- Direct Catalytic Methanol-to-Ethanol Photo-conversion via Methyl Carbene
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A photo-driven direct methanol-to-ethanol conversion is reported with a robust gallium nitride catalyst under ambient conditions. This conversion is achieved with no solvent, ligand, additive, heating, atmosphere, or pressurization—just with light irradiation. A methyl carbene reaction intermediate is observed during the conversion, and the method enables access to the more useful (as both fuel and starting material) renewable resource ethanol. As an important effort to secure the sustainable “fossil alternative,” the direct conversion of the more readily available methanol to the more user-friendly, less toxic, and broadly applicable ethanol poses exciting potential as well as a tremendous scientific challenge. Herein, we report the first photo-driven one-step conversion of methanol to ethanol at ambient temperature, catalyzed by an ultra-stable gallium nitride semiconductor. Mechanistic studies revealed that methyl carbene (methylene), one of the most fascinating C1 building blocks in synthetic chemistry, was generated as a reaction intermediate, which potentially enables a green and novel method for generating carbene. We also found that methanol can be converted to n-propyl alcohol with the same catalyst through a simple change in reaction temperature, giving a unique selectivity and a high-value-added product. Methanol is an easily accessible fossil fuel alternative, but it is classified as hazardous and is also generally less valuable than other sources of carbon. A direct conversion of methanol to ethanol would provide facile access to a renewable starting material for applications as a safer fuel or an intermediate for the synthesis of the most demanded plastic, polyethylene (PE). This article reports the chemical transformation of methanol to ethanol and other higher alcohols, enabled by sp3-C–H methylation. In addition, the underlying chemistry can also be of importance for biochemistry and pharmaceutical chemistry, where methylation plays a pivotal role. The methanol-to-ethanol conversion is achieved in the presence of a robust catalyst and in only one step. No additive, solvent, or hazardous material is required.
- Liu, Mingxin,Wang, Yichen,Kong, Xianghua,Rashid, Roksana T.,Chu, Sheng,Li, Chen-Chen,Hearne, Zo?,Guo, Hong,Mi, Zetian,Li, Chao-Jun
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- 1-Butanol synthesis from ethanol over strontium phosphate hydroxyapatite catalysts with various Sr/P ratios
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Strontium phosphate hydroxyapatites (Sr-HAP) with various Sr/P molar ratios were synthesized under hydrothermal conditions. X-ray photoelectron spectroscopy revealed a close correlation between the near-surface and bulk Sr/P molar ratios of catalyst samples. Sr-HAP catalysts show high 1-butanol selectivity in the gas-phase conversion of ethanol. Sr-HAP catalysts with higher Sr/P molar ratios showed higher catalytic activity and 1-butanol selectivity. The density of both relatively strong basic sites and acidic sites was seen to increase with increasing Sr/P molar ratios, though the basic site density was significantly higher than the acidic site density. The rate-determining step in ethanol conversion over Sr-HAP catalysts was considered to be the dimerization process, as aldol condensation is mainly accelerated by base catalysis, which would explain why the Sr-HAP catalysts with higher basic site density showed higher catalytic activity and 1-butanol selectivity.
- Ogo, Shuhei,Onda, Ayumu,Iwasa, Yukina,Hara, Kenji,Fukuoka, Atsushi,Yanagisawa, Kazumichi
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- Nickel-Mediated Stepwise Transformation of CO to Acetaldehyde and Ethanol
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The insertion of CO into the Ni-C bond of synthetic Ni(II)-CH3 cationic complex ([1-CH3]+) affords a nickel-acetyl complex ([1-COCH3]+). Reduction of resultant [1-COCH3]+ by borohydrides produces CH3CHO, CH3CH2OH, and an Ni(0) compound ([1]0), which can react with CH3I to regenerate [1-CH3]+. By conducting deuterium labeling experiments, we have demonstrated that CH3CHO is the primary product from CH3CH2OH in such CO transformation reactions. In the reduction of [1-COCH3]+, the formation of CH3CHO competes with the loss of CH4, which leads to a Ni(0)-CO compound ([1-CO]0) as a minor product. Our results establish fundamental steps in the exploration of nickel-mediated CO transformation to valuable chemicals.
