DE1238894B - Process for the preparation of tetracyano-benzoquinone- (1, 4) - Google Patents

Description

Process for the preparation of tetracyanobenzoquinone- (1, 4) The present Invention relates to a process for the preparation of tetracyano-benzoquinone- (1,4) from 2,5-dicyano-3,6-dihalogenobenzoquinones.

According to reports from the German Chemical Society, 44, S. 3469 (1911), is said to be in the implementation of chloranil with potassium cyanide in 850 /, the Methanol 2,5-dihydroxy-3,6-dicyano-benzoquinone- (1,4), the so-called cyanilic acid, develop.

The connection established in this way, however, was found during the follow-up examination proved to be 2,3-dicyan-5,6-dichlorohydroquinone. It has continued to be on its own Studies have shown that the introduction of further cyano groups in 2,3-dicyan-5,6-dihaloquinones and 2,3-dicyan-5,6-dihalohydroquinones fail.

It has now been found, surprisingly, that tetracyano-benzoquinone- (1,4) can be prepared in such a way that one is on a 2,5-dicyan-3,6-dihalo-benzoquinone- (l , 4) a) simultaneously a lower aliphatic alcohol and an alkali metal cyanide or Alkaline earth cyanide or b) first a lower aliphatic alcohol and then on the 2,5-dicyano-3,6-dialkoxy-benzoquinone- (1,4) obtained in this way is an alkali metal cyanide or Alkaline earth cyanide is allowed to act or that c) first a 2,5-dicyan-3,6-dihalogenobenzoquinone- (1,4) or by the action of hydrogen halide on 2,5-dicyano-benzoquinone- (1,4) reaction product obtained hydrolyzed to cyanilic acid, this in a known manner dialkylated to give a 2,5-dicyan-3,6-dialkoxy-benzoquinone- (1,4) and thereupon an alkali metal cyanide or alkaline earth metal cyanide is allowed to act or that d) a 2,5 - dicyanide - 3,6 - dihalogen - benzoquinone - (1,4) or one of it by the action of a lower one aliphatic alcohol obtained according to b) 2,5-dicyano-3,6-dialkoxy-benzoquinone- (1,4) by treating with ammonia, a primary or secondary amine into a corresponding one 2,5-dicyano-3,6-diamino-benzoquinone derivative converted and then an alkali metal cyanide or alkaline earth cyanide act in the presence of a lower aliphatic alcohol leaves and the tetracyano-hydroquinone thus obtained by treatment with nitrous gases converted into tetracyane-benzo quinone- (1,4).

Compound I reacts with anhydrous alcohols in the cold slowly, when heated quickly with the formation of 2,5-dicyan-3,6-dialkoxy-benzoquinone (III) that when heated with an alkali or alkaline earth cyanide in an alcohol passes into the corresponding salt of compound II. To the same connection one arrives immediately if one simultaneously uses an alkali or alkaline earth cyanide and an alcohol to act. The hydroquinone derivative (II) is oxidized to quinone (IV) by nitrous gases.

Another variant of the method of the invention consists in that the compound 1 is first mixed with water to give 2,5-dicyano-3,6-dihydroxy-benzoquinone- (1,4), the actual "cyananilic acid", hydrolyzed, this z. B. by means of diazomethane converted into the dimethoxy derivative corresponding to the formula III and then further implemented in the manner described above.

The cyananilic acid can also be obtained in such a way that one on by oxidation of 2,5-dicyanohydroquinone with z. B. nitrous gases obtained 2,5-Dicyan-benzoquinone- (1,4) hydrogen halide can act and the resulting Hydrolyzed reaction product.

The course of the reaction is illustrated using the scheme below, radical of a primary or secondary amine or the alkali or alkaline earth metal: in which R is a lower aliphatic radical, N <the ammonia radical, X is a halogen atom and Me 0 O OH O CN CN X l CN a) NC | CN NC MeCN RAW, \ </ nitrous, II to ROH, OH gases ~ NC NC0X X NC OO OH O HX lc) t / in IV HO ib), ROH b) ROecHn d) MeCN o 0 o CN || CN R z. CH-, N j! 1 / CN Nc0i! Glt NC 0 0 Cyananilic acid III Another way to produce tetracyano-hydroquinone is to use 2,5-dicyano-3,6-dibromobenzoquinone- (1,4) or 2,5-dicyano-3,6-dialkoxybenzoquinone- (1,4) ( III) to convert primary or secondary amines into the corresponding 2,5-dicyano-3,6-diaminoquinones by treatment with ammonia, treat them with alkali or alkaline earth cyanides in the presence of lower aliphatic alcohols and then, as explained above, to give the quinone IV to oxidize.

