- Construction of Acid–Base Synergetic Sites on Mg-bearing BEA Zeolites Triggers the Unexpected Low-Temperature Alkylation of Phenol
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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.
- Xie, Jingyan,Zhuang, Wenxia,Zhang, Wei,Yan, Ning,Zhou, Yu,Wang, Jun
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p. 1076 - 1083
(2017/03/27)
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- Catalytic activity of a mordenite catalyst in alkylation of xylenols with methanol
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The catalytic activity of a palladium-containing mordenite catalyst in alkylation of 2,6-, 2,4-, 2,5-, 2,3-, 3,4-, and 3,5-xylenols with methanol was studied. The main and by-products of catalysis and the activity of the catalyst in synthesis of individual trimethylphenols were determined.
- Agaev,Madatzade
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p. 683 - 684
(2007/10/03)
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- Dienone-Phenol Rearrangements of 3-Acylcyclohexa-2,5-dienones: Kinetics and Mechanism
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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.
- Goodyear, Gary,Waring, Anthony J.
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p. 103 - 107
(2007/10/02)
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- SELECTIVE C-ALKYLATION OF PHENOL WITH METHANOL OVER ZEOLITES AND γ-ALUMINA
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The reaction of phenol with methanol has been carried out over zeolites HRENaY, HNaY and HY, and over γ-Al2O3, in the temperature range 250-450 deg C, in a fixed-bed continuous tubular reactor.C-Alkylates and no anisole were obtained as products over HY at 350 deg C and over γ-Al2O3 at 300-350 deg C, under conditions of complete methanol conversion.On the basis of the present results combined with those obtained in a parallel study on the methylation of phenol by anisole, a mechanism of the process is proposed.
- Beltrame, Paolo,Beltrame, Pier Luigi,Carniti, Paolo,Castelli, Antonella,Zuretti, Giovanni
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p. 649 - 656
(2007/10/02)
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- IMPROVED SYNTHESIS OF 2-HYDROXY-4,4,6-TRIMETHYL-2,5-CYCLOHEXADIENONE, USEFUL AS A FLAVORING ADDITIVE
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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.
- Buyck, Laurent de,Zi-Peng, Yao,Verhe, Roland,Kimpe, De Norbert,Schamp, Niceas
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- A DNMR STUDY OF ISOMERIC PHENOLS OBTAINED BY RING-OPENING, RING-CLOSURE OF 3-ISOPROPYL-2,4,6-TRIMETHYLPYRYLIUM SALTS: AN APPROACH TO THE REGIOSELECTIVITY OF THE RING-CLOSURE
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The regioselectivity of the syntheses of phenols via dissymmetrical pyrylium salts is found to be related to the difference in steric strain in the products as determined by conformational analysis.
- Rajoharison, Harivelo G.,Roussel, Christian,Berg, Ulf
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p. 2259 - 2262
(2007/10/02)
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- Polycyclic phenols, alcohols and ketones from phenols, cyclic alcohols and cyclic ketones using a nickel oxide/manganese oxide/magnesium oxide catalyst in presence of at least one of hydrogen and nitrogen
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At least one of a polycyclic phenol, a polycyclic alcohol and a polycyclic ketone is produced under hydrogenation conditions using a nickel oxide/manganese oxide/magnesium oxide catalyst by subjecting at least one of a monocyclic ketone, a monocyclic alcohol and a monocyclic phenol to said conditions and said catalyst.
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- Conversion of alkyl and aryl hydroxy compounds producing aldehyde, alcohol and ketone using manganese oxide/nickel oxide/magnesium oxide catalysts
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Alkyl and aryl hydroxy compounds are converted to aldehydes, alcohols, and ketones in the presence of hydrogen using a catalyst comprised of the oxides of manganese, nickel and magnesium.
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- The total synthesis of (+/-)hinesol and (+/-)epihinesol
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The tricyclic ketal ketones 15a and 15b have been obtained in an isomeric ratio of 9:1 (4 5 6 7 8 9 10 11 12 13 14 15a + 15b).Compound 15a was converted in seven (or eight) steps to (+/-)epihinesol (3) 29 32 48 49 47 (or 32 39 38 44 47) 50 3> and compound 38 was transformed into (+/-)hinesol (2) in five steps (38 76 77 62 63 2).The identity of epihinesol and agarospirol was confirmed by formation of a common epoxide.
- Lafontaine, Jacques,Mongrain, Marcel,Sergent-Guay, Mireille,Ruest, Luc,Deslongchamps, Pierre
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p. 2460 - 2476
(2007/10/02)
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