Patent GB-405846-A (GB)
Title: Improved method of preparing salts of aliphatic acids
IPC: C07C51/41
Filed: 1933-05-03
Abstract: Alkali salts of aliphatic carboxylic acids are obtained by adding saturated primary or secondary monohydric aliphatic alcohols containing at least two carbon atoms to fused alkali hydroxides maintained at 250--325 DEG  C.  The pressure is preferably atmospheric, but may be higher or lower.  A primary alcohol of the formula RCH2OH, where R is an alkyl group, yields an alkali salt of the acid RCOOH and hydrogen; a secondary alcohol of the formula RCHOHR<1>, where R<1> is an alkyl group containing the same number of carbon atoms as R or a lower number, yields an alkali salt of the acid RCOOH, the hydrocarbon R<1>H, and hydrogen.  Preferably, a mixture of sodium and potassium hydroxides is used containing between 0.5 and 3 mols. of sodium hydroxide per mol. of potassium hydroxide; a little water may also be present, either in the hydroxide or in the alcohol.  When ethyl alcohol or a mixture containing it is treated, the initial alkali hydroxide mixture preferably contains sodium and potassium acetates in such proportion that the ratio Na : K in the mixture lies between 0.5 and 3, and at least 1 mol. of acetate is present for each 9 mols. of hydroxide.  Examples are given of the treatment of n-propyl alcohol, isobutyl alcohol, ethyl alcohol, isopropyl alcohol, and a mixture of n-propyl and sec.-butyl alcohols. Reference is made also to the treatment of higher aliphatic alcohols such as nonanol-2, cetyl alcohol, and a mixture containing heptanol-1 and octanol-2.ALSO:Alkali salts of aliphatic carboxylic acids are obtained by adding saturated primary or secondary monohydric aliphatic alcohols containing at least two carbon atoms to fused alkali hydroxides maintained at a temperature between about 250 and 325 DEG  C.  The reaction is preferably effected under atmospheric pressure, but higher or lower pressures may be applied.  A primary alcohol of the formula RCH2OH, where R is an alkyl group, yields an alkali salt of the acid RCOOH and hydrogen; a secondary alcohol of the formula RCHOHR<1>, where R<1> is an alkyl group containing the same number of carbon atoms as R or a lower number, yields an alkali salt of the acid RCOOH, the hydrocarbon R<1>H, and hydrogen.  The process may thus be used to prepare a single acid or a lower number of acids from a mixture of alcohols, such as may be obtained from cracking gases or from chlorinated petroleum hydrocarbons; any tertiary alcohols in such mixtures are unaffected, and may be recovered.  When a mixture of a primary and a secondary alcohol is treated, the primary alcohol reacts more rapidly than the secondary alcohol, and a part of the latter can be recovered if the process is not carried to completion.  Preferably, a mixture of sodium and potassium hydroxides is used containing between 0.5 and 3 mols. of sodium hydroxide per mol. of potassium hydroxide; a little water may also be present, either in the hydroxide or in the alcohol.  When ethyl alcohol or a mixture containing it is treated, the initial alkali hydroxide mixture preferably contains sodium and potassium acetates in such proportion that the ratio Na : K in the mixture lies between 0.5 and 3, and at least 1 mol. of acetate is present for each 9 mols. of hydroxide.  The reaction product may be worked up by dissolving it in caustic soda, crystallizing the sodium carboxylate from the solution, and evaporating the mother liquor for reuse. Alternatively, the reaction product may be neutralized with an aqueous solution of the acid corresponding to the alcohol treated, and then dried and treated with sulphuric or gaseous hydrochloric acid to recover the free carboxylic acid.  Examples are given in which: (1) alkali propionate is obtained from n-propyl alcohol (2) alkali isobutyrate is obtained from isobutyl alcohol; (3) alkali acetate is obtained from ethyl alcohol; (4) alkali acetate is obtained from isopropyl alcohol; (5) alkali propionate is obtained from a mixture of n-propyl and sec.-butyl alcohols; in each example, the alcohol is added to a fused mixture of sodium and potassium hydroxides maintained at 285--295 DEG  C., and in example 3 sodium acetate is added to the hydroxide mixture. Reference is made also to the treatment of higher aliphatic alcohols such as nonanol-2, cetyl alcohol, and a mixture containing heptanol-1 and octanol-2.