To prepare the 2,5-dicyan-3,6-diamino derivatives, primary or secondary amines or ammonia can be used. For example, let morpholine, Piperidine, pyrrolidine, hexylamine, benzylamine, ethyleneimine, methylamine, ethylamine, Dimethylamine, called diethylamine.

The production of the quinones which can be used as starting material I is explained using the example of the synthesis of 2, 5-dicyano-3,6-dibromo-benzoquinone- (1,4). This connection can e.g. B. be prepared in such a way that according to Journal Organic Chemistry, 19, p. 510 (1954), to the hydroquinone and carbon dioxide 225 "C under 100 atmospheres and subsequent esterification produced 2,5 - dihydroxy- terephthalic acid diethyl ester according to the reports of the Deutsche Chemischen Gesellschaft, 21, p. 1759 (1888), described method or better in the present of aluminum chloride allows bromine to act, the resulting 2,5-dihydroxy-3,6-dibromo-terephthalic acid diethyl ester methylated by means of dimethyl sulfate, the ester groups saponified under alkaline conditions. The free Carboxyl groups are converted into acid chloride groups with thionyl chloride, these with ammonia in carboxamide groups and then by the action of thionyl chloride in cyano groups transferred, the 1,4-dimethoxy-2,5-dicyan-3,6-dibromobenzene thus obtained with a Mixture of aluminum chloride and sodium chloride demethylated at 180cd and that resulting hydroquinone derivative by the action of nitrous gases in 2.5-dicyan-3,6-di- bromo-benzoquinone- (1,4) convicted. Other 3, 6-dihalogen derivatives can be used in an analogous manner or by per se known halogen exchange processes are produced.

To prepare the cyananilic acid you can, for. B. also proceed in this way, that the above-mentioned 2,5-dihydroxy-terephthalic acid diethyl ester by means of ammonia converted into the corresponding diamide, which is alkylated at the hydroxyl groups and converts the carboxyamide groups into cyano groups in the manner described above and dealkylated. The 2,5-dicyanohydroquinone thus obtained. that also z. B. in glacial acetic acid sodium acetate can be brominated, can easily be with nitrous gases to the above-mentioned 2,5-dicyanobenzoquinone- (1,4) dehydrate.

Particularly suitable alkali metal cyanides or alkaline earth metal cyanides are sodium or potassium cyanide and calcium cyanide. The alcohols are those with 1 to 4 carbon atoms, preferably methanol and ethanol. It is convenient to use anhydrous alcohols to be used because in hydrous alcohols as a result of hydrolysis to cyananilic acid a reduction in yield occurs.

The method of the invention is expediently carried out in the way that a 2,5-dicyano-3,6-dihalogenobenzoquinone- (1,4) (l) with a Solution or suspension of an alkali or alkaline earth cyanide in an anhydrous Alcohol heated for some time, preferably at the reflux temperature of the mixture, into the resulting red solution, which contains the alkali salt of tetracyano-hydroquinone, after cooling, introduces hydrogen chloride until the color turns brown turns over, the solution evaporated to dryness and the residue with a suitable Solvents, e.g. B. diethyl ether, extracted and the solvent removed. To the The tetracyanohydroquinone can optionally be purified in a crude product sparingly soluble salt. e.g. the morpholine salt, and this by Splitting again under the action of hydrogen chloride.

But you can also proceed in such a way that one 2,5-dicyano-3,6-dihalogenobenzoquinone- (1,4) (I) first with an alcohol and then with the dialkoxy derivative obtained an alcoholic solution or suspension of an alkali or alkaline earth metal cyanide and then isolated in the manner described above.

