6669-13-2Relevant articles and documents
Vapor-phase alkylation of phenol with tert-butyl alcohol catalyzed by H3PO4/MCM-41
Ghiaci, Mehran,Aghabarari, Behzad
, p. 759 - 764 (2010)
The catalytic performance of Al-MCM-41 containing 5-35 wt H 3PO4 was studied for the vapor-phase alkylation of phenol with tert-butyl alcohol (TBA) from 383 to 493 K. 4-Tert-butyl phenol was produced as the main product with moderate selectivity. The product distribution depends on the reaction temperature, number of acid sites, and the Broensted to Lewis sites ratios. A lower molar ratio of reactants (TBA/phenol = 2) and a higher space velocity facilitated the production of 4-tert-butyl phenol. The influence of various parameters such as temperature, reactant feed molar ratio, feed rate, and time on stream were investigated for conversion yield and product selectivity.
Alkylation of Phenol with tert-Butanol in a Draining-Film Reactor
Maksimov, A. L.,Mel’chakov, I. S.,Terekhov, A. V.,Zanaveskin, L. N.
, p. 569 - 575 (2021/07/26)
The alkylation of phenol with tert-butanol in a displacement draining-film reactor on a heterogeneous catalyst, Beta zeolite, was evaluated. Optimum process conditions ensuring the maximal p-tert-butylphenol yield were determined: phenol:tert-butanol molar ratio (3–3.5):1, superficial liquid velocity 1.0–1.5 m3 m–2 h–1, and temperature 100°C–110°C. A procedure ensuring 100% conversion of tert-butanol and isobutylene (a by-product formed from tert-butanol) was observed.
Sodium Butylated Hydroxytoluene (NaBHT) as a New and Efficient Hydride Source for Pd-Catalysed Reduction Reactions
Sharif, Sepideh,Rodriguez, Michael J.,Lu, Yu,Kopach, Michael E.,Mitchell, David,Hunter, Howard N.,Organ, Michael G.
supporting information, p. 13099 - 13103 (2019/10/28)
NaBHT (sodium butylated hydroxytoluene), a hindered and soluble base for the efficient arylation of various base-sensitive amines and (hetero)aryl halides has been found to have an unanticipated role as a hydride donor to reduce (hetero)aryl halides and allylic acetates. Mechanistic studies have uncovered that NaBHT, but not BHT, can deliver multiple hydrides through oxidation of the benzylic methyl group in NaBHT to the aldehyde. Further, performing the reduction with NaBHT-d20 has revealed that the redox-active benzylic position is not the only hydride donor site from NaBHT with one hydride in three coming, presumably, from the tert-butyl groups. The reduction works well under mild conditions and, incredibly, only consumes 20 percent of the NaBHT in the process; the remaining 80 percent can be readily recovered in pure form and reused. This, combined with the low cost of the material in ton-scale quantity, makes it practical and attractive for wider use in industry at scale.
Singlet vs Triplet Reactivity of Photogenerated α,n-Didehydrotoluenes
Pedroli, Chiara,Ravelli, Davide,Protti, Stefano,Albini, Angelo,Fagnoni, Maurizio
supporting information, p. 6592 - 6603 (2017/07/15)
The reactivity of α,n-didehydrotoluenes (DHTs) in protic media (organic/aqueous mixtures) was explored by means of a combined computational and experimental approach. These intermediates were generated via a photoinduced double elimination process occurring in (chlorobenzyl)trimethylsilanes and led to the formation of a varied products distribution, depending on the isomer tested. Irradiation of ortho- and para-derivatives resulted, respectively, in the formation of triplet α,2- and α,4-DHTs, whose diradical reactivity led to both radical and polar products. On the other hand, irradiation of the meta-precursor led to the singlet α,3-DHT isomer. The latter showed a marked preference for the formation of polar products and this was rationalized, as supported by computational evidence, via the involvement of a zwitterionic species arising through interaction of the nucleophilic solvent with the benzylic position of the DHT.
A study of diketopiperazines as electron-donor initiators in transition metal-free haloarene-arene coupling
Cumine, Florimond,Zhou, Shengze,Tuttle, Tell,Murphy, John A.
, p. 3324 - 3336 (2017/04/21)
Several diketopiperazines have been shown to promote carbon-carbon coupling between benzene and aryl halides in the presence of potassium tert-butoxide and without the assistance of a transition metal catalyst. The structure of the diketopiperazine has an influence on its reductive potential and can help to promote the coupling of the more challenging aryl bromides with benzene.
