Structural features of poly(alkylene ether carbonate) diols and intermediates formed during their preparation

Capillary vapor‐phase chromatography and carbon‐13 nuclear magnetic resonance (NMR) have been used to elucidate the structure of poly(ethylene ether carbonate) diols and certain intermediates produced by the oligomerization of ethylene carbonate (EC) using monoethylene glycol (MEG) or diethylene glycol (DEG) as initiator and catalyzed by sodium stannate trihydrate. These diols are alternating copolymers of carbon dioxide and DEG which also contain smaller amounts of higher glycols as determined by comparing their 13 C NMR spectra to the spectra of model compounds. Diethylene glycol is an important reaction intermediate and is present in steady‐state concentrations. Although both 2‐hydroxyethyl carbonate and 2‐hydroxyethyl ether end groups are present at an intermediate stage in the reaction, only 2‐hydroxyethyl ether end groups are present at high EC conversion. Molecular weight builds as a smooth function of conversion and time.