A method for the preparation of mixtures of alkali metal salts of organometallic, aromatic carboxylic acids and alkali metal salts of the corresponding dimeric aromatic carboxylic acids

摘要

A Group Ia metal is heated in an inert atmosphere with an aromatic carboxylic acid or with a Group Ia- or IIa-metal salt thereof to give a mixture comprising a nuclear Group Ia-metal substituted Group Ia or IIa metal salt of an aromatic carboxylic acid and a Group Ia or IIa metal salt of an aromatic carboxylic acid dimer. Specifically, using sodium and sodium benzoate (or benzoic acid) the product comprises a mixture of sodium p-sodio-benzoate and the sodium salt of diphenyl-p,p1-dicarboxylic acid. Higher temperatures favour the production of the salt of the dimerized acid, particularly when the reaction is carried out in a liquid medium whereas lower temperatures favour the production of the metallo-substituted salt. Using less than 0.2 equivalent of alkali metal per equivalent of carboxylic acid salt at temperatures between 250 DEG and 300 DEG C., the salt of the dimerized acid is preferably formed, but using two equivalents of alkali metal per equivalent of carboxylic acid salt at 100-200 DEG C. favours the production of the metallo substituted salt. Between 0.2 and 1 equivalent mixtures without a predominating compound are produced. The reaction may be carried out while grinding the reactants in a ball-mill under an inert atmosphere, e.g. argon, krypton or nitrogen. If desired, an inert liquid blanket such as mineral oil or other cheap high boiling paraffinic hydrocarbon or an inert ether such as diethylene glycol dimethyl ether, diethylene glycol diethyl ether or tetrahydrofuran may be employed. Solvents are not usually used for the reaction. The reactant particles should preferably be of size less than 10 microns. Carbonation of the sodium p-sodiobenzoate yields disodium terephthalate, from which terephthalic acid may be obtained by hydrolysis. Example IV describes the metalation of sodium naphthoate to give sodium sodio naphthoate and its carbonation to give dicarboxy naphthalene. Example V describes the preparation of disodium sodio-isophthalate and its carbonation to tricarboxy benzene.