Abstract

The present invention relates to a method for preparing MHB (methyl-4-hydroxyiminobenzoate) from by-products generated in a process for preparing DMT (dimethyl terephthalate). The method comprises: (a) adding alcohol to reaction by-products containing methyl formylbenzoate and filtering the resultant, wherein the by-products are generated in a process for preparing DMT; (b) converting the methyl formylbenzoate within a filtrate into methyl 4-hydroxyiminobenzoate through an oximation reaction by adding (i) hydroxylamine or inorganic acid salts of hydroxylamine and (ii) alkali components to the filtrate after filtration; and (c) purifying the converted methyl 4-hydroxyiminobenzoate.

IPC Classes  ?

• C07C 249/08 - Preparation of compounds containing nitrogen atoms doubly-bound to a carbon skeleton of oximes by reaction of hydroxylamines with carbonyl compounds
• C07C 249/14 - SeparationPurificationStabilisationUse of additives
• C07C 251/68 - Oximes having oxygen atoms of oxyimino groups esterified by carboxylic acids with at least one of the esterifying carboxyl groups bound to a carbon atom of a six-membered aromatic ring

Abstract

The present invention relates to a preparation method of 4-aminomethylbenzoic acid comprising the following steps: preparing 4-carboxylbenzaldehyde or an alkyl ester thereof (methyl 4-formyl benzoate); reacting the 4-carboxylbenzaldehyde or an alkyl ester thereof (methyl 4-formyl benzoate) with hydroxyamine to oximate the same; and contact reducing 4-carboxylbenzaldehyde oxime or an alkyl ester oxime thereof obtained by the oximation, through hydrogen in a sodium hydroxide aqueous solution. Since methyl 4-hydroxyaminomethyl benzoate is reacted as a raw material in the presence of an alkali, hydrogen of a relatively low pressure can be used and a purification process is also simple, thereby enabling preparation of 4-aminomethylbenzoic acid with a low cost and high yield.

IPC Classes  ?

• C07C 227/12 - Formation of amino and carboxyl groups
• C07C 229/38 - Compounds containing amino and carboxyl groups bound to the same carbon skeleton having amino groups bound to acyclic carbon atoms and carboxyl groups bound to carbon atoms of six-membered aromatic rings of the same carbon skeleton
• B01J 23/40 - Catalysts comprising metals or metal oxides or hydroxides, not provided for in group of noble metals of the platinum group metals
• B01J 23/755 - Nickel