The metathesis of polyunsaturated fatty esters using the homogeneousW(O-2,6-C6H3X2)2Cl4/Me4Sn catalytic systems
作者:B Marvey
DOI:10.1016/j.molcata.2003.11.026
日期:2004.4.13
Promoted with a small amount of Me4Sn, W(O-2,6-C6H3X2)(2)Cl-4 (X = Ph, Cl) complexes are highly active metathesis catalysts for polyunsaturated fatty esters. Upon metathesis of methyl linoleate, substrate conversions of ca. 95 and 78% were obtained in 2h with the W(O-2,6-C6H3Ph2)(2)Cl-4/Me4Sn and W(O-2,6-C6H3Cl2)(2)Cl-4/Me4Sn catalytic systems respectively. ne lower activity of the W(O-2,6-C6H3Cl2)(2)Cl-4/Me4Sn catalytic system was attributed to the highly deactivating nature of the Cl substituents on the o,o'-position of the aryloxide ligand. Highly electron-withdrawing Cl substituents cause the tungsten atom to be electron-deficient and thus more susceptible to attack by the electron-rich ester groups. However, the W(O-2,6-C6H3Cl2)(2)Cl-4/Me4Sn system was more selective towards dicarboxylic esters. The latter are interesting starting materials for the synthesis of polyesters and polyamides. The W(O-2,6-C6H3X2)(2)Cl-4/Me4Sn catalytic systems were rapidly deactivated by bromine-containing olefinic esters. Deactivation was attributed to a side reaction between the Br-group and the electron-deficient W-centre. (C) 2003 Elsevier B.V. All rights reserved.
W(O-2,6-C6H3X2)2Cl4/Bu4Sn as metathesis catalyst of 1-alkenes
作者:C. van Schalkwyk、H.C.M. Vosloo、J.A.K. du Plessis
DOI:10.1016/s1381-1169(98)00120-4
日期:1998.7
Tungsten compounds with aryloxo ligands, i.e., W(O-2,6-C6H3X2)(2)Cl-4 (X = Cl,Ph) and Bu,Sn, were investigated as catalytic systems for the metathesis of l-alkenes of varying carbon lenghts. The catalytic system was activated at 85 degrees C for 20 min prior to use. Optimum metathesis activity with l-alkenes was observed at 85 degrees C and a Sn/W molar ratio = 3. The W(O-2,6-C6H3X2)(2)Cl-4/Bu4Sn catalytic system is very active for the metathesis of l-alkenes with a carbon chain length of about six to eight and it favours a more polar solvent such as chlorobenzene. (C) 1998 Elsevier Science B.V. All rights reserved.
Aryloxide ligands in metathesis of olefins and olefinic esters: catalytic behaviour of W(OAr)2Cl4 complexes associated with alkyl-tin or alkyl-lead cocatalysts; alkylation of W(OAr)2Cl4 by SnMe4, Sn(n-Bu)4, Pb(n-Bu)4, MgNp2: synthesis of W(OAr)2Cl2(CHCMe3)(OR2) and W(OAr)2Cl(CHCMe3)(CH2CMe3)(OR2)
作者:Francoise Quignard、Michel Leconte、Jean Marie Basset
DOI:10.1016/0304-5102(86)85098-2
日期:1986.7
CRISP, GEOFFREY T.;COLLIS, MAREE P., AUSTRAL. J. CHEM., 41,(1988) N 6, C. 935-942