Selective and controlled aerobic oxidation of activated benzyl alcohols to the corresponding aldehydes is achieved in refluxing CH3CN using catalytic amounts of MoO2Cl2(L)2 where L is DMSO, DMF or THF. The catalysis reactions are possible under open air in the absence of any other external co-oxidants. However, bubbling of oxygen to the reaction mixture is useful in making the catalysis reaction sustained. Both activated and deactivated varieties of α-substituted benzyl alcohols (secondary alcohols) give ketones in the same reaction conditions. The inexpensive catalyst is selective towards activated primary benzyl alcohols and also, being mild, stops the oxidation at the aldehyde stage, making it synthetically useful. Copyright © 2006 John Wiley &amp; Sons, Ltd.

Dillip Kumar Chand

Department Of Chemistry

Kandasamy Jeyakumar

alcohols

Aldehydes

catalysis

Ketones

Organometallics

oxidation

Substitution reactions

Benzyl Alcohols

CO-OXIDANTS

DEACTIVATED VARIETIES

Homogeneous catalysis

Molybdenum compounds

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

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IIT Madras

Applied Organometallic Chemistry

A surfactant based oxodiperoxo molybdenum complex, which could activate molecular oxygen, has been employed as a catalyst for controlled oxidation of benzylic alcohols to corresponding carbonyls. The oxidation reactions were carried out under aqueous environment, however, in the absence of any extraneous base or co-catalyst. Sensitive/oxidizable functional groups like cyano, sulfide, hydroxyl, aryl-hydroxyl, alkene (internal/terminal), alkyne (internal/terminal), and acetal were tolerated during the transformations. Such selectivity is attributed to the mild nature of the catalyst. The methodology could also be scaled-up for multi-gram synthesis and the protocol is likely to find practical use since it requires an inexpensive recyclable-catalyst and easily available oxidant (under green conditions). A plausible mechanism is proposed with the help of preliminary computational study. © 2019 Elsevier Inc.

Journal of Catalysis

A molybdenum based metallomicellar catalyst for controlled and chemoselective oxidation of activated alcohols in aqueous medium

A variety of aromatic, aliphatic and conjugated aldehydes and alcohols were transformed to the corresponding carboxylic acids and ketones with a quantitative conversion in high yields with 70% t-BuOOH solution in water in the presence of catalytic amounts of ceric ammonium nitrate [Ce(NH 4)2(NO3)6] (CAN) under room temperature conditions. The scope of our catalytic system is applicable for a wide range of aromatic, conjugated and aliphatic substrates. These aldehydes were converted to the corresponding carboxylic acids in good isolated yields in reasonable times. This method possesses a wide range of capabilities since it can be used with other functional groups which may not tolerate oxidative conditions, involves fairly simple method for work-up, exhibits chemoselectivity and proceeds under ambient conditions. The resulting products are obtained in good yields within reasonable time. © 2011 SIOC, CAS, Shanghai &amp; WILEY-VCH Verlag GmbH &amp; Co. KGaA, Weinheim.

Chinese Journal of Chemistry

Ceric ammonium nitrate catalyzed oxidation of aldehydes and alcohols

A variety of aromatic, aliphatic and conjugated aldehydes and alcohols were transformed to the corresponding carboxylic acids and ketones with a quantitative conversion in high yields with 70% t-BuOOH solution in water in the presence of catalytic (5 mol%) amounts of CuBr2 under room temperature conditions. The conversion of 4-methoxybenzaldehyde to 4-methoxybenzoic acid is extremely facile in MeCN at ambient temperature in the presence of 5 mol% CuBr2 and 2 equiv. 70% t-BuOOH (water) as the oxidant. Oxidation with t-BuOOH (water) alone in MeCN was found to be negligible. The scope of our catalytic system is applicable for a wide range of aromatic, conjugated and aliphatic substrates. These aldehydes were converted to the corresponding carboxylic acids in good isolated yields in reasonable times. It is pertinent to mention here that mild halogenic oxidants like hypochlorites, chlorites and NBS are not suitable for substrates with electron-rich aromatic rings, olefinic bonds and secondary hydroxyl groups. Substitutions at different positions on the phenyl ring do not hinder the reaction, although the reaction time is affected. Oxidation of α,β unsaturated derivatives resulted in the formation of the expected acid in good yield. In addition, the transformation of secondary alcohols to ketones is extremely facile. No recemization was observed for menthone. This method possesses a wide range of capabilities since it can be used with other functional groups which may not tolerate oxidative conditions, involves fairly simple method for work-up, exhibits chemoselectivity and proceeds under ambient conditions. The resulting products are obtained in good yields within reasonable time. © 2011 John Wiley &amp; Sons, Ltd.

Cu(II) bromide catalyzed oxidation of aldehydes and alcohols

The role of MoO2Cl2 and some complexes containing MoO2Cl2 as catalysts for various Lewis acid catalysed organic transformations, oxidation and reduction reactions is reviewed. © Indian Academy of Sciences.

Fulltext

Journal of Chemical Sciences

Application of molybdenum(VI) dichloride dioxide (MoO2Cl 2) in organic transformations

Synthesis of β-keto esters by condensing various aldehydes with ethyl diazoacetate is achieved by using molybdenum(VI) dichloride dioxide. Aromatic, aliphatic, and heterocyclic aldehydes are successfully condensed with ethyl diazoacetate to obtain corresponding β-keto esters in high yields at room temperature.

Synthesis

Molybdenum(VI) dichloride dioxide catalyzed synthesis of β-keto esters by C-H insertion of ethyl diazoacetate into aldehydes

Selective oxidation of sulfides to sulfoxides and sulfones is achieved by H2O2 using MoO2Cl2 as the catalyst. Various substituted sulfides having functional groups such as methyl, methoxy, bromo, nitro, alkene, alkyne, alcohol, ester, aldehyde and remarkably an oxime are successfully and selectively oxidized without affecting the sensitive functionalities. © 2006 Elsevier Ltd. All rights reserved.

Tetrahedron Letters

Selective oxidation of sulfides to sulfoxides and sulfones at room temperature using H2O2 and a Mo(VI) salt as catalyst

ChemInform

ChemInform Abstract: Oxidations in Organic Chemistry

A novel method for the reduction of imines using the system silane/MoO2Cl2

The Journal of Organic Chemistry

Nucleophilic Acyl Substitutions of Anhydrides with Protic Nucleophiles Catalyzed by Amphoteric, Oxomolybdenum Species

Inorganic Chemistry Communications

Oxoperoxo-molybdenum and -tungsten (VI) complexes: their synthesis, structure and catalytic uses in the peroxidic oxidation of alcohols to aldehydes and ketones

Aerobic oxidation of benzyl alcohols by MoVI compounds

Journal	Applied Organometallic Chemistry
ISSN	02682605
Open Access	No