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Epoxidation and catechol oxidation catalytic processes promoted by manganese(III) complexes of salen-type ligands

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Title Epoxidation and catechol oxidation catalytic processes promoted by manganese(III) complexes of salen-type ligands
 
Creator Guha, Averi
Zangrando, Ennio
Chandra, Arpita
 
Subject Mononuclear Manganese(III) complexes
Catecholase activity
Epoxidation catalyst
 
Description 169-176
Four new mononuclear manganese(III) complexes namely 1, 2, 3 and 4 of salen-type ligands H2L1-H2L4 (ligands were obtained in situ via Schiff-base condensation of 2-formyl-6-hydroxymethyl-4-methylphenol and amines cyclohexane-1,2-diamine, 2-methylpropane-1,2-diamine, propane-1,2-diamine and ethane-1,2-diamine, respectively) have been synthesised and characterised by routine physicochemical techniques. 1 is further characterised by X-ray single crystal structure analysis. Catalytic efficiencies of the complexes as epoxidation catalysts (substrates: styrene and (E)-stilbene; terminal oxidants: PhIO/NaOCl; solvent: MeCN /dicholorometane) and as catalysts for oxidation of catachol (substrates: 3,5-di-tert-butylcatechol (3,5-DTBC); solvent: methanol) have been evaluated. In both cases the catalytic efficiency increases on going from 4-1 although the actual mechanisms in those two catalytic reactions are completely different. However, the observations have been rationalized on the basis of steric and electronic factors exerted by the alkyl substituents present on the imine back-bone of the salen-type ligands. This study also verifies that there is at least another active epoxidizing species, [Cl–O–Mn(III)(salen)X] in addition to the discrete Mn(V)=O(salen) species in epoxidation of olefins depending upon the terminal oxidants employed.
 
Date 2021-02-11T07:06:47Z
2021-02-11T07:06:47Z
2021-02
 
Type Article
 
Identifier 0975-0975(Online); 0376-4710(Print)
http://nopr.niscair.res.in/handle/123456789/56205
 
Language en_US
 
Rights CC Attribution-Noncommercial-No Derivative Works 2.5 India
 
Publisher NISCAIR-CSIR, India
 
Source IJC-A Vol.60A(02) [February 2021]