Technical parameters of 1,5,9-cyclododecatriene (CDT) syntheses run over titanium catalysts -: Part 2.: Catalysts based on Ti(OR)4 or Ti(II) complexes, and heterogeneous catalysts

A review covering Ti(OR (1))(4)(TiCl4)/R(3-n)(2)AIX(n) (n = 0.5-3; R-1 = Et, Bu, i-Bu, sec-Bu; R-2 = Me, Et, OBu, O(i-Bu), O(sec-Bu)), Ti(II) complexes, and Ziegler supported (heterogeneous) systems used as catalysts for cyclotrimerization of butadiene. As compared with the TiCl4-based catalysts, those based on alkylorthotitanates Ti(OR)(4) and Ti(OR)(n)X4-n are less sensitive to water, yet Ti(OBu)(4)/Et2AlCl or Ti(OBu)(4)/(i-Bu)(2)AlCl are less active (60-100 g CDT/(mmol Ti.h)) and moderately selective (80-90%) toward CDT In terms of catalyst activity, Ti(OR)(4) is near to TiCl4, but Ti(OR)(4) gives (E,E,E)-CDT in higher yield. Very active Ti(II) catalysts, highly selective toward (ZEE)-CDT, are extremely sensitive to H2O and O-2 Heterogeneous catalysts are much less effective and yield butadiene oligomers and 1,4-polybutadiene.