PREPARATION OF POLYVINYLAMINE FROM POLYACRYLAMIDE - A REINVESTIGATIONOF THE HOFMANN REACTION

The Hofmann modification of polyacrylamide to yield vinylamine homo- o r copolymers was reinvestigated in order to determine the real scope o f a procedure of great potential interest in polymer chemistry. The co nditions of the treatment by sodium hypochlorite followed by concentra ted sodium hydroxide at low temperature (0-degrees-C) were adjusted to avoid or to limit side-reactions between pendant reactive groups. A b road range of initial mole ratio alpha of sodium hypochlorite per init ial amide function (0,05 < alpha < 1, 10) was explored. The reported p rocedure allows to prepare in excellent yield water-soluble polymers o f controlled vinylamine content. The presence of carboxylic acid funct ions (2 - 10 mol-%) on the main chain, observed with low values of alp ha, or of urea functions (1 - 5 mol-%) observed with the highest value s of alpha, was evidenced on the basis of analytic and spectroscopic m easurements. Simple mechanistic considerations allow to propose ration al schemes accounting for the side-reactions leading to the detected m inor functionalities.