ISSN:
0268-2575
Keywords:
carbonylation
;
1-(4-isobutylphenyl)ethanol
;
ibuprofen
;
palladium
;
tppts
;
water soluble
;
two-phase
;
Chemistry
;
Biochemistry and Biotechnology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Process Engineering, Biotechnology, Nutrition Technology
Notes:
-1-(4-Isobutylphenyl)ethanol (IBPE) was carbonylated to 2-(4-isobutylphenyl)propionic acid (ibuprofen) in an aqueous/organic two phase system using the water-soluble Pd(tppts)3 catalyst [tppts = P(C6H4-m-SO3Na)3] in the presence of p-CH3C6H4SO3H at 363 K, 15 MPa CO pressure and a palladium concentration of 150 ppm without addition of organic solvents. Under these conditions the conversion of IBPE was 83% and the selectivity to ibuprofen 82% with no decomposition of the Pd(tppts)3 catalyst. Both the activity and selectivity were strongly influenced by the tppts/Pd molar ratio and the nature of the added Brønsted acid. Maximum efficiency was observed for P/Pd = 10. Acids of weakly or non-coordinating anions, such as p-CH3C6H4SO3H, CF3COOH or HPF6 afforded carbonylation. No catalytic activity was observed in the presence of acids of strongly coordinating anions, such as HI. The water-soluble Pd/dppps catalyst [dppps = Ar2-nPhnP-(CH2)3-PPhn′Ar2-n′; Ar = C6H4-m-SO3Na; n = nń = 0: 86% and n = 0, nń = 1: 14%] exhibited low catalytic activity and the major product obtained was the linear isomer of ibuprofen, 3-(4-isobutylphenyl)propionic acid (3-IPPA) with selectivities up to 78%. Replacement of tppts by a ligand containing less -SO3Na groups such as monosulphonated triphenylphosphine (tppms) gives rise to a dramatic drop in the catalytic activity and selectivity to ibuprofen. No catalytic activity was observed using palladium catalysts modified with 2-pyridyldiphenylphosphine (PyPPh2) and tris(2-pyridyl)phosphine (PPy3) which are both water soluble in their protonated form. A catalytic cycle is proposed to explain the observed results. ©1997 SCI
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
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