METHOD OF OBTAINING METHYL 5-METHOXY-2-SULPHOAMOYLBENZOATE Russian patent published in 2015 - IPC C07C311/15 C07C307/02 

FIELD: chemistry.

SUBSTANCE: invention relates to a method of obtaining methyl 5-methoxy-2-sulphoamoylbenzoate, which is a multi-stage method, including the stage of amidation and the stage of crystallisation, characterised by the fact that at the first stage etherification of 3-methoxybenzoic acid with methanol is carried out in a medium of an organic solvent in the presence of a catalyst - sulphuric acid, after which the obtained mixture is boiled for 10-11 hours, then washed from sulphuric acid, the solvent is distilled, the obtained methyl ether of 3-methoxybenzoic acid at the second stage is introduced into the sulphochlorination reaction at a temperature of 55-60°C with the fourfold excess of chlorosulphonic acid, the process is carried out for 2.5-3 hours, the obtained methyl 2-(chlorosulphonyl)-5-methoxybenzoate is extracted by pouring out of the reaction mass on ice, at the third stage of amidation it is introduced into a reaction with the twofold excess of ammonia in a medium of an organic water-soluble solvent (for instance, ancetonitrile or dioxane) at room temperature, after which the obtained methyl 5-methoxy-2-sulphoamoylbenzoate is sedimented and crystallised by the known method.

EFFECT: method of obtaining methyl 5-methoxy-2-sulphoamoylbenzoate, characterised by the fact that it includes the lower number of stages, the absence of the oxidation stage, the reduction of the sewage amount, has been elaborated.