Volume 35, Issue 12 e6437
RESEARCH ARTICLE

Solvent-free oxidation of straight-chain aliphatic primary alcohols by polymer-grafted vanadium complexes

Payal Kachhap

Payal Kachhap

Department of Chemistry, Indian Institute of Technology (Indian School of Mines), Dhanbad, India

Contribution: Data curation (lead), ​Investigation (lead), Validation (equal), Visualization (equal)

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Nikita Chaudhary

Nikita Chaudhary

Department of Chemistry, Indian Institute of Technology (Indian School of Mines), Dhanbad, India

Contribution: Conceptualization (supporting), Formal analysis (supporting), Methodology (supporting), Project administration (supporting), Supervision (supporting)

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Chanchal Haldar

Corresponding Author

Chanchal Haldar

Department of Chemistry, Indian Institute of Technology (Indian School of Mines), Dhanbad, India

Correspondence

Chanchal Haldar, Department of Chemistry, Indian Institute of Technology (Indian School of Mines), Dhanbad 826004, Jharkhand, India.

Email: [email protected]

Contribution: Conceptualization (lead), Data curation (supporting), Formal analysis (lead), Funding acquisition (lead), ​Investigation (supporting), Methodology (lead), Project administration (lead), Resources (lead), Software (lead), Supervision (lead), Validation (equal), Visualization (equal)

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First published: 07 September 2021
Citations: 3

Funding information: Government of India, New Delhi, Grant/Award Number: SB/EMEQ-055/2014

Abstract

Oxidovanadium(IV) complexes [VO(tertacac)2] (1), [VO(dipd)2] (2), and [VO(phbd)2] (3) were synthesized by reacting [VO(acac)2] with 2,2,6,6-tetramethyl-3,5-hepatanedione, 1,3-diphenyl-1,3-propanedione, and 1-phenyl-1,3-butanedione, respectively. Imidazole-modified Merrifield resin was used for the heterogenization of complexes 1–3. During the process of heterogenization, the V4+ center in complex 2 converts into V5+, whereas the other two complexes 1 and 3 remain in the oxidovanadium(IV) state in the polymer matrix. Theoretically, calculated IPA values of 1–3 suggest that 2 is prone to oxidation compared with 1 and 3, which was also supported by the absence of EPR lines in 5. Polymer-supported complexes Ps-Im-[VIVO(tertacac)2] (4), Ps-Im-[VVO2(dipd)2] (5), and Ps-Im-[VIVO(phbd)2] (6) were applied for the solvent-free heterogenous oxidation of a series of straight-chain aliphatic alcohols in the presence of H2O2 at 60°C and showed excellent substrate conversion specially for the alcohols with fewer carbon atoms. Higher reaction temperature improves the substrate conversion significantly for the alcohols containing more carbon atoms such as 1-pentanol, 1-hexanol, and 1-heptanol while using optimized reaction conditions. However, alcohols with fewer carbon atoms seem less affected by reaction temperatures higher than the optimized temperature. A decreasing trend in the selectivity(%) of carboxylic acid was observed with increasing carbon atoms among the examined alcohols, whereas the selectivity towards aldehydes increased. The order of efficiency of the supported catalysts is 4 > 6 > 5 in terms of turnover frequency (TOF) values and substrate conversion, further supported by theoretical calculations.

CONFLICT OF INTEREST

There are no conflicts of interest to declare.

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