Efficient and convenient oxidation of alcohols to aldehydes and ketones with molecular oxygen mediated by In(NO3)3 in ionic liquid [C12mim][FeBr4]

A simple, efficient, and ecofriendly procedure for the aerobic oxidation of alcohols to aldehydes and ketones in the presence of In(NO₃)₃/[C₁₂mim][FeBr₄] in aqueous media has been developed. The oxidation reactions afford the target products in good to high yields and no over-oxidation was observed. The products can be separated by a simple extraction with dichloromethane, and the system can be recycled and reused without loss of activity.     

Ruthenium-Catalyzed C−C Coupling of Terminal Alkynes with Primary Alcohols or Aldehydes: α,β-Acetylenic Ketones (Ynones) via Oxidative Alkynylation

The first metal-catalyzed oxidative alkynylations of primary alcohols or aldehydes to form α,β-acetylenic ketones (ynones) are described. Deuterium labelling studies corroborate a novel reaction mechanism in which alkyne hydroruthenation forms a transient vinylruthenium complex that deprotonates the terminal alkyne to form the active alkynylruthenium nucleophile.     

Continuous Flow Electrochemistry Enables Practical and Site-Selective C−H Oxidation

The selective oxygenation of ubiquitous C(sp³)−H bonds remains a highly sought-after method in both academia and the chemical industry for constructing functionalized organic molecules. However, it is extremely challenging to selectively oxidize a certain C(sp³)−H bond to afford alcohols due to the presence of multiple C(sp³)−H bonds with similar strength and steric environment in organic molecules, and the alcohol products being prone to further oxidation. Herein, we present a practical and cost-efficient electrochemical method for the highly selective monooxygenation of benzylic C(sp³)−H bonds using continuous flow reactors. The electrochemical reactions produce trifluoroacetate esters that are resistant to further oxidation but undergo facile hydrolysis during aqueous workup to form benzylic alcohols. The method exhibits a broad scope and exceptional site selectivity and requires no catalysts or chemical oxidants. Furthermore, the electrochemical method demonstrates excellent scalability by producing 115 g of one of the alcohol products. The high site selectivity of the electrochemical method originates from its unique mechanism to cleave benzylic C(sp³)−H bonds through sequential electron/proton transfer, rather than the commonly employed hydrogen atom transfer (HAT).     

反胶束固定化醇脱氢酶的制备及应用研究

研究十六烷基三甲基溴化铵(CTAB)-辛烷-己醇反胶束体系固定化醇脱氢酶(ADH)的制备及应用。考察了含水量、CTAB和己醇用量对于ADH固定化的影响。对游离酶和固定化酶的催化动力学性质研究表明:酶促反应的最适pH值分别为8.2和8.8,最适温度分别为31℃和20℃,米氏常数分别为12mmol/L和7mmol/L。30℃时,游离酶存放150min后失活90%,固定化酶失活50%,表明反胶束固定化ADH有较好的热稳定性。应用此体系测定了试样中乙醇的含量。     

Selective oxidation of alcohols over nickel zirconium phosphate

Nickel zirconium phosphate nanoparticles were found to function as efficient catalysts for the selec-tive oxidation of a wide range of alcohols to their corresponding ketones and aldehydes using H2O2 as an oxidizing agent and without any organic solvents, phase transfer catalysts, or additives. The steric and electronic properties of various substrates had significant influence on the reaction con-ditions required to achieve acetylation. The results showed that this method can be applied for the chemoselective oxidation of benzyl alcohols in the presence of aliphatic alcohols. The catalyst used in the current study was characterized by ICP-OES, XRD, NH3-TPD, Py-FTIR, N2 adsorp-tion-desorption, SEM and TEM. These analyses revealed that the interlayer distance in the catalyst increased from 0.75 to 0.98 nm when Ni2+ was intercalated between the layers, whereas the crystal-linity of the material was reduced. The nanocatalyst could also be recovered and reused at least seven times without any discernible decrease in its catalytic activity. This new method for the oxi-dation of alcohols has several key advantages, including mild and environmentally friendly reaction conditions, short reaction time, excellent yields and a facile work-up.     