For converting the 2,5-dicyano-3,6-dihalogenobenzoquinones into cyananilic acid it is expedient to proceed in such a way that the starting material is diluted with a aqueous inorganic base, preferably sodium hydroxide solution, heated and the cyanilic acid sets free by means of an acid. By alkylation, e.g. B. by means of a diazoalkane, one arrives at a 2,5-dicyan-3,6-dialkoxy-benzoquinone (III), which in the above is further processed in the manner described.

The production of tetracyano-hydroquinone via a 2,5-dicyano-3,6-diamino-benzoquinone derivative is advantageously carried out so that one is on a 2,5-dicyano-3,6-dihalogenobenzoquinone Let ammonia or an amine act. For this reaction has been used as a solvent Acetonitrile is particularly effective. However, the diamino derivatives can also be selected from those mentioned above Dialkoxy derivatives are obtained by reaction with amines. By exposure to Alkali or alkaline earth cyanides on these diamino derivatives in the presence of a lower one Alcohol also leads to tetracyanohydroquinone (II).

Proceeds to convert the tetracyano-hydroquinone into the quinone derivative it is expedient to take up the hydroquinone in an inert solvent and stirred with condensed nitrous gases with exclusion of moisture. As inert Solvents are suitable, for. B. carbon tetrachloride, methylene chloride and chloroform.

The yellow product is then filtered off and, if necessary by loosening, e.g. B. in methylene chloride or dichloroethane and stripping off the solvent cleaned.

The product of the process is an extraordinarily powerful oxidizing agent. It is z. B. when dissolving in alcohol, water (acidic or alkaline) or in methylene chloride solution reduced when adding tetralin, triphenylmethane or p-xylene to the hydroquinone.

The process product also has the property of having aromatic Connections, e.g. B. benzene, toluene, xylene, naphthalene, pyrene, chrysene and others, deep-colored Forming aromatic complexes.

The complex with pyrene is blue-green in solution.

It separates from methylene chloride in shiny copper crystals which do not melt when heated up to 350 ° C. As the analysis shows (calculated 76.10 0 /, C, 2.40 0 / o H; found: 76.26 0 /, C, 2.67 01o H) it is one 1: 1 complex. In the IR spectrum there is a shift in the bands towards greater wavelengths on. The product of the process can therefore be used as a reagent for or for the detection of aromatics be used.

Also in the process according to the invention as an intermediate product Occurring tetracyanoquinone forms aromatic complexes. The complex with pyrene in a ratio of 1: 1 forms red needles that do not melt when heated up to 350 C. and in the IR spectrum a slight shift in the pyrene bands towards shorter wavelengths show (analysis: calculated: 75.72 o / o C, 2.91 o / o H; found: 75.86 0 /, C 2.97 O / olH).

In addition, the tetracyano-benzoquinone- (1,4) can be used as an intermediate are used for the production of pharmaceuticals.

B e i s p i e 1 1 (synthesis route a) A. Tetracyano-hydroquinone 4 g 2,5-dicyano-3,6-dibromo-benzoquinone- (1,4) are added to a solution of 2.72 g of sodium cyanide in 200 ml of absolute methanol and refluxed for 1/2 hour. Then the resulting red solution is cooled and hydrogen chloride passed in until the color turned brown.

It is evaporated to dryness and the dry residue is extracted several times with ether. The brown, green fluorescent ether extracts are combined and converted into the mopholin salt for the purpose of purifying the tetracyano-hydroquinone. In addition one drips into the ethereal solution morpholine, whereby a red precipitate forms forms. It is filtered off with suction, washed with ether and recrystallized from absolute methanol. A second fraction of the salt is obtained from the mother liquor by adding ether.

A total of 1.05 g of morpholine salt is obtained. The free hydroquinone is obtained by dissolving the salt in as little water as possible and strong with HCI acidified. Green-yellow crystals separate out in the process. By etherifying the aqueous Solution you get some more hydroquinone. The overall yield is 0.65 g (23.70 / o the theory). The compound has no melting point.

Analysis: Calculated .... 57.150 / o C, 0.95207o H, 26.680 / o N: found .... 57.38 0 / o C, 1.03 0 / o H, 26.59 0 / o N.

The IR spectrum of the compound shows next to a broad OH band at 3175cm-1 the nitrile band (split).

