Rapid Catalysis for Aerobic Oxidation of Alcohols Based on Nitroxyl-Radical-Free Copper(II) under Ambient Conditions

Abstract

Aerobic oxidation of alcohols is one of the most important methods for the production of aldehydes. In this work, a scalable, continuous flow synthesis method for the aerobic oxidation of alcohols using a copper catalyst with redox-active ligand and molecular oxygen (O 2 , air) was developed. The yield of benzaldehyde could reach 93.4% by optimizing the following conditions, such as copper content, solvent, O 2 flow rate, and temperature. This synthesis method exhibited excellent functional group compatibility for various alcohols with excellent reactivity and reusability, avoiding the use of some nitroxyl radicals (TEMPO, ABNO) or base additives. In the microchannel reactor, the total reaction time could be reduced from 24 h to 40 min, and a simplified kinetic model was established.

Complexation behavior of copper and zinc divalent ions towards diisatin malonyl dihydrazone ligand with biological and catalytic assessments

“…Within solvent‐free atmosphere and chloroform, the progress of the epoxidation of CHex exhibited a considerable enhancement for the yielding and selectivity percentages of CHexO; however, they assigned less effectiveness for CuLm and ZnLm compared to that within acetonitrile (Table 8). In chloroform, the yielding percentages were 87% and 84% of CHexO with little less yielding than that in acetonitrile with modified conversion percentages (100% and 96%) within both CuLm and ZnLm catalysts, respectively 67 . The powered nature of covalence (organic strength) of chloroform (poor polar solvent) can improve the reactivity of CHex towards the oxidation in the solvent with more solubility; however, it could not perform the oxygen transfer action because of its less polar nature and less miscibility between the inorganic oxidant (H 2 O 2 ) and the organic substrate (CHex) 68 .…”

“… 31 In addition, the high selectivity for the epoxidation reaction could be explained with the hydrogen bonding. The formation of hydrogen bonds between the polar solvent (acetonitrile) and CHexO, which avoided the overoxidation process, could modify the yielding and selectivity of CHexO 67 …”

“…The formation of hydrogen bonds between the polar solvent (acetonitrile) and CHexO, which avoided the overoxidation process, could modify the yielding and selectivity of CHexO. 67 Within solvent-free atmosphere and chloroform, the progress of the epoxidation of CHex exhibited a considerable enhancement for the yielding and selectivity percentages of CHexO; however, they assigned less effectiveness for CuLm and ZnLm compared to that within acetonitrile (Table 8). In chloroform, the yielding percentages were 87% and 84% of CHexO with little less yielding than that in acetonitrile with modified conversion percentages (100% and 96%) within both CuLm and ZnLm catalysts, respectively.…”

“…In chloroform, the yielding percentages were 87% and 84% of CHexO with little less yielding than that in acetonitrile with modified conversion percentages (100% and 96%) within both CuLm and ZnLm catalysts, respectively. 67 The powered nature of covalence (organic strength) of chloroform (poor polar solvent) can improve the reactivity of CHex towards the oxidation in the solvent with more solubility; however, it could not perform the oxygen transfer action because of its less polar nature and less miscibility between the inorganic oxidant (H 2 O 2 ) and the organic substrate (CHex). 68 Similarly, the variation in the polarity between CHex and H 2 O 2 in the absence of a solvent caused less efficiency of CuLm and ZnLm catalysts compared to that in acetonitrile, in which the yielding percentages were 85% and 83% of CHexO with 93% and 94% of selectivity using CuLm and ZnLm, respectively.…”

Study on the Morphologic and Flow State of Polyacrylonitrile Particles in a Microchannel Reactor

“…In recent years, microchannel reactor technology has been widely used in the field of chemistry and the chemical industry. − Microchannel reactors are small continuous tubular reactors composed of tiny channels. Compared with batch reactors, microchannel reactors have the advantages of a large specific surface area, fast heat and mass-transfer rates, high mixing efficiency, strong process safety, and more precise control of process parameters. − Due to these advantages, polymers synthesized by free-radical polymerization using microchannel reactors have controllable molecular weights and narrower molecular weight distributions. − However, in the PAN precipitation polymerization reaction, the reaction products can easily be deposited on the walls of the microchannel reactor. This can lead to a sharp increase in the pressure drop in the reactor and even blockage.…”