Cleavage of the lignin β-O-4 ether bond: Via a dehydroxylation-hydrogenation strategy over a NiMo sulfide catalyst
Zhang, Chaofeng,Lu, Jianmin,Zhang, Xiaochen,Macarthur, Katherine,Heggen, Marc,Li, Hongji,Wang, Feng
supporting information, p. 6545 - 6555 (2018/06/06)
The efficient cleavage of lignin β-O-4 ether bonds to produce aromatics is a challenging and attractive topic. Recently a growing number of studies have revealed that the initial oxidation of CαHOH to CαO can decrease the β-O-4 bond dissociation energy (BDE) from 274.0 kJ mol-1 to 227.8 kJ mol-1, and thus the β-O-4 bond is more readily cleaved in the subsequent transfer hydrogenation, or acidolysis. Here we show that the first reaction step, except in the above-mentioned pre-oxidation methods, can be a Cα-OH bond dehydroxylation to form a radical intermediate on the acid-redox site of a NiMo sulfide catalyst. The formation of a Cα radical greatly decreases the Cβ-OPh BDE from 274.0 kJ mol-1 to 66.9 kJ mol-1 thereby facilitating its cleavage to styrene, phenols and ethers with H2 and an alcohol solvent. This is supported by control experiments using several reaction intermediates as reactants, analysis of product generation and by radical trap with TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy) as well as by density functional theory (DFT) calculations. The dehydroxylation-hydrogenation reaction is conducted under non-oxidative conditions, which are beneficial for stabilizing phenol products.
Air-stable palladium(0) phosphine sulfide catalysts for Ullmann-type C-N and C-O coupling reactions
Majumder, Arpi,Gupta, Ragini,Mandal, Mrinmay,Babu, Madhu,Chakraborty, Debashis
, p. 23 - 34 (2015/03/05)
This paper describes an efficient procedure for palladium(0)-catalyzed N-arylation and O-arylation of aryl halides by Ullmann-type cross coupling reaction under mild reaction conditions in a short reaction time. Two phosphine sulphide ligands and their corresponding Pd(0) complexes namely [Pd(p2S2)(dba)] and [Pd(pp3S4)(dba)], were synthesized, where p2S2 is 1,2-bis(diphenylphosphino)ethane disulfide, pp3S4 is tris[2-(diphenylphosphino)ethyl]phosphine tetrasulfide and dba is dibenzylideneacetone. Optimal reaction conditions were determined for the arylation reactions using iodobenzene and benzimidazole by varying temperature, solvent, base and catalyst loading. The cross coupling reactions were carried out taking iodobenzenes/bromobenzenes and a wide variety of substituted aryl amines/phenols/alcohols with different steric and electronic properties to afford the desired N-aryl amines/diaryl ethers/alkyl aryl ethers in good to excellent yield (70-94%).
Iron-mediated direct arylation of unactivated arenes in air
Huang, Yuxing,Moret, Marc-Etienne,Klein Gebbink, Robertus J. M.
supporting information, p. 3788 - 3793 (2014/06/24)
Biaryls are a common motif in both natural and synthetic chemicals. Several methods have recently been reported for the preparation of these compounds using direct arylation catalyzed by iron, other base metals, or transition-metal-free systems. To date, these methods have all required inert and/or forcing conditions, which limited their application in routine organic synthesis. In this article we report a protocol for direct arylation using a convenient FeCl3/1,10-phenanthroline system as precatalyst. The reaction proceeds under mild conditions (100 °C), under air, and with non-distilled solvent. A simple, environmentally benign catalytic system based on iron trichloride and phenanthroline has been developed for the direct arylation of unactivated arenes with aryl halides under air. Copyright
Preparation and catalytic performance of perfluorosulfonic acid-functionalized carbon nanotubes
Zhang, Mengxiao,Li, Cuican,Hua, Weiming,Yue, Yinghong,Gao, Zi
, p. 1874 - 1882 (2015/09/28)
Perfluorosulfonic acid-functionalized carbon nanotubes were prepared by liquid deposition of the perfluorosulfonic acid-polytetrafluoroethylene copolymer and characterized by N2 adsorption, scanning electron microscopy, transmission electron mi
Enhanced activity over alkyl/aryl functionalized porous pillared-zirconium phosphates in liquid-phase reaction
Liu, Ke,Wang, Xueyan,Ding, Shengda,Li, Ying,Hua, Weiming,Yue, Yinghong,Gao, Zi
, p. 84 - 89 (2013/11/06)
A series of porous pillared-zirconium phosphates functionalized with methyl, ethyl, propyl and phenyl groups were prepared and characterized by SEM, 29Si MAS NMR, TG and N2 adsorption. Their total surface acidity and accessible one were measured by potentiometric titration of n-butylamine and liquid phase 2,6-di-tert-butyl-pyridine adsorption, respectively. The catalytic behaviors of these hybrid materials for alkylation of hydroquinone and esterification of lauric acid were compared. Not the total acid sites but the accessible ones play a crucial role in both reactions of alkylation and esterification. The accession for acid sites can be enhanced by the introduction of alkyl/aryl groups, due to the improved hydrophobicity of the surface.