Stereochemistry of the hydrogenation of o-xylene over a silica-supported polysilazane–platinum complex

✍ Scribed by Chun-Wei Chen; Long Zhang; Shi-Jian Su; Mei-Yu Huang; Su-Fen Mao; Ying-Yan Jiang

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 351 KB
• Volume: 7
• Category: Article
• ISSN: 1042-7147
• DOI: 10.1002/(sici)1099-1581(199608)7:8<711::aid-pat574>3.0.co;2-j

✦ Synopsis

Silica-supported polysilazane (Si0,-Si-N), and its platinum complex (SiO,-Si-N-Pt) were prepared. It was found that Si0,-Si-N-Pt can catalyze hydrogenation of o-xylene under mild conditions (4O-5O0C, 1 atm). The products of the reaction were cis-and trans-1,2-dimethylcyclohexane. The formation of trans-l,2-dimethylcyclohexane may be adequately explained according to the 'roll-over' model. The stereoselectivity was influenced by temperature and catalyst concentration, the proportion of the cis isomer decreasing with an increase in each of the two factors. The effects of other reaction parameters, such as the NIPt mole ratio in the complex, solvents and reaction time, etc. on the hydrogenation of o-xylene were also studied. The Si02-Si-N-Pt catalyst is very stable in reaction and turnover numbers amount to 200 in 80 hr.