Patent GB-975772-A (GB)
Title: Metallometallic salts of aromatic mono carboxylic acids and process for their preparation
IPC: C07F3/00
Filed: 1961-03-17
Abstract: Metallic salts of a -metallo aromatic monocarboxylic acids of formula <FORM:0975772/C1/1> where R1 and R2 are hydrogen or an alkyl, alkenyl or aryl substituent, M and M1 are alkali metals or alkaline earth metals, a is from 1 to 5 and y is the valency of M are made by reacting an amide or hydride of an alkali metal or an alkaline earth metal or the free alkali metal or alkaline earth metal with an alkyl substituted benzoic acid or an alkali or alkaline earth metal salt of said acid, said acid containing at least one a -hydrogen atom on an alkyl group.  The invention also includes as new compounds sodium a -sodio-p-toluate and sodium a -sodio-o-toluate. The alkyl-substituted benzoic acids may be prepared by oxidizing the corresponding alkyl-substituted aromatic hydrocarbon.  The reaction may be carried out at a temperature between 70 DEG  and 225 degrees, preferably by grinding in a ball-mill in an inert atmosphere such as nitrogen or under an inert liquid blanket.  When a metal amide is used in the reaction it may be a metal derivative of an organic amide e.g. N-sodium-n-propylamide, prepared by reacting n-propylamine with finely divided sodium.  The aromatic acid may carry on the ring other substituents inert to the metallating agent.  It may also be a condensed ring system such as naphthalene or anthracene or a fused ring system of formula <FORM:0975772/C1/2> where R is the same as R1 and R2 defined above, a has a value of 1 to 3 and x is 1 to 5.  When using isomeric mixtures the meta-isomer is destroyed giving only the ortho- and para-products.  Aromatic dicarboxylic acids may be obtained by carbonation of the metallic salts of the a -metallo aromatic carboxylic acids with CO2 or a carbonate.  Thus sodium a -sodio-p-toluate may be carbonated to give homoterephthalic acid, and sodium a -sodio-o-toluate gives homophthalic acid. Symmetrical aromatic dibasic acids may be produced by reaction with halogens, <FORM:0975772/C1/3> preferably by passing the halogen gas into a solution of the metallic a -metallo salt in an inert solvent at a temperature between 0 DEG -100 DEG C. Hydroxy acids and mercapto acids may be produced by reaction with oxygen <FORM:0975772/C1/4> or sulphur respectively <FORM:0975772/C1/5> An inert e.g. hydrocarbon or ether, solvent may be used. When reacting with sulphur the solvent chosen should provide mild oxidizing conditions. Using a solvent which has a high solubility for sulphur and vigorous oxidizing conditions an acid containing a disulphide link is obtained. Reaction with an organic halide produces a salt of a longer chain substituted aromatic monocarboxylic acid: excess organic halide (1.75:1 to 2.50:1) yields an ester of the longer chain monocarboxylic acid. Reaction with lactones gives omega (carboxy aromatic) aliphatic acids e.g. Example III describes the preparation of gamma (p-carboxy phenyl) butyric acid from sodium a -sodio-p-toluate and propiolactone in tetrahydrofuran. Other suitable solvents specified include hydrocarbons, dimethyl carbitol, and ethylene glycol dimethyl ether. Similar reactions occur with ethylene oxide or styrene oxide: e.g. sodium a -sodio-o-toluate and ethylene oxide yield the sodium salt of gamma (o-carboxyphenyl) sodium propoxide.  The salts of the invention may be alkylated with olefines e.g. sodium a -sodio-p-toluate and ethylene yield the sodium salt of p-alpha-ethyl toluic acid. Epichlorhydrin at a temperature between 50 and 150 DEG C. yields a polyether containing some ester linkages.  The salts of the invention may be reacted with aldehydes or ketones instead of epichlorhydrin in an analogous manner.  Reaction with sulphur monochloride yields a disulphide.