| 摘要 |
<p>Prodn. of (cyclo)aliphatic substd. 2,4,6-triketohexahydrotriazines (I) comprises catalytic trimerisation of corresp. isocyanates (II) at 80-200 degrees, esp. 120-180 degrees C until conversion is 50%, then recovering (I) conventionally. Reaction is carried out in presence of 0.1-5 wt.% on (II) of a catalyst system contg. epoxides (III) and tert. amines of formula R1R2R3N (N) at 1-6 : 1 mole ratio. In the formula each R is independently H, (cyclo)alkyl, aralkyl or aryl, opt. substd. by halo or OH. R1 are each as R, or (cyclo)alkyl, aryl or aralkyl contg. >=1 epoxy gp. 2R, 2R1 or R + R1 can also form a cycloaliphatic ring. R1 is 1-2C alkyl. R2 and R3 are each (cyclo)alkyl or aryl opt. substd. by aryl or PH, or are joined together by O, S or NR2 bridges. Pref. unreacted (II) is recovered by thin-film distn. and recycled. (I) are intermediates for coating compsns. The catalyst is easily removed, for reuse, during the final distn. Yields of (I) are practically quantitative and prods. are free of monomer and almost free of higher adducts.</p> |
