Studies in ring-chain polymerisation

Abstract

The synthesis of anhydrosulphite and anhydrocarboxy
derivatives of α-hydroxy acids has been examined together
with the decomposition of these compounds by routes which
lead to α-polyester formation.

The products obtained from the direct reaction of
thionyl chloride and several members of the α-hydroxy
acid series have been isolated and identified. Possible
reaction routes are discussed, together with the effect
of α-hydroxy acid structure and reaction conditions on
the relative yields of the products obtained.

The polymerisation and related reactions of the
enhydrosulphites have been studied kinetically using,
principally, gas evolution techniques. Two distinct
types of behaviour were observed, typified by the anhydrosulphites
of lactic and α-hydroxy isobutyric acids. In
the former case the anhydrosulphite ring is susceptible
to direct attack by alcohols with resulting regeneration
of the α-hydroxy group, this reaction forming the basis
of a bimolecular propogation step which leads to polymer
formation. α-Hydroxy isobutyric acid shows no such
reaction, however, the rate of ring opening being kinetically
independent of alcohol concentration. The polymerisation
of this anhydrosulphite has been studied with the
aid of radioactive tracer techniques.

Both types of decomposition are discussed, together
with the observed reluctance of anhydrocarboxy derivatives
of α-hydroxy acids to form high molecular weight polyesters,
in terms of ring structure and its effect on possible polymerisation
mechanisms. The relationship of these compounds to others showing similar behaviour is also discussed.

Date of Award	1966
Original language	English
Awarding Institution	Aston University