The formation of 1-dimethylaminonaphthalene-5-sulphonamide during the preparation of 1-dimethylaminonaphthalene-5-sulphonylamino acids.

1. The amount of 1-dimethylaminonaphthalene-5-sulphonamide formed during the reaction of an amino acid with 1-dimethylaminonaphthalene-5-sulphonyl chloride depends on the structure of the amino acid and on the conditions used. 2. The reaction probably involves attack of a further molecule of 1-dimethylaminonaphthalene-5-sulphonyl chloride on the 1-dimethylaminonaphthalene-5-sulphonyl-amino acid and also gives the aldehyde (or ketone) with one carbon atom less than the parent amino acid.