Origin of the selectivity in the gold-mediated oxidation of benzyl alcohol

详细信息	查看全文 | 推荐本文 |

• 作者：Juan Carlos F. Rodrí ; guez-Reyes^a ; Cynthia M. Friend^a ; Robert J. Madix^b ; ^{rmadix@seas.harvard.edu}
• 关键词：Gold ; Catalysis ; Oxidation ; Alcohols
• 刊名：Surface Science
• 出版年：2012
• 期刊代码：104_00396028
• 类别：ch
• 出版时间：August, 2012
• 卷：606
• 期：15-16
• 页码：1129-1134
• 文件大小：716 K

摘要

Benzyl alcohol has received substantial attention as a probe molecule to test the selectivity and efficiency of novel metallic gold catalysts. Herein, the mechanisms of benzyl alcohol oxidation on a gold surface covered with atomic oxygen are elucidated; the results show direct correspondence to the reaction on gold-based catalysts. The selective, partial oxidation of benzyl alcohol to benzaldehyde is achieved with low oxygen surface concentrations and takes place through dehydrogenation of the alcohol to form benzaldehyde via a benzyloxy (C₆H₅-CH₂O) intermediate. While in this case atomic oxygen plays solely a dehydrogenating role, at higher concentrations it leads to the formation of intermediates from benzaldehyde, producing benzoic acid and CO₂. Facile ester (benzyl benzoate) formation also occurs at low oxygen concentrations, which indicates that benzoic acid is not a precursor of further oxidation of the ester; instead, the ester is produced by the coupling of adsorbed benzyloxy and benzaldehyde. Key to the high selectivity seen at low oxygen concentrations is the fact that the production of the aldehyde (and esters) is kinetically favored over the production of benzoic acid.