Robert L. Banks

Specialty chemicals via olefin metathesis

Abstract A wide variety of specialty chemicals are now available from technology based on the olefin metathesis reaction. This versatile reaction allows the conversion of simple, relatively inexpensive olefins into specialty, high-purity olefins which are useful intermediates in the fragrance, agricultural, and many other specialty chemical industries. In addition to originating the technology for the first commercial application of olefin methathesis (the Triolefin Process for converting propylene into high-purity ethylene and butenes), Phillips Petroleum Company R & D has been active in developing the technology for the preparation of many specialty olefins. Neohexene, an intermediate in the synthesis of musk perfume, is produced commercially in a plant completed in 1980; the reaction involves cometathesis of diisobutylene with ethylene. Developmental quantities of α,- ω-diolefins, intermediates in the preparation of agricultural chemicals, are synthesized by the reaction of ethylene with selected cyclic olefins. Alpha olefins and isomerically pure internal olefins are readily produced via olefin metathesis chemistry. The development of a new class of catalysts allows the methathesis of certain functional olefins. Olefin metathesis is being established as a valuable synthetic tool which is providing increasing access to numerous specialty chemical markets.

Olefin metathesis catalyst

Olefins are converted into other olefins having different numbers of carbon atoms by contact with a catalyst comprising an inorganic refractory oxide support containing at least one of tungsten oxide and molybdenum oxide and a promoting amount of at least one methylating agent under conditions suitable for the methylating agent compounds to promote the activity of tungsten and molybdenum oxides for the disproportionation reaction.Abstract Model supports consisting of a thin layer of SiO2 on a Silicon single crystal have been used to study the [W]n+/SiO2/Si (100) model catalyst precursor prepared by a controlled reaction of π-C5H5W(CO)3Cl with the SiO2 surface. Characterization of the tungsten surface species has been performed by combination of conventional, angle-resolved and depth-profiling X-ray photoelectron spectroscopy (XPS). The silica surface consists of highly dispersed W-oxide units linked by two Si–O–W bonds. Further, compared with the powder analogues, a drastic increase in spectral resolution and detailed band structure is observed in the XPS spectra.

New developments and concepts in enhancing activities of heterogeneous metathesis catalysts

Abstract Our continuing investigations of heterogeneous metathesis catalysts have led to three findings: (1) Studies of MgO/WO 3 ·SiO 2 combinations suggest that MgO plays an unexpected beneficial role in olefin metathesis catalysis: that of generating gas-phase ‘excited species’ ( e.g. allyl or allyl-oxo radicals), which are initiators or precursors of metathesis sites, producing dramatic increases in metathesis activities. The proposed new concept is indirectly supported by findings that the activities of MoO 3 metathesis catalysts are not likewise enhanced by MgO; more significantly, enhancement of WO 3 catalysts does not occur when MoO 3 , a radical scavenger, is present. (2) The catalytic activities of conventional heterogeneous metathesis catalysts are increased significantly by admixing minor amounts of elemental S, Si, Mg, Ba, Sn, Zn, Sb or W with the metathesis catalysts, and treating the admixtures at elevated temperature under an inert atmosphere. The enhanced activity is attributed to a partial reduction of the catalysts by the added reducing metals or elements. (3) An unusual and interesting catalytic behavior is exhibited by rhenium oxide supported on Th 3 (PO 4 ) 4 : the metathesis activity increased by more than 50% when small amounts of oxygen were added to the olefin feed. Other heterogeneous metathesis catalysts, including Re 2 O 7 ·Al 2 O 3 and Re 2 O 7 ·AlPO 4 , do not show this behavior when oxygen is added; in most cases, traces of oxygen produce a decline in metathesis activity. This unusual behavior has fundamental implications: key roles for oxygen ligands have been claimed for both homogeneous and heterogeneous metathesis catalysts.

Industrial aspects of the disproportionation reaction

Abstract Olefin disproportionation provides a versatile and novel route for the commercial interconversion of all types of olefins. Its initial industrial application was the production of high-purity ethylene and butenes from propylene. Technology has been developed for the production of long-chain linear olefin products as precursors of synthetic lubricants, plasticizer alcohols, and a variety of surfactant preparations. Isoamylene, an intermediate in polyisoprene synthesis, is obtained by the cross-disproportionation of isobutylene with propylene or 2-butene. Neohexene, used in the synthesis of perfume musk, is produced in commercial quantities by cleaving diisobutylene with ethylene. In the area of specialty petrochemicals, potential industrial applications include the preparation of terminal olefins and diolefins, and olefins containing functional groups. High selectivity and conversion can be achieved by proper feed purification and the selection of a suitable catalyst and process conditions. The commercial future of olefin disproportionation technology is highly sensitive to the relative cost of feedstocks and products. At present, the economics of many applications of disproportionation technology are only marginal. However, the decreasing supply of petroleum feedstocks, as well as possible changes in the international chemical market, could rapidly alter this situation.

History of Crystalline Polypropylene

An early problem which one encounters in telling the history of a phenomenon or material is that of finding the true beginning. An ancient and reliable document states that “there is no new thing under the sun”[1]. Regardless of what any of us may have discovered, a harbinger or precursor can usually be cited. If one holds a hand mirror before a larger mirror, one can see an ever receding “tunnel” of reflected mirrors, and so it is as we reflect upon the origin of most discoveries.