Catalyst compsns. for polymerisation of heterocyclic oxygen and sulphur cpds. - made by reacting silica with an organo-aluminium cpd. and an organic cpd. with mobile hydrogen in selected solvent medium

摘要

A catalyst compsn. is obtd. by (a) forming a suspension of dehydrated silica in an anhydrous, polar or non polar aprotic liq; (b) adding to the resulting suspension a soln. in an inert anhydrous solvent of at least one Al cpd. contg. at least one Al-C bond, chosen from (i) alkylaluminium cpds. of formula A1R1(3-n)xn (I) (in which n is 0, 1 or 2, x is halgoen, and R1 is 1-24C organic gp) and (ii) Al cpds. of formula (II) (in which p is 0, 1 or 2, Z1 = a gp. of formula (III) or (iv); Z2 is a gp. of formula (v) or (vi), R2, R3, R4 and R5 are each 1-24C organic gps. and R1 and R5 may together complete a ring), the addn. being made under such conditions that at least part of the silanol gps. of the silica react with the Al cpd. with the formation of Si-O-Al bonds, and the Al cpd. being used in amts. such that the number of C-A1 bonds is in excess w.r.t. the number of silanol gps. on the silica; (c) if necessary, eliminating excess of the Al cpd. by washing with an aprotic solvent; (d) adding to the resulting suspension at least one organic cpd. with a mobile H atom of formula R6-YH (III) (in which R6 is an organic gp. and Y is -O-, -S-, or -NR7- in which R7 is H or an organic gp. the (III) being used in excess w.r.t. the Si-O-Al bonds formed during stage (a) and the addn. made under conditions promoting exchange of the gps. R1 attached to the Al atom(s) by gps. -Y-R6 and formation of a hydrocarbon, (e) opt. eliminating any hydrocarbon formed in stage (d) and (f) recovering a mixt. comprising the solid formed in stage (d) excess (III), the aprotic liq(s) used in stages (a) and (c) an opt. at least part of the inert anhydrous solvent used in stage (b) and at least part of the hydrocarbon formed in stage (d). USE/ADVANTAGE - The prods. are useful as catalystic systems for the (co)polymerisation of heterocyclic O or S contg. cpds. contg. one or more heteroatoms and esp. for (co)polymerisation of epoxides, lactones, and lactides, partic. ethylene oxide, propylene oxide, beta-butyrolactone, epsilon-caprolactone and 3,6-dimethyl-1,4- dioxan-2,5-dione (claimed).