1516-08-1Relevant articles and documents
Direct Catalytic Methanol-to-Ethanol Photo-conversion via Methyl Carbene
Liu, Mingxin,Wang, Yichen,Kong, Xianghua,Rashid, Roksana T.,Chu, Sheng,Li, Chen-Chen,Hearne, Zo?,Guo, Hong,Mi, Zetian,Li, Chao-Jun
, p. 858 - 867 (2019)
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.
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Trzupek et al.
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Efficient synthesis of ethanol by methanol homologation using CO2 at lower temperature
Wang, Ying,Zhang, Jingjing,Qian, Qingli,Asare Bediako, Bernard Baffour,Cui, Meng,Yang, Guanying,Yan, Jiang,Han, Buxing
supporting information, p. 589 - 596 (2019/02/14)
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.
Photoreductive transformation of fluorinated acetophenone derivatives on titanium dioxide: Defluorination vs. reduction of carbonyl group
Kohtani, Shigeru,Kurokawa, Takuya,Yoshioka, Eito,Miyabe, Hideto
, p. 68 - 74 (2016/06/14)
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.
