GB898780A - 3-diacetamido-2,4,6-triiodobenzoic acid and derivatives thereof - Google Patents

Abstract

The invention comprises compounds of the general formula <FORM:0898780/IV (b)/1> where R represents a hydrogen atom, an alkyl1 group containing from 1 to 6 carbon atoms, an alkali or alkaline earth metal or an ammonium ion in which the valencies of the nitrogen are satisfied at least in part by hydrogen, any remaining valencies being satisfied by alkyl or hydroxyalkyl groups containing not more than 6 carbon atoms which are suitable for use in X-ray contrast media (see Group VI). Compounds of the above formula in which R represents a hydrogen atom or an alkyl group containing from 1 to 6 carbon atoms may be obtained by acetylating the corresponding amine or mono-acetylated amide. The esters of the invention may be obtained by esterification of the free, acid e.g. by converting the latter to an alkali metal salt and reacting the latter with an appropriate alkyl sulphonic ester or sulphate, e.g. n-propyl toluenep-sulphonate or diethyl sulphate. The acetylation may be carried out with acetic anhydride in the presence of sulphuric acid or acetyl chloride in the presence of dimethyl aniline or pyridine. The examples relate to the preparation of methyl ethyl, n-propyl, n-butyl and n-amyl esters and sodium diethanolamine salts of 3-diacetamido2,4,6-triiodobenzoic acid. Ethyl 3-acetamido-2,4,6,-triiodobenzoate for use as starting material is obtained by treating the corresponding sodium salt with diethyl sulphate. The methyl ester is prepared similarly. n-Propyl, n-butyl and n-amyl 3-acetamido2,4,6,-triiodobenzoate for use as starting materials are obtained by reacting the appropriate alkyl toluene p-sulphonate with sodium 3-acetamido 2,4,6-triiodobenzoate.ALSO:An X-ray contrast medium comprises a compound of the general formula <FORM:0898780/VI/1> where R represents a hydrogen atom, an alkyl group containing from 1 to 6 carbon atoms, an alkali or alkaline earth metal or an ammonium ion in which the valencies of the nitrogen are satisfied at least in part by hydrogen, any remaining valencies being satisfied by alkyl or hydroxyalkyl groups containing not more than 6 carbon atoms in association with a pharmacologically acceptable diluent (see Group IV (b)). The alkyl esters may be used in the form of a suspension in oil, such as arachis oil, or in water. The salts may be used in aqueous solutions. In examples the preparations of an arachis oil suspension of n-propyl 3-diacetamido-2: 4 : 6-triiodobenzoate and an aqueous solution of the diethanolamine salt of 3-diacetamido-2: 4 : 6-triiodobenzoic acid are described.