H ₂ O, 9000

DMF, 500 H ₂ O, 1500

DMF, 500 H ₂ O, 1500

DMF, 500 H ₂ O, 1500

DMF, 400 H ₀ O, 800

DMF, 250 H ₂ 0.100

-Q-

COOH

VN, / "COOC ₂ H ₅

\ x, / - CONH ₂

Vx > / - ^m 2

CH.

- "W-CH CH - ^ - ^ ^J

-C \ -t

CH.

- <w> CN

"\ w) -NHCOCH ₃

he

ro

cn co cc

2 b 2 7 6 3 8

Table 2

example Voltage (V) platinum Radical color gold platinum No. gold 1.5 very dark green golden brown . 3 1.5 1.3
1.5 deep chestnuts
brown, almost
black
dark green deep chestnuts
Brown
green 4th
5 1.4
1.2 Ί, ο very dark green dark green 6th 1.0 n.e. n.e. n.e. 7th n.e. 1.2 black Red Black 8th 1.4 1.0 very dark red
nearly black red-brown 9 1.0 1.5 very dark green nearly black 10 2.0 n.e. dark green 11 n.e. 1.3 green green 12th 1.3 n.e. dark green 13th n.e. 1.8 green green IA 2.0 1.8 dark green gold-orange 15th 1.8 1.0 nearly black nearly black 16 1.0 1.3 dark green dark green 17th 1.0 1.0 nearly black black 18th 1.0 n.e. dark green - 19th n.e. - - - 20th - 2.0 appears
black in
red salt nearly black 21 2.0

Comment: n.e. = not available

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2b27638

The preparation of compounds with anions, different than those given in the previous examples can be conveniently achieved, for example, by ion exchange as follows will:

(1) Using anion exchange resins such as "Deacidite FFIP" (supplied in chloride form by Permutit Co.), which can be exchanged with a suitable anion such as fluoride. The one you want Anion-bearing resin can then be used to exchange the anion with the dipyridylium salt (usually in Chloride form) can be used against the anion of the resin.

(2) Use of ammonic acid (4,4'-diamino-stilbene-2,2'-disulfonic acid. As diammonium salt): The water-soluble ammonium amsonate can be reacted in aqueous solution with the dipyridylium salt to form dipyridilium amsonate, a very sparingly soluble salt ₇ which e.g. corresponds to the formula:

- CH = CH - ^ 3 ~ ^NH 2

This salt can be mixed with mineral acids or carboxylic acids, which are stronger acids than amsonic acid, with precipitation

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of ammonic acid in aqueous solutions are converted into where the dipyridylium salt of this acid is soluble.

It was mentioned above that the new compounds according to the invention or by the process according to the invention Compounds obtained can be applied in devices in which a color change of an electrode by passing a current through a solution of the compound and the present invention thus includes devices that a solution of a new connection described here or one after the described Method obtained compound together with two or more inert electrodes and means for connection These contain electrodes with a source of electricity, with the help of which an electric current is generated a color change can be sent through the solution by reducing the cation. Advantageously includes the solution as described in one or more of the above patents and patent applications, an auxiliary redox system, whereby an electrochemical oxidation of the reduced colored components is facilitated.

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Claims (10)

Claims 11 1. Process for making one in the R - and / or 12th
R position substituted compound with a dipyridilium core of the formula characterized in that a Ν, Ν'-bis (2,4-dinitrophenyl) -4, A'-dipyridilium salt is _{brought into contact with a primary aromatic atom n} which is substituted with a group corresponding to that of in 11 1? the compound introduced in R and / or R position shall be. 2. The method according to claim 1, characterized in that the reaction is carried out in a polar medium. 3. The method according to claim 1 or 2, characterized in that the salt is a halide or an alkyl sulfate. 4. The method according to any one of the preceding claims, characterized in that the molar ratio of amine to Salt is chosen within the range of 4: 1 to 10: 1. 5. The method according to any one of the preceding claims, characterized in that the reaction medium is water 609819/1200 along with another inert, polar, liquid Medium includes. 6. The method according to any one of the preceding claims, characterized in that the reaction at the reflux temperature of the medium. 7. Connection with a Dipyridiliumkern, which is in the R and / or R position with the radicals N or NH CO CH- is substituted. 8. Dipyridilium compound, characterized in that it is the salt of a weak hydroxy acid and in particular of tartaric acid or citric acid. 9. Device in particular with utilization of the electrochromic effect, characterized by a content of a compound obtained according to any one of claims 1 to 6. 609819/1200 10. The device according to claim 9, characterized by a content of a compound according to claim 7 or 8. 609819/1200