- Zhang, Ailing,Raje, Sakthi,Liu, Jianguo,Li, Xiaoyan,Angamuthu, Raja,Tung, Chen-Ho,Wang, Wenguang
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- Efficient synthesis of ethanol by methanol homologation using CO2 at lower temperature
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CO2 transformation is an important topic in green chemistry, and methanol homologation using CO2 is a promising route to produce ethanol. In this work, we studied this reaction using different homogeneous catalytic systems. It was found that a [RuCl2(CO)3]2/Co4(CO)12 bimetallic catalyst using LiI as a promoter and N-ethyl-2-pyrrolidone (NEP) as the solvent was very effective under mild conditions. The reaction could proceed efficiently at 160 °C, which is much lower than that reported before. The turnover frequency (TOF) of ethanol based on Ru was as high as 7.5 h-1 and the selectivity of ethanol in total products could reach 65.0 C-mol%, which are obviously higher than those reported in the literature. Ethanol was synthesized through cascade catalysis of a reverse water gas shift (RWGS) reaction and methanol homologation with syngas (CO/H2). The outstanding performance of the catalytic system originated from the excellent cooperation of the components. The catalyst could be reused at least five times without any obvious decrease of the catalytic performance. The effect of the solvent on this reaction was studied systematically. The mechanism was also discussed based on isotope labeling tests.
- Wang, Ying,Zhang, Jingjing,Qian, Qingli,Asare Bediako, Bernard Baffour,Cui, Meng,Yang, Guanying,Yan, Jiang,Han, Buxing
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supporting information
p. 589 - 596
(2019/02/14)
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- Synthesis of ethanol via a reaction of dimethyl ether with CO2 and H2
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Ethanol is currently produced via the catalytic hydration of ethylene or fermentation of foods. The synthesis of ethanol from cheap and renewable CO2 is of great importance, but the state of the art routes encounter difficulties, especially in reaction selectivity and activity. Here we show a strategy of ethanol synthesis from CO2, dimethyl ether (DME) and H2. The reaction can be effectively promoted with a Ru-Co bimetallic catalyst using LiI as a promoter in 1,3-dimethyl-2-imidazolidinone (DMI) solvent. The predominant product of this reaction was ethanol and the selectivity of ethanol in total products could reach 71.7 C-mol%. The selectivity of ethanol in the liquid product could reach 94.1%, which was higher than the reported routes using CO2/CO. To the best of our knowledge, this is the first work on ethanol synthesis from DME, CO2 and H2. The reaction mechanism is discussed based on a series of control experiments.
- Qian, Qingli,Cui, Meng,Zhang, Jingjing,Xiang, Junfeng,Song, Jinliang,Yang, Guanying,Han, Buxing
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supporting information
p. 206 - 213
(2018/01/12)
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- Photoreductive transformation of fluorinated acetophenone derivatives on titanium dioxide: Defluorination vs. reduction of carbonyl group
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Photoreductive transformation of mono- and di-fluoromethyl acetophenone (AP) derivatives on the P25 titanium dioxide (TiO2) has been studied in deaerated ethanol solution under UV irradiation. 2-Monofluoromethyl AP (MFAP) was stable in the dark and existed as keto form in ethanol, whereas 64% of 2,2-difluoromethyl AP (DFAP) transformed into hemiketal form (photocatalytically inactive form) under the same condition. Under the UV irradiation with the TiO2 particles, the reduction of MFAP afforded only the defluorinated ketone, while the reduction of DFAP provided not only defluorinated ketones but also a hydrogenated alcohol. The reduction of carbonyl group and defluorination of DFAP concurrently occurred on TiO2, in which the formation of MFAP was observed as an intermediate of the sequential defluorinations. These two parallel reactions were initiated by electron transfer from the surface defect sites (Tisd) to DFAP adsorbed on the TiO2 surface. A possible reaction mechanism for DFAP is proposed and discussed on the basis of thermodynamic data upon the C-F bond cleavage of anion radical species generated during the photocatalysis.
- Kohtani, Shigeru,Kurokawa, Takuya,Yoshioka, Eito,Miyabe, Hideto
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- Ruthenium Catalyzed Selective α- And α,β-Deuteration of Alcohols Using D2O
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Highly selective ruthenium catalyzed α-deuteration of primary alcohols and α,β-deuteration of secondary alcohols are achieved using deuterium oxide (D2O) as a source of deuterium and reaction solvent. Minimal loading of catalyst (Ru-macho), base (KOtBu), and low temperature heating provided efficient selective deuteration of alcohols making the process practically attractive and environmentally benign. Mechanistic studies indicate the D-O(D/R) bond activations by metal-ligand cooperation and intermediacy of carbonyl compounds resulting from dehydrogenation of alcohols.
- Chatterjee, Basujit,Gunanathan, Chidambaram
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supporting information
p. 4794 - 4797
(2015/10/12)
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- Simple and efficient catalytic reaction for the selective deuteration of alcohols
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A highly efficient system for the catalytic deuteration of α and β CH bonds of primary and secondary alcohols has been developed. The deuterium source is D2O. Together with the low catalyst loadings and the simple experimental setup, the reaction has direct application to the synthesis of bioactive isotopologues and the direct synthesis of fully deuterated substrates, such as ethanol-d6. The current system represents a significant advance in practicality for homogeneous metal catalyzed systems that carry out H/D exchange in organic substrates with water.
- Khaskin, Eugene,Milstein, David
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p. 448 - 452
(2013/08/25)
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