Harold E. Swift

Dehydrodimerization of propylene using bismuth oxide as the oxidant

Abstract Bismuth oxide, Bi2O3, serves as an oxidant for the conversion of propylene to mainly 1,5-hexadiene. The main secondary product is benzene with small amounts of normal and cyclohexadiene also formed. The formation of 1,5-hexadiene most likely involves the combination of two allylic radicals. As the reaction temperature is increased from 475 to 500 °C, the yield of 1,5-hexadiene decreases while the benzene yield increases. To selectively produce 1,5-hexadiene from propylene, the reaction has to be carried out cyclically, where the propylene reacts with bismuth oxide for a given period of time, and then the oxygen that is consumed is rapidly replenished with air. If a sufficient amount of gas-phase oxygen is used with propylene, the bismuth oxide serves as a catalyst to give a continuous reaction.

Metallic phases and activities of nickel-tin-silica catalysts: Dehydrogenation of cyclohexanone, cyclohexanol, and cyclohexane

Abstract Addition of tin to a nickel-silica catalyst greatly promotes the activity and gives a longer catalyst life for the dehydrogenation of cyclohexanone and/or cyclohexanol to phenol. Outstanding results are obtained with a catalyst having a nickel-to-tin molar ratio of 2.5:1. Reduction of the nickel-to-tin molar ratio to 0.9:1 gives very little dehydrogenation of cyclohexanone; however, a new reaction takes place, which is the aldolization of cyclohexanone to 2-(1-cyclohexenyl)cyclohexanone. An explanation of the promoting effect of tin and the change in reaction selectivity with nickel-to-tin ratio is given. An investigation of the reduced nickel-tin-silica catalysts by X-ray diffraction has revealed the presence of a supported nickel-tin alloy phase.

Specific catalysis with iron coordination complexes

A novel three-component catalyst system has been found which is very active for the polymerization of isoprene. The catalyst consists of iron(III)acetyl-acetonate-triethylaluminum and specific bidentate ligands. The three bidentate ligands found which greatly promote the polymerization are in order of decreasing promoting ability: phenyl-2-pyridylacetonitrile, 2-cyanopyridine, and 2-pyridine-aldoxime. The ligand must contain certain functionalities to result in an active catalyst. The polymerization of isoprene proceeds best at low temperatures, such as −23 °C, and the rate and polymer yield decreases with increasing temperature. This unusual temperature effect is probably due to a greater catalyst stability at lower temperatures. This catalyst produces a polyisoprene which consists of approximately equal amounts of cis-1,4 and 3,4 linkages.

Preparation of cumene hydroperoxide

Cumene hydroperoxide is prepared by the oxidation of cumene with molecular oxygen in the presence of a minute amount of solid barium oxide.