Wael Baidossi

Effect of the CO2H groups of carboxylated triarylphosphines on (COD) RhCl(PAr3)-catalyzed isomerization of 1-octen-3-ol under phase transfer conditions

Abstract Water soluble sodium salts of (COD)RhCl(PAr3), where PAr3 is Ph2P(C6H4-2-COOH), Ph2P(C6H4-3-COOH), Ph2P(C6H4-4-COOH), PhP(C6H4-3-COOH)2, or P(C6H4-3-COOH)3, catalyze under phase transfer conditions the isomerization of 1-octen-3-ol to 3-octanone. The reaction rate depends on the position and number of the carboxyl groups in the phosphine ligand. (COD)RhCl[Ph2P(C6H4-2-C6H4COOH], which exists as an equilibrium mixture with (COD)(H)R hCl(-OCOC 6 H 4 -2-P Ph2) is more reactive than the hydride-free catalysts. A hydride addition-elimination mechanism is suggested as the major pathway for the catalytic process.

Homogeneous and biphasic oligomerization of terminal alkynes by some water soluble rhodium catalysts

Abstract The catalytic activity of six water soluble rhodium compounds, RhCl3·3H2O 1, RhCl(Ph2PC6H4-3-SO3Na)3·4H2O 2, (COD)RhCl(Ph2PC6H4-3-SO3Na)·H2O 3, [(COD)Rh(μ-Ph2PC6H4-3-SO2-O)]24, [(CO)Rh(Ph2PC6H4-3-CO2H)(μ-SPh)]25, and [Rh3O(OAc)6-(H2O)3]OAc 6, for oligomerization of model hydrophilic and lipophilic terminal alkynes was investigated under homogeneous and under biphasic conditions. While propynoic acid 7 is converted by all six catalysts solely into trimellitic acid, 8, and trimesic acid, 9, phenylacetylenes 10 either dimerize, trimerize or give stereoregular polymers. The nature of the oligomerization products proved to depend on the catalyst, the medium and the reaction temperature. In acetonitrile, complex 4 transforms the various phenylacetylenes (except 4-nitrophenylacetylene, 10f) mainly or entirely to the head-to-tail dimers, 13, which undergo thermal rearrangement to the head-to-head isomers, 14.

A convenient route to 1,3,5-trisubstituted benzenes via rhodium catalyzed polymerization of arylacetylenes

Abstract [(1,2,5,6-η)-1,5-Cyclooctadiene] (1,3-propanediamine-N,N′)rhodium(1+) chloride, [(COD)RhCl(H2NCH2CH2CH2NH2)]Cl, 11, and the water soluble complexes (COD)RhCl(Ph2PC6H4-3-SO3Na) 10, trans-[Rh(CO) (Ph2PC6H4-3-CO2H) (μ- NCMeCHCMeN )]2 12, (Ph2PC6H4-2-CO-O)-Rh(CO) ( NHMeCHCMeN ) 13a, (Ph2PC6H4-2-CO-O)-Rh(CO) (indazole) 13b and trans-[Rh(CO) (Ph2PC6H4-2-CHO) (μ- NCMeCHCMeN )]2 14 were shown to catalyze the polymerization of PhCCH 1 and the substituted arylacetylenes 2–8 at 25°C in a stereoregular manner. The cis-oriented poly(arylacetylenes), so formed, were found to depolymerize selectively at 200–225°C to the corresponding 1,3,5-triarylbenzene derivatives.

Selective transformations of phenylated diynes to polycyclic compounds by the RhCl3- and PtCl4-Aliquat 336® ion pair catalysts

Abstract The ion pairs generated from methyltricaprylammonium chloride and either RhCl 3 or PtCl 4 catalyze, under phase transfer conditions, selective cyclore-arrangements, as well as intra- and intermolecular addition processes by which discrete polycyclic compounds are formed. The nature of the products depends on the distances between the ethynyl functions and on the catalyst employed.

The presence of KCl in the exposure medium strongly influences the mutagenicity of metabolites of polycyclic aromatic hydrocarbons in Escherichia coli

Previous studies demonstrated that the ion composition of the exposure medium may strongly influence the mutagenicity of many compounds in the liquid preincubation modification of the reversion assay with his- Salmonella typhimurium strains. Similar influences were now observed in the reversion assay with trp- Escherichia coli strain WP2 uvrA. The exposure medium was 8 mM sodium phosphate buffer (pH 7.4), containing no other ions or 125 mM KCl. Omission of KCl resulted in an about 10-fold enhancement of the mutagenic activity of 7-methylbenz[a]anthracene 5,6-oxide, but in a strong decrease in the mutagenicity of 1-hydroxymethylpyrene sulphate, close to the limit of detection. The findings with these two representative mutagens are very similar to those previously observed in S. typhimurium, suggesting that unobtrusive medium components may exert strong influences on the results with many test compounds in various bacterial test systems.