Catalytic homogeneous oxidation of monoterpenes and cyclooctene with hydrogen peroxide in the presence of sandwich-type tungstophosphates [M-4(H2O)(2)(PW9O34)(2)](n-) M = Co-II, Mn-II and Fe-III

authors	Santos, ICMS; Gamelas, JAF; Duarte, TAG; Simoes, MMQ; Neves, MGPMS; Cavaleiro, JAS; Cavaleiro, AMV
nationality	International
journal	JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
author keywords	Sandwich-type polyoxometalates; Monoterpenes; Cyclooctene; Oxidation
keywords	METAL-SUBSTITUTED POLYOXOTUNGSTATES; KEGGIN-TYPE POLYOXOTUNGSTATES; HIGH-VALENT MANGANESE; SELECTIVE OXIDATION; LIMONENE EPOXIDATION; COMPLEX HETEROPOLYTUNGSTATES; HETEROGENEOUS PERFORMANCE; CRYSTAL-STRUCTURE; ACTIVE CATALYSTS; ALKENE OXIDATION
abstract	Catalytic efficiency of tetrabutylammonium salts of sandwich tungstophosphates B-alpha-[M-4(H2O)(2)(PW9O34)(2)](n-), M = Co-II, Mn-II, Fe-III was studied in the oxidation of (R)-(+)-limonene, geraniol, linalool, linalyl acetate, carveol, and cis-cyclooctene with hydrogen peroxide, in acetonitrile. Oxidation of (R)-(+)-limonene gave limonene-1,2-diol as main product. Epoxidation of linalool takes place preferentially at the more substituted 6,7-double bond, the corresponding 6,7-epoxide reacting further, yielding furano- and pyrano-oxides, via intramolecular cyclization. Oxidation of linalyl acetate occurred preferentially at the more substituted 6,7-double bond for Mn-4(PW9)(2), affording 6,7-epoxide at 82% selectivity. Linalyl acetate 1,2-epoxide was the major product with 51% and 77% selectivity for Co-4(PW9)(2) and Fe-4(PW9)(2), respectively. Oxidation of carveol occurred with very good conversions in the presence of Mn-4(PW9)(2), Co-4(PW9)(2) and Fe-4(PW9)(2), yielding carvone and carveol 1,2-epoxide in similar amounts. Oxidation of cis-cyclooctene gave only the epoxide, while oxidation of geraniol at room temperature afforded 2,3-epoxygeraniol as the major product. (C) 2016 Elsevier B.V. All rights reserved.
publisher	ELSEVIER SCIENCE BV
issn	1381-1169
isbn	1873-314X
year published	2017
volume	426
beginning page	593
ending page	599
digital object identifier (doi)	10.1016/j.molcata.2016.10.021
web of science category	Chemistry, Physical
subject category	Chemistry
unique article identifier	WOS:000391075700038