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Electronically dissymetric DIPHOS derivatives give higher n:i regioselectivity in rhodium-catalyzed hydroformylation than either of their symmetric counterparts

Journal Article · · Journal of the American Chemical Society
DOI:https://doi.org/10.1021/ja982117h· OSTI ID:20014094
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Electronic effects on rhodium-catalyzed hydroformylation of 1-hexene with electronically dissymmetric DIPHOS derivatives [3,5-(CF{sub 3}){sub 2}C{sub 6}H{sub 3}]{sub 2}PCH{sub 2}CH{sub 2}PPH{sub 2} = [DIPHOS-(3,5-CF{sub 3},H)] (1), [2-(CF{sub 3})C{sub 6}H{sub 4}]{sub 2}PCH{sub 2}CH{sub 2}PPh{sub 2} = [DIPHOS-(2-CF{sub 3}H)] (2), [3,5-(CF{sub 3}){sub 2}C{sub 6}H{sub 3}]{sub 2}PCH{sub 2}CH{sub 2}P[2-(CH{sub 3})C{sub 6}H{sub 4}]{sub 2} = [DIPHOS-(3,5-CF{sub 3}2-CH{sub 3})] (3), and [2-(CF{sub 3})C{sub 6}H{sub 4}]{sub 2}PCH{sub 2}CH{sub 2}P[2-(CH{sub 3})C{sub 6}H{sub 4}]{sub 2} = [DIPHOS-(2-CF{sub 3},2-CH{sub 3})] (4) were investigated. Two apical-equatorial chelate isomers were observed for model (diphosphine)Ir(CO){sub 2}H complexes of dissymmetric diphosphines 1--4. In each case, the equatorial phosphine of the major isomer (96--60%) had electron-withdrawing aryl substituents. These dissymmetric DIPHOS derivatives were used to test the hypothesis that an electron-withdrawing substituent on an equatorial phosphine increases the hydroformylation n:i ratio while an electron-withdrawing substituent on an apical phosphine decreases the n:i ratio. In agreement with the predictions of this hypothesis, hydroformylation with the dissymmetric diphosphine ligand DIPHOS-(3,5-CF{sub 3},H) (1), gave an n:i ratio of 4.2:1, higher than either of the symmetric ligands DIPHOS, 2.6:1, and DIPHOS-(3,5-CF{sub 3}), 1.3:1. Similar observations were made for hydroformylations with 2--4.

Research Organization:
Univ. of Wisconsin, Madison, WI (US)
Sponsoring Organization:
US Department of Energy
OSTI ID:
20014094
Journal Information:
Journal of the American Chemical Society, Journal Name: Journal of the American Chemical Society Journal Issue: 1 Vol. 121; ISSN JACSAT; ISSN 0002-7863
Country of Publication:
United States
Language:
English

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Related Subjects

40 CHEMISTRY
CARBONYLATION
CATALYSTS
DERIVATIZATION
HEXENES
PHOSPHINES
RHODIUM
SYMMETRY