Council of Scientific and Industrial Research

Rajan Hiralal Naik

Srinivasachari Rajappa

Abdul R Deshmukh

Sagun Kashinath Tandel

Padmakar Laxman Joshi

Gurunath H Kulkarni

The present invention provides an improved method for the preparation of dipyrromethanes by reacting the pyrrole with an aldehyde in the presence of an cation exchange resin.

Process for the synthesis of dipyrromethanes

A process for the preparation of an S-alkyl ester of an N-alkyl carbamothioic acid having the formula: ##STR1## wherein R and R.sub.2 are each an alkyl group and R.sub.1 is hydrogen or alkyl, which includes refluxing the corresponding alkyl ester of N-alkyl thiocarbamio acid having the formula I ##STR2## wherein R and R.sub.2 are each alkyl and R.sub.1 is hydrogen or alkyl, in the presence of an acid catalyst selected from the group consisting of iodine and sulfuric acid.

Pesticidal ester preparation

A process for the preparation of alkyl esters of N-alkyl or N-aryl thiocarbamic acid having the formula: ##STR1## wherein R is alkyl or aryl, R.sub.2 is alkyl and R.sub.1 is hydrogen or alkyl which comprises reacting the S-alkyl ester of N-alkyl or aryl dithiocarbamic acid having the formula: ##STR2## wherein R, R.sub.1, R.sub.2 have the meanings stated above with an appropriate alkali metal alkoxide in the presence of one or more alcoholic solvents.

Process for making alkyl N-alkyl or N-aryl-thiocarbamates

The invention relates to a process for the preparation of aryl esters of N-alkyl carbamic acids. The process comprises reacting an alkyl N-alkyl carbamate of the general formula:

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Rajan Hiralal Naik