Analysis of ethyl glucuronide and ethyl sulfate using aqueous normal‐phase chromatography with mass spectrometry

The use of aqueous normal‐phase chromatography is explored as a possible format for the analysis of the forensically significant compounds ethyl glucuronide and ethyl sulfate. Standard solutions of the two compounds are used to verify the retention capabilities of two stationary phases (diamond hydride and undecanoic acid). These results are then compared to data obtained on hair extracts to determine if any matrix effects exist with respect to both retention and peak shape. The undecanoic stationary phase is used for the establishment of calibration curves for quantitative analysis. These curves are utilized to determine the concentration of ethyl glucuronide in several hair samples tested.     

Recent developments in oxidative biocatalytic cascades

Biocatalytic cascades that involve enzymatic oxidation as one or more key steps are powerful tools to access valuable chemicals with various functionalizations starting from simple substrates, without the isolation of intermediates. This review discusses the recent advances in oxidative cascades, with perspectives given on the current limitations and future developments. The strategies employed to achieve efficient supply of redox cofactors are also highlighted. The examples include cascades that begin with alkene epoxidation, alkane hydroxylation, alcohol oxidation or amine oxidation. These oxidative steps are followed by a variety of enzyme-catalyzed functionalizations, producing a diverse range of high-value products.     

Selective oxidation of alcohols with H2O2 catalyzed by zinc polyoxometalate immobilized on multi-wall carbon nanotubes modified with ionic liquid

In this work, acid functionalized multi-wall carbon nanotubes (MWCNTs) were modified with imidazolium-based ionic liquids. The selective oxidation of various alcohols with hydrogen peroxide catalyzed by[PZnMo₂W₉O₃₉]^5-, ZnPOM, supported on ionic liquids-modified with MWCNTs, MWCNTAPIB, is reported. This catalyst[ZnPOM@APIB-MWCNT], was characterized by X-ray diffraction, scanning electron microscopy (SEM) and FT-IR spectroscopic methods. This heterogeneous catalyst exhibited high stability and reusability in the oxidation reaction without loss of its catalytic performance.     

Reaction of 2-trifluoroacetyl-1,8-Bis(dimethylamino)naphthalene with strong organic bases: Deprotonation of 1-NMe2 group resulting in the formation of Benzo[g]indole derivatives versus nucleophilic addition to CO group

A novel approach to pyrrole ring closure in 2-trifluoroacetyl- and 2-ethoxycarbonyl-1,8-bis(dimethylamino)naphthalenes via treatment with 2-lithium-1,8-bis(dimethylamino)naphthalene producing the corresponding benzo[g]indole derivatives, was examined with different alkyl- and aryllithium compounds as well as with LDA. It was found that the highest yields of benzo[g]indoles (up to 70%) are obtained with aryllithium reagents when they contain NMe₂ group in ortho-position to the carbanionic centre. In all other cases the formation of acyclic alcohol arising from ordinary intermolecular addition of the carbanion to the CO group strongly prevails. The dramatic facilitation of deprotonation of the N-Me group in substrate followed by pyrrolic cyclization in the case of 2-lithium-N,N-dimethylanilines was explained through a specific structure of the reaction transition state.     

Efficient and green oxidation of alcohols with tert-butyl hydrogenperoxide catalyzed by a recyclable magnetic core-shell nanoparticle-supported oxo-vanadium ephedrine complex

A novel method for the oxidation of alcohols to the corresponding carbonyl compounds has been successfully developed using tert-butyl hydrogenperoxide (TBHP) in the presence of a catalytic amount of recyclable magnetic nanoparticle-supported oxo-vanadium ephedrine complex (VO(ephedrine)₂@MNPs) in PEG as a green solvent at 80 °C. The catalyst can be magnetically recycled and successfully reused in six subsequent reaction cycles with only slight decreases of its catalytic activity.