Analysis of the dimorpholine salt of tetracyanohydroquinone revealed the following values: Calculated ... 56.25 0 / o C, 5.21 0 / o H: found ... 56.460 / 0 C, 5.460 / o H.

B. Tetracyano-benzoquinone- (1.4) 0.2 g of tetracyano-hydroquinone will be suspended in 12 ml of dry carbon tetrachloride and condensed with 0.5 ml nitrous gases stirred for 1 hour with exclusion of moisture. Then it is filtered off, washed with dry carbon tetrachloride and the yellow product in methylene chloride solved. It is evaporated to dryness and obtained in a practically quantitative yield a yellow, slightly brownish colored crystalline product with a melting point of 2050C (Decomposition). In addition to the nitrile and carbonyl bands, its IR spectrum also has a OH band, which was probably caused by moisture when rubbed with KBr partial reduction can be returned to the corresponding hydroquinone.

B e i s p i e 1 2 (synthesis route b) A. 2,5-Dicyan-3,6-dimethoxy-benzoquinone- (1,4) 1 g of 2,5-dicyano-3,6-dibromo-benzoquinone- (1,4) is boiled in 20 ml of absolute methanol whereby first of all a clear solution emerges from which in the heat begins to deposit a yellow powder. It is cooled and filtered, whereby 0.67 g (95 ° / c of theory) of 2,5-dicyano-3,6-dimethoxy-benzoquinone are obtained.

Analysis: Calculated .... 55.05% C. 2.760% H, 122.84% N; found .... 55.29 0 / c C, 2.73 0 / o H, 12.820 /, N.

The compound recrystallized from glacial acetic acid decomposes above from 230 "C.

Treatment with sodium hydroxide solution as in Example 2, A, gives also cyananilic acid.

B. Tetracyanohydroquinone 1.75 g 2 5-Dicyan-3,6-dimethoxy-benzoquinone- (1,4) are added to a solution of 1.75 g of sodium cyanide in 150 ml of absolute methanol and refluxed for 1/4 hour. Gradually the quinone dissolves and it is formed a clear red, red fluorescent solution. The work-up is carried out analogously to in Example 1 A given procedure. The yield is: 0.36 g (21.4% Theory). Dimethyl ether was produced as a derivative with CH2N2: green fluorescent, yellow-green needles.

Analysis: Calculated .... 60.50 o / o C, 2.52 o / o H, 23.51 o / o N; found . . 60.83 0 / o C, 2.92 0 / o H, 22.14 0 / o N.

C. Tetracyano-benzoquinone- (1,4) is obtained from the above compound prepared according to Example 1, B.

B e i s p i e l 3 (Synthesis route c) A. Cyananilic acid 1. 2,5-Dicyan-3,6-dibromo-benzoquinone- (1,4) is boiled with dilute sodium hydroxide solution until a clear solution has formed. On cooling, the sodium salt of cyananilic acid separates out in the form of yellow-brown Needles off. To clean it, it is dissolved in water, filtered and mixed with strong caustic soda. The yellow needles that are now excreted are dissolved in water. The cyanilic acid is precipitated from this solution with concentrated hydrochloric acid. This crystallizes in yellow needles, which are recrystallized from nitrobenzene can. The compound contains 2 moles of water of crystallization and shows no melting point.

Analysis: C8HpN204 2 H2O: Calculated .... 42.40 0 / o C, 2.66 0 / o H, 12.40 0 / o N; found .... 42.25 0 / o C, 3.32 0 / o H, 12.38 0 / o N.

The tetraacetyl compound obtained by reductive acetylation of cyananilic acid melts at 235 "C and gives the following analysis values: Calculated .... .. 53.40 0 / o C, 3.34 0 / o H, 7.78 0 / o N; found .... 53.61 0 / o C 3.600 /, H, 7.570 / o N.

2. 2,5-Dicyanbenzoquinone- (1,4) is suspended in dry chloroform and hydrogen chloride was passed into the suspension for 2 hours. Then filtered it is removed, the residue is dissolved in hot, dilute sodium hydroxide solution and allowed to cool. Here the sodium salt of cyanilic acid separates in the form of yellow Needles from that in the is further processed as described above.

