REACTION-MECHANISM OF THE FORMATION OF CARBORAN-CONTAINING OLIGOCARBORANECARBONATE METHACRYLATES

The acylation of o-carboranediol under conditions of the low temperatu re acceptor catalytic telomerization can be carried out with the both nucleophilic and general base catalysis, the latter beeng considerably more effective. The high efficiency of the general base catalysis is determined by the formation of a specific reaction complex between o-c arboranediol and triethylamine demonstrated by PMR spectra. Triethylam ine-o-carboranediol complex includes both HO-groups of diol (1 : 1 com plex); this is connected to their ortho-arrangement (i.e. specific ort ho-effect is displayed). This new ortho-effect is the reason of the di fference in the reactivity of two HO-groups of a symmetric molecule of o-carboranediol: under mild conditions the reaction occurs only at on e HO-group. The realization of the ortho-effect allows to obtain indiv idual oligomers with sufficiently high molecular weight via step-wise process. The data obtained on the mechanism of the acylation of o-carb oranediol by chloroformates have allowed to optimize experimental cond itions of the synthesis of carborane containing oligocarbonate methacr ylates and to develop effective techniques of the preparing oligomers of a perfect structure.