RELATIVE REACTIVITY OF ISOCYANATE GROUPS OF ISOPHORONE DIISOCYANATE. UNEXPECTED HIGH REACTIVITY OF THE SECONDARY ISOCYANATE GROUP.

Abstract

Isophorone diisocyanate (IPDI) is widely used in polyurethane coatings and adhesives. Its extensive use is partly attributable to the differential reactivity of its two NCO groups. The question of which isocyanate group is more reactive has received little attention, although it has been assumed that the primary NCO group is more reactive. The question is complicated by the presence of two geometric isomers (about 3:1) in commercially available IPDI. This article concerns the identity of the more reactive NCO group in the major isomer of IPDI.