B. 2,5-dicyano-3,6-dimethoxy-benzoquinone- (1,4) 0.2 g cyanilic acid, dissolved in a little methanol, excess diazomethane in ether is added.

The reaction is violent, and a yellow one soon separates crystalline powder.

0.1 g (44% of theory) of 2,5-dicyano-3,6-dimethoxy-benzoquinone- (1,4) are obtained, the product prepared according to Example 2, A does not have a melting point depression shows.

The further reaction takes place according to Examples 2, B and 1, B.

B e i s p i e 1 4 (synthetic route d) A. 2,5-Dicyan-3,6-dimorpholino-benzoquinone- (1,4) 150 mg of 2,5-dicyano-3,6-dimethoxy-benzoquinone are dissolved in 20 ml of anhydrous acetonitrile dissolved in the heat and added 0.5 ml of morpholine. One warms up briefly, with one dark red solution is formed, from which red needles separate when cooling. These are filtered off and washed with cold acetonitrile. Can be used for cleaning be recrystallized from glacial acetic acid. The yield is 190 mg (84.5% Theory).

Analysis: Calculated .... 58.500 / o C, 4.880 / oH, 17.080 / o N; found .... 58.29 0 / o C, 4.89 0 / o H, 17.27 0 / o N.

IR spectrum: C = N 2191 cm-1, C = O 1629 cm-1.

Melting point: 230 to 231 "C (decomposition, deflagration with evolution of gas).

Other dicyanodiaminoquinones can also be used according to the above instructions manufacture, e.g. B.

2,5-dicyano-3,6-dipiperidino-benzoquinone- (1,4): red needles.

IR spectrum: C = N 2190 cm-1, C = 0.1629 cm-1; Melting point: 190 up to 191 ° C (decomposition).

2,5-dicyano-3,6-diethylenimino-benzoquinone- (1,4): yellow needles.

IR spectrum: C N 2200 cm-1, C = 0 (weak) 1645 cm-1; Melting point: Not melted up to 300 ° C, from 2000 C gradually darkening.

2,5-Dicyan-3,6-dihexylamino-benzoquinone- (1,4): Orange needles.

IR spectrum: C = N 2185 cm-1, C = O (very weak) 1654 cm-1; Melting point: 225 to 226 ° C (partial decomposition).

The above-mentioned dicyano-diaminoquinones deliver upon exposure from Z. B. sodium hydroxide solution the sodium salt of cyananilic acid: 60 mg 2,5-dicyan-3,6-dimorpholino-benzoquinone- (1,4) are boiled with 5 ml of 2N NaOH until a clear yellow solution has formed. These is filtered and cooled, the sodium salt of cyananilic acid in long needles ruled out. It is filtered off and washed with ether. The yield is 45 mg (over 900 / o of theory).

B. Tetracyano-hydroquinone and tetracyano-benzoquinone- (1,4) By heating with sodium cyanide in methanolic solution, red fluorescent solutions are obtained of the sodium salt of tetracyano-hydroquinone, which is given in the example 1, A. Way to be worked up.

The conversion into tetracyano-benzoquinone- (1,4) takes place according to the example 1, B.

The 2,5-dicyanobenzoquinone (1,4) used as starting material in Example 3, A, 2 can be prepared in the following way: 0.5 g of 2,5-dicyanhydroquinone are in 6 cc carbon tetrachloride suspended and with 0.2 cc nitrous gases for 1 hour touched. It is filtered off with suction and the brown-yellow residue is washed with carbon tetrachloride and extract it with hot benzene.

By adding petroleum ether, the ocher-colored 2,5-dicyanobenzoquinone (1,4) the end.

The preparation of the 2,5-dicyano-3,6-dibromo-benzoquinone- (1,4) used as starting material can be done in the following way: 1. 2,5-dihydroxy-terephthalic acid was after the method given in J. Org. Chem., 19, p. 510 (1954) in a yield of 900/0 obtain.

2. 2,5-dihydroxy-terephthalic acid diethyl ester 78 g of dihydroxyterephthalic acid with 330 ml of absolute alcohol and 25 ml of alcoholic hydrochloric acid for 3 hours refluxed. Then it is evaporated to dryness, the residue is added again with 500 ml of alcohol and 30 ml of alcoholic hydrochloric acid and reflux for 3 hours. After the solvent has been distilled off, the brown residue becomes from alcohol recrystallized. 81 mg (850/0 of theory) of the above-mentioned ester are obtained, which melts at 133 "C.

