Journal
INORGANICA CHIMICA ACTA
Volume 361, Issue 11, Pages 3315-3321Publisher
ELSEVIER SCIENCE SA
DOI: 10.1016/j.ica.2008.01.012
Keywords
grafting; chromium; silica; alpha-H elimination; alkylidene
Categories
Ask authors/readers for more resources
The grafting of tetraneopentylchromium(IV) onto the surface hydroxyls of silica has been investigated by varying both the method of deposition and the nature of the silica support. Reaction of the volatile organometallic with the silica surface in vacuo is compared with reaction in solution. A faster reaction but a lower ultimate Cr loading was obtained using the solution deposition technique. The reactions of the organometallic compound with Aerosil 200, a fumed silica often used to model catalyst supports, and Sylopol 952, a silica gel used as a carrier for chromium-based ethylene polymerization catalysts, are compared. After thermal pretreatment at 200 degrees C, grafting on both supports yields bis(neopentyl) chromium(IV) fragments regardless of the grafting method used, suggesting that a paired arrangement of the surface hydroxyl groups exists on both types of silicas. The higher Cr loading achieved on the silica gel is attributed to its higher surface area. Thermally-induced neopentane elimination from the grafted bis(neopentyl) chromium(IV) fragments occurs at the same rate and with the same stoichiometry for both Aerosil-and Sylopol-supported materials. Consequently, interactions of the grafted organometallic fragments with nearby siloxanes appear to be unimportant in the early stages of the transformation of bis(alkyl) chromium(IV) to the alkylidene. (C) 2008 Elsevier B.V. All rights reserved.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available