527-54-8Relevant articles and documents
Construction of Acid–Base Synergetic Sites on Mg-bearing BEA Zeolites Triggers the Unexpected Low-Temperature Alkylation of Phenol
Xie, Jingyan,Zhuang, Wenxia,Zhang, Wei,Yan, Ning,Zhou, Yu,Wang, Jun
, p. 1076 - 1083 (2017/03/27)
Novel Mg-bearing BEA zeolites are synthesized to simultaneously endow significantly enhanced basicity without compromising acidity over the zeolite framework. Serving as efficient solid acid–base bifunctional catalysts, they achieve the liquid-phase selective methylation of phenol with methanol to produce o- and p-cresol (o/p=2) under mild conditions. The method is readily extendable to the alkylation of phenols with various alcohols. Stereo- and regioselectivity (>95 % for p-product) was attained on the alkylation of phenol with bulky tert-butyl alcohol, rendering the first acid–base cooperative shape-selective catalysis relying on the basicity of zeolites. A preliminary mechanistic analysis reveals that the remarkable activity and shape-selectivity come from the superior special acidic–basic synergetic catalytic sites on the uniform microporous channels of the BEA zeolite.
Dienone-Phenol Rearrangements of 3-Acylcyclohexa-2,5-dienones: Kinetics and Mechanism
Goodyear, Gary,Waring, Anthony J.
, p. 103 - 107 (2007/10/02)
The dienone-phenol rearrangements of 3-acetyl-4,4-dimethyl-, 3-ethoxycarbonyl-4,4-dimethyl-, and 3-acetyl-4,4,5-trimethylcyclohexa-2,5-dienones have been studied.The 3-acetyl and 3-ethoxycarbonyl compounds rearrange under acidic conditions to give the 3-acyl-4,5-dimethylphenols, via a 4-5-methyl migration.Kinetic measurements were made which also allowed the protonation (basicity) behaviour of the 3-acetyl-4,4-dimethyl compound to be determined.The acetyl group considerably reduces the basicity of the dienone.At high acidities, where the dienone is largely protonated, it rearranges four times faster than the 4,4-dimethyl-, and 100 times faster than the 3,4,4-trimethyl dienone, showing the acetyl group to enhance the reactivity of the cation.At low acidities the amount of reactive cation, and thus the observed rate of rearrangement, is small.The effect of the acetyl group on the basicity and reactivity are attributed to its destabilising the dienone cation relative to the neutral dienone, and relative to the cation produced by rearrangement.The 3-ethoxycarbonyl group shows similar behaviour.The acceleration of rearrangement is also found for 3-acetyl-4,4,5-trimethylcyclohexa-2,5-dienone, the cation of which reacts slowly, but still at least 60 times faster than the 3,4,4,5-tetramethyl analogue.
IMPROVED SYNTHESIS OF 2-HYDROXY-4,4,6-TRIMETHYL-2,5-CYCLOHEXADIENONE, USEFUL AS A FLAVORING ADDITIVE
Buyck, Laurent de,Zi-Peng, Yao,Verhe, Roland,Kimpe, De Norbert,Schamp, Niceas
, p. 75 - 80 (2007/10/02)
The title dienone 1, useful for modification, improvement or increasing organoleptic properties of tobacco, sucrose syrups, flavored beverages, was prepared in 40-55percent overall yield from isophorone, by chlorination of 2-hydroxy-isophorone (2), rearrangement into 6-chloro-2-hydroxyisophorone (5) and dehydrochlorination.An excellent yield of 3-chloro-2-hydroxy-4,4,6-trimethyl-2,5-cyclohexenone (12) was obtained by chlorination of 5 followed by dehydrohalogenation.