3. 2.5-Dihydroxy-3,6-dibromo-terephthalic acid diethyl ester The in the Reports of the German Chemical Society, 21, p. 1759 (1888) Substance is produced according to the following method: 81 g of dihydroxyterephthalic acid diethyl ester are dissolved in 800 ml of chloroform dried over CaCl2 and 89 g of anhydrous AlCl3 added. 32.6 ml of bromine are added to the stirred suspension and the mixture is heated carefully on the water bath. The reaction soon gets going and increases too violent HBr development. The more violent the reaction, the more likely it is Bromine is consumed and the yields are so much the better. That's why you keep the approach so long in vigorous boiling until the solvent flowing back from the reflux condenser has become almost colorless. This is usually achieved after an hour. Well distilled the chloroform is removed as completely as possible (finally in a vacuum) and the red one dissolves solid residue in warm 2N NaOH, filtered and acidified. The fancy yellow one The precipitate is filtered off.

The crude product, which in a yield of 115 g (87 01o of theory) is usually still contaminated and can be cleaned in dilute sodium hydroxide solution dissolved and then precipitated again with concentrated hydrochloric acid. A an almost white product is obtained briefly when it is then dissolved in hot alcohol boiled with activated charcoal, filtered and the filtrate with about the same amount of water offset. The precipitating crystal powder has a melting point of 148 to 1520C and is Sufficiently pure for further processing.

4. 2,5-Dimethoxy-3, 6-dibromo-terephthalic acid diethyl ester 59 g of dihydroxy-dibromoterephthalic acid diethyl ester are dissolved in 325 ml of 2N NaOH and shaken with 30 ml of dimethyl sulfate for 1/2 hour. The resulting suspension is then heated to 60 ° C. for a further 1/2 hour and allowed to cool and filtered off.

The filtrate is heated to 50 ° C., 120 ml of 2N NaOH are added and the mixture is set add another 20ml of dimethyl sulfate. It is shaken again for 1/2 hour.

Heated to 60 "C for 1/2 hour, cooled and filtered.

The operation is repeated one or two more times, taking care of it care must be taken that the solution always remains alkaline.

The combined, almost white crystalline residues are mixed with water washed out and dried. The yield is 54 g (86% of theory). That Product melts at 98 "C.

5. 2,5-dimethoxy-3,6-dibromo-terephthalic acid 56 g of dimethoxy-dibromo-terephthalic acid diethyl ester are refluxed for 1 hour in a solution of 55 g of KOH in 280 ml of methanol. After a short time a clear solution forms, then the potassium salt of the resulting falls Acid off. It is evaporated to dryness, the residue is dissolved in water, filtered and acidify the filtrate with concentrated hydrochloric acid. A white crystal pulp falls at.

After suctioning off and drying, 44 g (93% of theory) are obtained of the above product, which decomposes when heated.

6.2, 5-Dimethoxy-3, 6-dibromo-terephthalic acid dichloride 44 g of dimethoxy-dibromo-terephthalic acid 440 ml of thionyl chloride are poured over them and refluxed on a water bath. After about 2 hours, a pale yellowish clear solution is formed, and the HCl development practically stops. After a total of 3 hours it is evaporated to dryness, the acid chloride remaining as a crystalline mass. It will be without cleaning further processed.

7. 2, 5-Dimethoxy-3, 6-dibromo-terephthalic acid diamide The crude, from 44 g of the corresponding acid shown acid chloride is in 450 ml dry Benzene dissolved. A moderately strong stream of NH3 is passed into this solution with cooling a. It is advisable to stir vigorously. The resulting thick paste will filtered off, freed from benzene by drying and repeated washing with Water removes the ammonium chloride. 37.7 g (86.4% of theory) remain as residue of a white, loose powder. The compound crystallizes in from nitrobenzene colorless crystals that decompose above 280cd.

Analysis: Calculated 31.40 ° / o C, 2.62 ° / o H, 7.340 / o N, 41.800 / o Br; found 31.68 ° / o C, 2.860 / o H, 7.500 / o N, 41.700 / o, Br.

