DE1944279A1 - Process for the production of octadienes and decatrienes - Google Patents

Description

Our reference: O.Z. 26 340 Bk / GP 67OO Ludwigshafen, August 29, 1969

Process for the production of octadienes and dodecatrienes

The invention relates to a process for the production of octadienes and dodecatrienes by electrolysis of butadienes.

From Chemical Reviews Volume 68, 1968, page 471 it is known that by electrolysis of 1,4-diphenylbutadiene in the presence of methanol and potassium hydroxide and platinum electrodes, trans-1,4-dimethoxy-1,4-diphenyl-2-butene receives. It was therefore not to be expected that dimerization would occur in the electrolysis of butadienes entry.

It has now been found that octadienes and dodecatrienes can be obtained by electrolysis of butadienes in the presence of lower aliphatic Alcohols and a conductive salt are advantageously obtained if graphite electrodes are used for the electrolysis.

Thanks to the new process, a large number of octadienes and dodecatrienes, which were previously difficult to access, are easily accessible accessible.

Preferred butadienes can have 1 to 2 phenyl radicals, in particular by 1 to 2 alkyl radicals with 1 to 4 carbon atoms be substituted. Butadiene itself is of particular importance. Suitable starting materials are, for example, 1,4-diphenylbutadiene, Isoprene or butadiene.

The electrolysis is carried out in the presence of lower aliphatic alcohols, in particular alkanols with 1 to 3 carbon atoms carried out. Methanol has proven particularly useful. It is advantageous to use 1 to 3 moles of alcohol per mole of butadiene.

Electrolysis is used to improve conductivity Conductive salts are also used. It is advantageous to use the electrolyte salts

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Alkali _t iodides, alkali perchlorates or alkali methylates or mixtures thereof. Sodium iodide, sodium lumperehlorate or sodium methylate have proven particularly useful as conductive salts. Is advantageous to use as much electrolyte salt that its concentration $> is electrolyzed in the mixture to 1 to 10 wt., In particular 2 to 8 wt.%.

The electrolysis is advantageously carried out at temperatures from -40 to + 40 ° G, in particular from -30 to -f -10 ° C at an anode voltage of + 0 * 5 to 2.0 V (measured against a silver / silver chloride electrode), in particular 0 ₉ S to 1.8 and current densities from 25 to 75 mA / cm.

An essential feature of the invention is that the electrolysis is carried out on graphite electrodes. In general, those which are commercially available are used which are suitable for electrolysis purposes Graphite electrodes. Graphite electrodes have proven particularly useful P-127 from Slgri, Meitingen near Augsburg.

The method according to the invention is carried out, for example, by adding a mixture of the butadienes described nnu in a suitable electrolysis vessel equipped with graphite electrodes at a distance of, for example, 10 mm. Alcohols in the specified ratio and the amounts of conductive salt described are presented and the electrolysis is carried out under the specified conditions. The mixture to be electrolyzed is advantageously circulated during the electrolysis in order to achieve a good mixture. It is possible to carry out the electrolysis with or without a diaphragm; it is advantageous to carry out the electrolysis without a diaphragm. In general, the electrode is carried out until a consumption of 0.1 to 0.5 Faraday is reached. After the electrolyte salt has been deposited, the mixture is worked up by known methods, for example distillation.

The octadienes made by the process of the invention and dodeeatrienes are suitable for the production of conjugated polyenm e.g. by splitting off methanol by treating with Polyphosphoric acid.

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6AD ORiGiNAL

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example

A solution of 8 g of sodium perehlorate in 60 g of butadiene and 120 ml of methanol is obtained at −16 ° C. and an anode voltage of +1.7 V.

with a current density of 30 mA / cm on graphite electrodes P 127 (from Sigri, Meitingen) electrolyzed to a consumption of 0.38 Faraday. Then the methanol distilled off and the residue mixed with 20 ml of water. Then it is extracted with ether and the ether extract fractionally distilled after distilling off the ether. 2 fractions are obtained

a) Boiling point 85 to 100 ° C at 14 mm Hg (14 g)

b) Boiling point 95 to 105 ° C at 0.01 mm Hg (7 g)

The fraction a) is to gaschromatographiseher analysis to 1/3 each from t ^rans i ^t rans-l, 8-Dimethoxyoctadien-2,6, 3,6-Dimethoxyoctadien-l, 7, and trans-l, 6-dimethoxy-2 & etadien, 7th According to gas chromatographic analysis, fraction b) consists essentially of trans-1,2-dimethoxydodecatriene-2,5 * 9 and 1,1-dimethoxydodecatriene-2,6,11.

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Claims (1)

O.Z. 26th Claim Process for the production of octadienes and dodecatrienes by electrolysis of butadienes in the presence of lower aliphatic alcohols and a conductive salt, characterized in that graphite electrodes are used for the electrolysis. Badische Anilin- & Soda-Fabrik AG 109810/2220 COPY