Bernard Besson

Catalytic activity of RhH(CO)(PPh3)3 in the presence of thiol: A new way of obtaining a very active species

Abstract Addition of the thiol t-BuSH to RhH(CO)(PPh 3 ) 3 either under nitrogen under ambient conditions or under CO/H 2 pressure under hydroformylation conditions generates the much more active dinuclear species Rh 2 (μ-S-t-Bu) 2 (CO) 2 (PPh 3 ) 2 .

Carboxylation of hydroxy aromatic compounds

Publisher Summary The carboxylation of hydroxyaromatic compounds in the form of alkaline salts (the Kolbe Schmitt reaction) is well known and applied in the synthesis of acids such as salicylic acid, para -hydroxybenzoic acid and ortho -cresotinic acid. Kolbe first produced salicylic acid by heating a mixture of phenol and sodium in the presence of carbon dioxide at atmospheric pressure. After that the importance of CO 2 pressure, temperature of the system and the role of water was highlighted.

Access to polychlorophenols: Chemistry of intermediates

Publisher Summary The development of an efficient analytical method enables to detect the presence of polychlorinated gem-dichlorocyclohexadienones in chlorination reaction masses. An in-depth study conducted on reactivity demonstrated that polychlorinated gem-dichlorocyclohexadienones had a very high degree of reactivity, but it explained how the mechanisms related to these compounds—which may have sometimes a catalytic quality—worked. All the products formed from polychlorinated gem-dichlorocyclohexadienones in the presence of chlorophenols are indeed those identified in the chlorination of phenol. These results confirm our hypothesis, and prove the essential role of polychlorinated gem-dichlorocyclohexadienones as reaction intermediates which can react to give either noble products (chlorinated phenols in meta), or unwanted condensation products (polychloro phenoxy phenols, polychloro dihydroxy biphenyls, etc.).