8. 2,5-dimethoxy-3,6-dibromo-terephthalic acid dinitrile 9.5 g dry Dimethoxy-dibromo-terephthalic acid diamide are dissolved in 50 ml of absolute dimethylformamide solved. (The dimethylformamide is previously distilled over CaH2.) To the brown one 10 ml of double-distilled thionyl chloride are added to the solution. During the encore the mixture is cooled with ice-table salt.

The temperature should be as low as possible, preferably not above 30 ° C be. When the reaction has subsided, which can be seen from the drop in temperature, take the vessel out of the cooling mixture and leave it at room temperature stand for 1 hour. Then it is cooled again strongly and the precipitated ones are filtered off colorless crystals.

4.9 g (57.70 / o of theory) of dimethoxydibromo-terephthalic acid dinitrile are obtained. The compound recrystallized from glacial acetic acid melts at 240 ° C. and shows in the IR spectrum a nitrile gang.

9. 2,5-Dicyan-3,6-dibromo-hydroquinone To a melt of 32 g of anhydrous AlCl3 and 6.5 g of NaCl are 7 g of finely powdered dimethoxydibromoterephthalic acid dinitrile at 175 to 185 ° C admitted. The mixture is stirred and kept at this temperature for 1/2 hour. Then let it cool down, pulverize the greenish melt cake and boil it with strong hydrochloric acid. The centrifuged green-gray residue is washed with water and dry it. Yield: 5.9 g (92.50 / o of theory). The diacetyl compound melts at 218 "C.

10. 2,5-dicyano-3,6-dibromo-benzoquinone- (1,4) 12.1 g of 2,5-dicyano-3,6-dibromo-hydroquinone are suspended in 120 ml of dry carbon tetrachloride and 12 ml condensed nitrous gases added.

The mixture is left for 1 hour at room temperature under exclusion stirred by moisture and then filtered off. The resulting yellow quinone will washed with anhydrous carbon tetrachloride, dissolved in warm, dry benzene and the same volume of n-heptane is added to the solution, which has been slightly concentrated in vacuo. The precipitated yellow crystal powder is filtered off with suction and with exclusion of moisture freed from heptane. The yield of the above quinone is 9.5 g (95% the theory). It does not show a melting point, but rather slowly turns black when heated. In addition to the nitrile band, the jR spectrum shows a strong carbonyl band.

Analysis: Calculated .... 30.39 ° / o C, 8.86 ° / o N, 506 ° / o Br; found .... 29.660 / o C, 9.270 / o N, 51.20 / o Br.

Claims (1)

Claim: Process for the production of Tetracyanbenzoquinone- (1,4), characterized in that a 2,5-dicyan-3,6-dihalogenobenzoquinone- (1,4) a) at the same time a lower aliphatic alcohol and an alkali metal cyanide or alkaline earth metal cyanide or b) first a lower aliphatic alcohol and then the one thus obtained 2,5-dicyano-3,6-dialkoxy-benzoquinone- (1,4) an alkali cyanide or alkaline earth cyanide allowed to act or that c) first a 2,5-dicyano-3,6-dihalogenobenzoquinone- (1,4) or by the action of hydrogen halide on 2,5-dicyano-benzoquinone- (1,4) reaction product obtained hydrolyzed to cyananilic acid, this in a known manner to a 2,5-dicyan-3, 6-dialkoxy-ben zochinon- (1,4) dialkylated and then a Alkali metal cyanide or alkaline earth metal cyanide is allowed to act or d) a 2,5 - dicyanide - 3,6 - dihalogen - benzoquinone- (1,4) or one of it by the action of a lower one aliphatic alcohol obtained according to b) 2,5-dicyano-3,6-dialkoxy-benzoquinone- (1,4) by treating with ammonia, a primary or secondary amine into a corresponding one 2,5-dicyan-3,6-diamine benzoquinone derivative converted and then an alkali metal cyanide or alkaline earth cyanide act in the presence of a lower aliphatic alcohol leaves and the tetracyano-hydroquinone thus obtained by treatment with nitrous gases converted into tetracyano-benzoquinone- (1,4).