Silicophosphoric acid

CgHi2 bicycloolefin isomerizations are summarized in Fig. 2. At 260°, over a silicophosphoric acid catalyst, bicyclo[2.2.2]-2-octene (4) is converted to the bicyclo[3.3.0]-2-octene (6), with intermediate formation of bicyclo[3.2.1]-2-octene (5). The yield of hydrocarbon 5 passes through a maximum and then vanishes when the conversion of 4 increases 8-10, 18a). This isomerization also slowly forms a mixture... 

Knotnerus and Schilling (22) have recently reinvestigated these reactions at 260-280° in the presence of the silicophosphoric and silica-alumina acid catalysts. Typical yields in the isomerization of 9 (silicophosphoric acid catalyst, HLSV = 0.25 hr-i) are shown in the tabulation. These figures are based on the hydrocarbon injected (40%... 

Finally, the cycloisomerization of 4-vinylcyclohexene (a butadiene dimer) to bicyclo[3.3.0]-2-octene (6) was found to occur at 250° over a silicophosphoric acid catalyst (11), along with a very large amount of hydrogen transfer (ethylcyclohexenes, methylethylcyclopentenes, ethylbenzene) and polymerization, a reaction closely related to that of limonene (5). A much better yield of the same hydrocarbon (6) was obtained from 1,5-cyclooctadiene (72% at 200°) with the same catalyst (25). 

In this series we may find, besides the methylated homologs of the C8Hi2 hydrocarbons already described, some new products of cycle expansion. The vapor-phase silicophosphoric acid-catalyzed reaction of 2-methylenebicyclo[2.2.2]octane (18) at 195° produces the double-bond isomer (1 ) and a mixture of 1-methyl-, 2-methyl-, and 3-methylbicyclo-3.2.1[octenes] (21, 22, and 23) (Fig. 5) through seemingly parallel reactions (Fig. 6) 15, 16). 

Fio. S. Isomerization of 2-methylenebicyclo[2.2.2]octane (18) at 196-250°, vapor phase, in the presence of silicophosphoric acid catalyst. 

When passed over the silicophosphoric acid catalyst at 250 , this mixture is readily converted to 24, 25, and 26, as expected. Apparently,... 

The remarkably consistent pattern outlined in the reactions of the CgHi2 and C9H14 series should also appear in the CioHie series, and in particular, for bicyclic terpenes. Camphene (37) (Fig. 12), closely related to isosantene (27), was reacted at 250° in the vapor phase in the presence of silicophosphoric acid catalyst (18). A rather complicated monomer fraction (30 chromatographic peaks), steam-distilled from... 

Fig. 13. Composition of isomer mixture (mole %) versus contact time (wt catalyst/wt of hydrocarbon injected per hour) in the reaction of camphene at 250°, vapor phase, in the presence of silicophosphoric acid catalyst. I, Camphene 2, dimethylbicyclo-[3.2.1]-3-octene 3, a-terpinene 4, p-cymene 5, dimethylbicyclo[3.3.0]-2-octene 6, dimethylethylbenzenes 7, tetramethylbenzenes 8, methylhexahydroindenes 9, methylindan.

His first major discovery in the U.S. was the development of silicophosphoric acid (solid phosphoric acid) as a catalyst for hydrocarbon conversion. 

Silicophosphoric acid was also used in copolymerization of butenes, which, followed by hydrogenation, yielded high-octane components for gasoline. 

Colloids of silicophosphoric acid derivatives have not been further investigated, but silicon phosphates have been studied. Jacoby (172) found that at atmospheric pressure, melts of SiO, and P,0, could be made in which 21 compounds were detected. Physical properties of SiO,-P,Oj and 3SiO, 2P,Os were reported. Dissolu tion of some compounds of this type in water or alcohols would probably give aqueous dispersions of colloidal silica, or mixed acid esters similar to that described above. 

Silicon dioxide 16, 101, 938 Silicone oil as antifoam agent 13, 116 15,122 18, 213 Silicophosphoric acid ester chains... 

The hydration of oleflns is important for the direct synthesis of alcohols from olefins in the pietroleum industry and has been extensively studied over various solid acid catalysts. In the case of ethanol synthesis from ethylene and water, silicotungstic acids, silicophosphoric acids, solid phosphoric acids, metal sulfates, " and metal oxides have been studied as solid acid catalysts. In its industrial process, a solid phosphoric acid catalyst (Shell patent) is widely used throughout the world. The nature of the active (acidic) sites which exhibit high catalytic activity and selectivity is discussed below together with the hydration mechanism involving the catalytic behavior. 

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