Preparation of polyvinylamine from polyacrylamide: a reinvestigation of the hofmann reaction

Abstract

Abstract The Hofmann modification of polyacrylamide to yield vinylamine homo‐ or copolymers was reinvestigated in order to determine the real scope of a procedure of great potential interest in polymer chemistry. The conditions of the treatment by sodium hypochlorite followed by concentrated sodium hydroxide at low temperature (0°C) were adjusted to avoid or to limit side‐reactions between pendant reactive groups. A broad range of initial mole ratio a of sodium hypochlorite per initial amide function (0,05 < a < 1,10) was explored. The reported procedure allows to prepare in excellent yield water‐soluble polymers of controlled vinylamine content. The presence of carboxylic acid function (2 – 10 mol‐%) on the main chain, observed with low values of a , or of urea functions (1 – 5 mol‐%) observed with the highest values of a , was evidenced on the basis of analytic and spectroscopic measurements. Simple mechanistic consideration allow to propose rational schemes accounting for the side‐reactions leading to the detected minor functionalities.