GB1337763A - Electrolytic condensation of carboxylic acids - Google Patents

Abstract

1337763 Electrochemical condensation of carboxylic acids BADISCHE ANILIN- & SODAFABRIK AG 19 April 1971 [28 March 1970] 25345/71 Heading C2C [Also in Division C7] In a process for the electrochemical condensation of carboxylic acids at a degree of neutralization of the acid of less than 20% molar, preferably less than 10% and a current density of more than 10 A/dm.<SP>2</SP>, preferably from 15 to 40 A/dm.<SP>2</SP> in a solvent using electrodes which are impermeable to liquids, the distance between the electrodes is from 0À1 to 2 mm., preferably 0À3 to 0À8 mm. and the electrolyte is caused to flow through the space between the electrodes at a rate of from 0À05 to 2 m./sec., preferably 0À1 to 0À7 m./sec. The preferred solvent for the electrolyte is methanol although water, lower alcohols or N,N-dialkylamides of lower alkanoic acids or mixtures thereof may be employed. The degree of neutralization of the carboxylic acid used may be adjusted using anhydrous sodium carbonate, sodium or potassium methylate or ethylate, potassium carbonate, triethylamine, dimethyl aminoethanol or morpholine. The electrodes have smooth surfaces and the anodes are preferably of platinum, platinumrhodium, platinum-iridium, gold or goldplatinum applied as a thin layer to a conducting substrate, e.g. aluminium refined steel, titanium or graphite. The cathode may be stainless steel or nickel. The process may be carried out batchwise or continuously. In the latter case an electrolytic cell having a plurality of plane plate-shaped electrodes in a bipolar series arrangement may be used. The distance between the electrodes may be defined by insulator strips and the length of the gap through which the reaction mixture flows is preferably between 5 and 100 cm. Temperature is maintained between 20‹ and 60‹ C. The process is described as being of interest in the synthesis of di-functional compounds from substituted alkanoic acids other than α-substituted acids, i.e. acids having substituents in the # or a more remote position. Such substituents may be ester, acylamino, acyloxy, nitrilo, halo, aryl, alkyl, aralkyl or heterocyclic groups. Particular examples of the use of the invention are the synthesis of sebacic acid ester from adipic acid half ester, of suberic acid ester from glutaric acid half ester, of thapsic acid ester from azaleic acid half ester, of 2,2<SP>1</SP>,5,5<SP>1</SP>-tetramethyl adipic acid ester from 2,21-dimethyl succinic acid half ester, of N,N<SP>1</SP>- diacetyl-dimethylene diamine from #-acetylaminocaproic acid, of 1,8-octanediol diformate 5-formyloxyvaleric acid, of decamethylene dicyanide from #-cyanocaproic acid of 1,20- dibromoicosane from 11-bromo undecanoic acid and of 1,10-dichlorodecane from #-chlorocaproic acid.