Influence of solution ionic strength on aggregation of novel water soluble phosphines and two phase catalysis

The preparation of new water soluble phosphines for organometallic chemistry and catalysis in water is important to the development of environmentally benign homogeneous catalysts. A series of steric demanding surface active phosphines have been synthesized and fully characterized. Two phase hydroformylation of 1-hexene and 1-octene with rhodium complexes of these water soluble phosphines has been investigated. The results indicate that both reaction activity and selectivity for these water insoluble olefins are significantly better than the rhodium/TPPTS system which is used commercially for hydroformylation of propene. Quantitative measurement of the aggregation of these surface active phosphines has been done. It is proposed that rate and selectivity enhancements are due, in part, to the aggregation of the ligand. Ionic water soluble phosphines and their metal complexes are strong electrolytes. Salt addition for various purposes is a common technique in the aqueous phase chemistry. In the case of water soluble catalysis, the solution ionic strength may be expected to influence the stability of catalytic intermediates which in turn could have a decisive influence on the catalytic activity and selectivity. Reported here is the first study that systematically investigates the effect of ionic strength on aqueous phase catalysis. The study provides the basic understanding of the relationship between solution ionic strength and hydroformylation rate and selectivity in the aqueous phase. The organometallic chemistry and catalysis with water soluble bis-diphenyl phosphine-chelates have been fully investigated. But the preparation of this class of ligands suffers from low yield and uncertainty of the site of sulfonation. Introduction of α-ω diphenylalkyl group into a chelating phosphine via LiP[C₆H₄(CH₂)ₓC₆H₅]₂ results in a new class of chiral chelating phosphines which can be easily sulfonated. This highly efficient, well defined sulfonation method leads to surface active phosphines which are sterically and electronically similar to those bis-diphenyl phosphine-chelates. (S₁ S) tetrasulfonated 2,4-bis-diarylphosphinopentane has been successfully synthesized and its applications in aqueous phase hydrogenation shows improved reaction rate and enantioselectivity compared to its non-surface active analogs.

Name thesis:degree_name

Ph. D.

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

Chemistry

Department dc:contributor.department

Chemistry

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

1995

Author dc:creator

• Ding, Hao

Chair dc:contributor.committeechair

• Hanson, Brian E.

Committee members dc:contributor.committeemember

• Merola, Joseph S.
• Brewer, Karen J.
• Dillard, John G.
• Glanville, James O.

• chemical interaction

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

en

Dc Identifier Other

etd-10042006-143900

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/39609