The reaction mechanism of the Kolbe-Schmitt reaction of phenol and 2-naphthol has been investigated. An alkali metal phenoxide-CO2 complex is not an intermediate that can be easily transformed into a carboxylic acid, such as salicylic acid (SA) and p-hydroxybenzoic acid (pHBA). A direct carboxylation of phenoxide with CO2 takes place even at room temperature, and is competitive with the formation of the CO2 complex. The resulting complex decomposes thermally (above ca. 100 degrees C) to phenoxide, which then undergoes further competitive reactions. Experiments using a carbon-13 labeled complex support a mechanism of direct carboxylation, and not the mechanism via a CO2 complex. The reactivity, C-13 NMR and MOPAC/PM3 calculations suggest a new carbonate-like structure for the CO2 complex.
The silylcobalt complexes [R2R′SiCo(CO)4] (R, R′ = Ph, Me) reacted with dinitrogen complexes of the type [M(N2)2(P)4] (M = Mo, W; P = tertiary phosphine) to give new silyldiazenido complexes trans-[M(NNSiR2R′)(P)4][(μ-OC)Co(CO)3], which were further converted to silylhydrazido(2−) complexes such as trans-[WX(NNHSiR2R′)(dpe)2][Co(CO)4] by treatment with HX (dpe = Ph2PCH2CH2PPh2; X = OH, OMe, Br).
Preparation and Properties of Molybdenum and Tungsten Dinitrogen Complexes. Part 31. Silylation of Coordinated Dinitrogen by Silylcobalt Complexes. Preparation of a New Series of Silyldiazenido and Silylhydrazido(2-) Complexes of Molybdenum and Tungsten. --(STREET, A. C.; MIZOBE, Y.; GOTOH, F.; MEGA, I.; OSHITA, H.; HIDAI, M.; Chem. Lett. (1991) 3, 383-386; Dep. Synth. Chem., Univ. Tokyo, Hongo, Tokyo 113, Japan; EN)
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