| 摘要 |
Alkali metal aromatic hydroxy carboxylates or mixtures thereof are prepared by reacting an alkali metal phenoxide, dissolved or dispersed in a neutral or basic organic solvent, which solvent is a hydrocarbon, ketone, ether, amine or heterocyclic compound, with carbon dioxide under substantially anhydrous conditions, in the presence of an added amount of neutral aromatic hydroxy carboxylate. By "neutral" aromatic hydroxy carboxylate is meant a salt of the acid in which the acidic hydrogens of all the hydroxy and carboxyl groups in the molecule have been replaced by alkali metal. The phenols whose alkali metal phenoxides may be used as starting materials may be mono- or polynuclear and substituted by ether groups or carboxylic or sulphonic acid groups. Specified phenols are phenol, cresols, alkyl phenols, halophenols, nitrophenols, aminophenols, naphthols, 5 : 6 : 7 : 8-tetrahydro-2-naphthol, halonaphthols, nitronaphthols, aminonaphthols, 2-and 4-hydroxydiphenyl, anthrols, p-benzylphenol, catechol, hydroquinone and 1 : 2- and 1 : 5-dihydroxynaphthalene. The neutral aromatic hydroxy carboxylate added in the process is usually, but not essentially, derived from the same phenol as is used in the process. The anhydrous mixture of alkali metal phenoxide and neutral aromatic hydroxy carboxylate is prepared by mixing the phenol and aromatic hydroxy carboxylic acid possibly in the form of their alkali metal compounds, and then if necessary completing the replacement of any remaining acidic hydrogen atoms in the mixture by reaction with alkali metal, alkali metal hydroxide or alkali metal alkoxide, followed by removal of any water or alcohol formed. For the free phenol, 105 per cent of the theoretical amount of alkali required is added. For the free aromatic hydroxy carboxylic acid, from 90 to 200 per cent of the theoretical amount of alkali, is added. The preferred solvents for the reaction are aromatic hydrocarbons such as toluene, xylenes, ethyl benzene and cumenes. Temperatures of from 100 DEG to 300 DEG C. and pressures from atmospheric up to about 2000 pounds per square inch guage may be employed. Under these conditions about 3 to 5 hours are required for reaction. The phenols used in the examples were mixtures of alkyl phenols obtained by alkylating phenol with olefines containing 14-18 carbon atoms. In examples (1) the effect of varying amounts of sodium hydroxide relative to the added alkali metal aromatic hydroxy carboxylate on the acid value of the carboxylated product, and hence on the degree of conversion of phenoxide to hydroxy carboxylate, was determined; (2) and (3) the effect of varying amounts of added neutral alkali metal aromatic hydroxy carboxylate on the acid value of the carboxylate was determined; (4) the process of the invention was modified by rephenating and recarboxylating the initial carboxylation product by the method of Specification 734,598. |
