The initiator efficiency in the tetrahydrofuran (THF) polymerization initiated by BF3 using epichlorohydrin (ECH) as the promotor is 2.5-6 times higher than that when ethylene oxi-de promotor was used. Five chain transfers

i.e. H2SO4

H2S2O7

water

butylene glycol and acetic anhydride (Ac2O) have been studied in this paper. With the addition of even a small amount of H2SO4 or H2S2O7 to the reaction system the polymerization does not occur. In the presence of Ac2O and 5 mol-% of the initiator the conversion reached 80% after 15min. of polymerization. In such a relatively rapid reaction the molecular weight ofthe product is little influenced by the conversion and feed amount of Ac2O and therefore

can be controlled around 2000 by varying the amount of initiator charged. The end-groups of the product are mainly hydroxyls with some acetoxyls (lower than 15%). The total average functionality of the end-groups is close to 2.