Novel catalysts for reactions between isocyanates and alcohols

摘要

Catalysts, which are free of tin, are described which are useful in the reaction between an isocyanate and an alcohol, which is a key step for preparing polyurethane polymers. The catalyst is a metal complex or salt of formula (1): [Zn(L1)l1(L2)l2(Y)x](1) in which: l11 and l2=0 or 1; with l1+l2=2, x=1 or 2, the symbol L1 represents a ligand which is a -dicarbonylato anion or the enolate anion of a -dicarbonyl compound or an acetylacetato anion derived from a -ketoester, when l1=2, the symbols L1 are identical or different, the symbol L2 represents an anionic ligand which is different from L1, and the symbol Y represents a neutral ligand; where the metal complex or salt C of formula (1) is not zinc diacetylacetonate.