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A thermally stable solid acid catalyst has been prepared by treating amorphous silica gel with trifluoromethanesulphonic (triflic) acid (TFA) at 150°C in a closed glass vessel. A solvent such as 1,1,2-trichloro-2,2,1-trifluoro-ethane (Freon 113) can be conveniently used to dissolve TFA. The obtained material is an active catalyst in the alkylation of isobutane with n-butenes to yield high-octane gasoline components. In the reaction it behaves like a truly solid catalyst not leaching TFA in the solution for about 24 h. The catalyst characterisation has been performed by 1H- and 19F-NMR and IR spectroscopy.

Solid acid catalysts based on heteropoly acids supported on different oxides catalyse the alkylation of isobutane with n-butenes to yield high‐octane gasoline components. They are active for a short period of time on stream. Regeneration is easily made by thermal treatment under air. The catalysts have been characterised by NMR, EPR, XRD and TEM‐EDS techniques.

The main achievements and future prospects of in situ oxidations are discussed, focusing on the advantages and limits of the technique. This is based on hydrogen peroxide, peracids, metal peroxo and metal oxo species, generated in situ by oxygen and a reducing agent: hydrogen, carbon monoxide, metallic iron or zinc, hydrides, aldehydes and other organic reductants. Hydrogen peroxide and hydrogen, respectively, are preferred reagents for the inherent cleanliness of their use, producing only water as the byproduct. Examples are the epoxidation of propylene by air and alkylated anthrahydroquinones, catalysed by titanium silicalite (TS-1), and the hydroxylation of alkanes and aromatics on TS-1 and on other heterogeneous catalysts loaded with noble metals. The halogenation of phenol with hydrogen/oxygen/halogenidric acid mixtures on Pd/TS-1, has also been reported. Carbon monoxide was used to replace hydrogen in in situ oxidations occurring at higher temperatures. Reducing agents other than hydrogen and carbon monoxide lead to the formation of more than stoichiometric amounts of coproducts, which add complexity to the overall process for their separation and recycle/disposal. In the in situ oxidations by GifIII/IV systems and by aldehyde/oxygen mixtures, large amounts of metallic wastes and carboxylic acid are co-produced, respectively, hindering their application in bulk chemicals production. Future developments might arise from the design of superior catalysts both for the in situ generation of hydrogen peroxide or peroxidic species from oxygen/hydrogen mixtures and for its subsequent efficient use. Oxygen/carbon monoxide and nitrous oxide can replace hydrogen/oxygen in oxidations at progressively higher temperatures, albeit no in situ oxidation with N2O as yet has been reported. The general features of hydrogen peroxide and nitrous oxide are briefly compared and discussed.

Possible mechanisms for the silylformylation of 1-alkynes catalyzed by Rh2Co2(CO)12 are investigated. Novel Rh-Co mixed metal complexes, (PhMe2Si)2Rh(CO)nCo(CO)4 (n = 2 or 3) (3) and RhCo(HC≡CBun)(CO)5 (5), are found to play important roles in this catalysis. The reaction of 3 with 1-hexyne and HSiMe2Ph at ambient temperature and pressure of CO gives n-BuC(CHO)=CHSiMe2Ph (1a, Z/E = 95/5), (PhMe2Si)2Rh(CO)3Co(CO)4 (3-B) and an Rh-Co mixed metal butterfly complex, h2Co2(HC≡CBun)(CO)10 (4). The reaction of 5 with 1-hexyne and HSiMe2Ph under the same ambient conditions affords 1a (100% Z) very cleanly as the sole reaction product. The crossover experiments u sing RhCo(DC≡CBun)(CO)5(5-d), 1-hexyne-1d and DSiMe2Ph strongly support the mixed metal bimetallic catalysis and involvement of bis(alkyne)-Rh-Co species. The most plausible catalytic cycle of silylformylation which can accommodate all the observed results is proposed.

The reactions of hydrosilane and/or alkyne as well as isonitriles with rhodium and rhodium cobalt mixed metal carbonyl clusters, e.g., Rh4(CO)12 and Co2Rh2(CO)12, are studied. Novel mixed metal complexes, e.g., CoRh(CO)5 (HC≡CBu n ), (R3Si)2Rh(CO) n Co(CO)4, Rh(R−N≡C)4Co(CO)4, Co2Rh2(CO)10(HC≡CR), and Co2Rh2(CO)9(HC≡CBu n ), are synthesized and identified. The catalytic activities of these rhodium and rhodium-cobalt mixed metal complexes are examined in hydrosilyation, silylformylation, and novel silylcarbocyclization reactions. Possible mechanisms for these reactions are proposed and discussed.

Reactions of hydrosilanes with 1-hexyne catalyzed by Co 2 Rh 2 (CO) 12 and Rh 4 (CO) 12 at 25 o C and atmospheric pressure-150 psi of carbon monoxide give (Z)-1-silyl-2-formyl-1-hexenes, which are the products of «silylformylation», and/or (E)-1-silyl-1-hexenes