Carbodiimide metathesis catalyzed by vanadium oxo and imido complexes via imido transfer
作者:K.R. Birdwhistell、J. Lanza、J. Pasos
DOI:10.1016/s0022-328x(99)00142-4
日期:1999.7
Vanadium oxo and imido complexes: V(NC6H4Me)(OtBu)3 (1), V(NC6H4Me)Cl3 (2), V(O)(OtBu)3 (3), V(O)(OiPr)3 (4), V(O)(acac)2 (5), are catalysts for the metathesis of symmetrical carbodiimides (RNCNR, where R=cyclohexyl, isopropyl, and p-tolyl). At 138°C in p-xylene using 5 mol% of complexes 1–5, the above carbodiimides are metathesized to the asymmetrical carbodiimides: N-cyclohexyl,N′-p-tolylcarbodiimide
钒氧基和亚氨基配合物:V(NC 6 H 4 Me)(O t Bu)3(1),V(NC 6 H 4 Me)Cl 3(2),V(O)(O t Bu)3(3),V(O)(O i Pr)3(4),V(O)(acac)2(5)是对称碳二亚胺(RNCNR,其中R =环己基,异丙基和对甲苯基)复分解的催化剂)。在138℃下,在p二甲苯使用络合物5摩尔%1 - 5中,上述碳二亚胺的复分解,以非对称的碳二亚胺:Ñ -环己基,Ñ ' - p -tolylcarbodiimide(6),Ñ -异丙基,Ñ ' - p -tolylcarbodiimide(7),Ñ -环己基,Ñ '-isopropylcarbodiimide(8) 。取决于所使用的催化剂,在数分钟至数小时内达到碳二亚胺的平衡混合物。从气相色谱获得的产率为32%至70%。络合物2是最有效的催化剂,其周转频率大于100 h -1。羰基配合物(3– 5