Patent GB-734605-A (GB)
Title: Improvements in or relating to the preparation of alkali metal phenates and solutions thereof
Inventor: HARTLEY JAMES
IPC: C07C39/235
Filed: 1952-11-19
Abstract: A process for preparing solutions of alkali metal phenates suitable for subsequent reaction with carbon dioxide to produce aromatic hydroxy carboxylates comprises mixing a phenol with a solution of an alkali metal hydroxide in an alcohol containing from 1 to 4 carbon atoms in the molecule, distilling off a major proportion of the alcohol, adding a neutral or basic organic solvent for the alkali metal phenate, which solvent boils at a higher temperature than the alcohol and is a hydrocarbon, ketone, ether amine, or heterocyclic compound, and distilling off residual alcohol and water with part of said solvent to leave as a residue a substantially anhydrous solution of the alkali metal phenate in the solvent.  The phenols may contain such nuclear substituents as hydrocarbon radicals, halogen atoms and amino, nitro, carboxylic acid or sulphonic acid groups.  Mentioned are phenol, o-, m- and p-cresols, alkyl-phenols obtained by alkylating phenols with one or more alcohols, alkyl halides, ethers or olefins respectively, particularly mono- or di-alkyl phenols obtained by alkylating phenols with olefins containing from 8 to 18 carbon atoms in the molecule obtained by cracking petroleum fractions, halogen-substituted phenols, nitrophenols, aminophenols, 1- or p  2-naphthol, 5 : 6 : 7 : 8-tetrahydro - 2 - naphthol, halogen-, nitro-, or amino-naphthols, 2- and 4-hydroxydiphenyls, p-benzylphenol 1- and 2-anthrols, 1 : 2- and 1 : 4-dihydroxybenzenes, and 1 : 2- and 1 : 5-dihydroxynaphthalenes. Methanol, ethanol, n-propanol and n-butanol are the preferred alcohols, isopropanol also being mentioned.  Recovered alcohol from a later stage, containing up to about 5 per cent of water and 10 per cent of the neutral or basic solvent may be used.  The alkali may be used as a concentrated aqueous solution.  The removal of alcohol may be commenced during the addition to the alkali metal hydroxide of the phenol, which may be preheated to about 100 DEG  C.  Preferably 85 to 90 per cent of the alcohol is removed in the first distillation.  The neutral or basic solvent preferably has a boiling-point at least 30 DEG  C. above that of the alcohol used, and is immiscible with water and with alcohols having 1 to 4 carbon atoms in the molecule.  Specified are hydrocarbons: benzene, toluene, xylenes, ethyl benzene, cumene, heptane, octane, decane, kerosene, gas oil, cyclohexane, methylcyclohexane and tetrahydronaphthalene; ketones: methyl ethyl ketone, methyl amyl ketone, methyl isobutyl ketone, ethyl n-butyl ketone, diethyl ketone, di-isopropyl ketone, di-isobutyl ketone, di-sec.-butyl ketone, 2-octanone, di-n-butyl ketone, butyl n-hexyl ketone, pinacolone, cyclopentanone and acetophenone; ethers: diisobutyl, ethyl amyl, ethyl n-butyl, ethyl n-hexyl, and ethyl n-heptyl ethers, 1 : 3- and 1 : 4-dioxanes, 1 : 4-dioxene, 2-methyl-1 : 3-dioxane, anisole and phenetole; basic solvents: n-heptylamine, 2-amino-n-heptane, n-amylamine, dipropylamine, triethylamine, tripropylamine, aniline, dimethylaniline, cyclohexylamine, pyridine, piperidine, picolines, lutidines, collidines and quinoline.  In an example: (1) a 3-pentadecenyl phenol obtained from cashew nutshell oil is added to a solution of sodium hydroxide in butanol.  After distilling off the major part of the butanol, the distillation is continued with the continuous addition of xylene at the same rate as the distillate comes out, until the vapour has the boiling-point of xylene.  In similar examples the corresponding sodium phenate is prepared from (2) to (4) an alkyl phenol obtained by alkylating phenol with a mixture of olefins containing 10 to 18 carbon atoms in the molecule in the presence of a zinc chloride/hydrogen chloride catalyst; (5) and (6) p-tertiary octyl phenol.  In (6) methyl iso-butyl ketone is used as solvent.  As alcohols are mentioned ethanol, industrial methylated spirits, methanol and n-butanol.  The solutions of phenates obtained in examples 1, 2, 3 and 6 are reacted at 130 DEG  to 140 DEG  C. with carbon dioxide under pressure to give the corresponding alkyl salicylic acids.  Specification 734,598 is referred to.