| 摘要 |
Trialkylboron-monoammines are made by passing dry ammonia into a liquefied trialkylboron, in an atmosphere of nitrogen, and recovering the white solid product and purifying it by distillation. The preparations of trimethyl and triethyl boron monoammine are described. Trimethyl boron may be obtained by reacting methyl magnesium iodide with boron trifluoride etherate.ALSO:Gels of an unsaturated polyester dissolved in a polymerizable monomer e.g. styrene are made by incorporating in the solution a gelling catalyst consisting of an ammoniacal complex of a trialkyl boron compound. The gel may be subsequently polymerized by incorporating in it before or after manufacture one or more polymerization catalysts. The unsaturated polyester consists of the reaction product of a polyhydroxylated compound with an alpha-beta-unsaturated di-acid and optionally a saturated diacid, such as the condensate of maleic and phthalic acids and/or anhydrides with propylene glycol. The polyester and monomer may be gelled in the presence of fillers such as calcium carbonate, and reinforcements such as a preform of glass fibre or a fabric. The gelling catalyst may be trimethyl or triethyl-boron-monoamine. The polymerization catalyst is preferably a peroxy compound such as dicumyl peroxide, p-tert.-butyl-cumene hydroperoxide, dibenzal di-peroxide, tert. butyl peracetate, tert. butyl perbenzoate, tert. butyl peroxide, or 2,2,bis (tert. butyl-peroxy) butene. The gelling is preferably effected in a mould, and the moulded preform polymerized subsequently at room or elevated temperature. |
