Treatment of a poly(ally1 alcohol) with ethyl chloroformate in an anhydrous organic solvent mixture has produced an insoluble polymer containing a high proportion of carbonate functions. An appreciable number of these functions exist in cyclic form, possibly as eight-membered rings, which have proved to be susceptible to nucleophilic attack in aqueous media. By means of these groups, water-soluble enzymes have been bound under mild conditions to the polymer, acting 6s an insoluble support, to produce active solid-phase enzymes.FOLLOWING the successful preparation of a cyclic carbonate of cellulose,l we have prepared carbonate derivatives of some synthetic polymers by similar methods. The greatest success was achieved with a poly(ally1 alcohol) (I). This was prepared by the radical polymerisation of ethyl acrylate followed by reduction with lithium aluminium h~d r i d e ;~,~ a ' head-to-tail ' polymerisation was assumed. The resulting polymer was extracted with water and the water-soluble, nondialysable fraction was isolated in a manageable form by lyophilisation. Sedimentation studies indicated that this polymer fraction was polydisperse and that the major proportion had a molecular weight of ca. 13,000. The polymer, in its finely divided state, was soluble in the dimethyl sulphoxide-triethylamine-1,4-dioxan solution required for carbonate formation. Dropwise addition of ethyl chloroformate to the cooled solution produced a vigorous reaction; the solution became yellow and triethylamine hydrochloride and the product polymer immediately began to precipitate. This rapid precipitation could have prevented conversion of all the hydroxy-1 S. 61,701/1969. groups available, but subsequent i.r. analysis indicated only a small hydroxy-group content in the product.Rigorously dried solvents were used throughout the reaction and washing procedures, to avoid nucleophilic opening of the reactive cyclic carbonate groups.l Conditions were chosen to limit the heating of the reaction mixture caused by rapid addition of chloroformate and extensive exposure of the polymer to the reagent was avoided. When the temperature rise was not controlled, and when a reaction time of more than 1 hr. was used, the product had a low cyclic carbonate content.Washing of the precipitate with 1,4-dioxan freed it from all excess of reagents, enabling dialysis to be used for removal of the triethylamine hydrochloride.The i.r. spectrum of the resulting white polymeric solid, poly(ally1 carbonate) , showed little hydroxyabsorption at 3300 cm.-l but strong absorptions at 1750 and 1810 cm.-l. The acyclic carbonate MeOCO-OMe has a carbonyl absorption at 1755 cm.-l, whereas the five-membered cyclic carbonate system has an a S. F. Withers, Ph.D. Thesis, University of Birmingham, 1969.
