- Synthesis of Ti-Al binary oxides and their catalytic application for C-H halogenation of phenols, aldehydes and ketones
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Traditional C–H halogenation of organic compounds often requires corrosive agent or harsh condition, and current researches are focused on the use of noble metals as catalyst. In order to give an efficient, benign, activity-adjustable and cost-effective system for halogenation, a series of Ti-Al mixed oxides are prepared as catalyst through sol-gel in this work. Characterizations reveal all catalysts contain more aluminum than titanium, but preparative conditions affect their composition and crystallinity. Monitoring of particle size, zeta potential and UV–vis of preparative solution reveals that formation of catalyst colloids undergoes chemical reaction, affecting catalyst morphology. In halogenation, all catalysts show moderate to high activities, copper chloride proves to be an effective halogen source rather than sodium chloride. The chlorination and bromination are better than iodization, phenol and ketone appear to be more appropriate substrates than aldehyde. Additionally, oxide backbone of catalyst is more durable than its organic components during recycling. This study may provide new catalytic materials for progress of C–H activation.
- Su, Peigen,Fan, Chao,Yu, Heng,Wang, Wanqin,Jia, Xin,Rao, Qifan,Fu, Chenxi,Zhang, Donghua,Huang, Benhua,Pan, Cheng,Zheng, Aqun,Sun, Yang
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- Cyclodienones. X. Reaction of Halo-cyclohexadien-1-ones with Phenols in the Presence of α-Picoline and Preparation of 4-Hydroxy- and 2-Hydroxyphenyl Aryl Ethers
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Reaction of 4-halocyclohexadienones such as 4-bromo-(1a), 4-chloro-2,4,6-tri-t-butyl-(1b), 2,4-dichloro-4,6-di-t-butyl-2,5-cyclohexadien-1-one, and 2,4-dichloro-2,6-di-t-butyl-3,5-cyclohexadien-1-one with phenols in the presence of α-picoline was carried out under various conditions.The reaction of 1a and 1b with phenols afforded the corresponding 2-aryloxy-4,6-di-t-butyl phenols together with various by-products.The AlCl3 catalyzed trans-t-butylation of 2-aroxy-4,6-di-t-butyl-phenols, which were obtained by the above reaction, afforded the corresponding 2-hydroxyphenyl aryl ethers.The similar reaction of 4-aroxy-2,4,6-tri-t-butyl-2,5-cyclohexadien-1-ones also afforded the corresponding 4-hydroxyphenyl aryl ethers.
- Tashiro, Masashi,Itoh, Takashi,Fukata, Gouki
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p. 416 - 420
(2007/10/02)
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