Propene oxide tetrahydrofuran

The Keggin-type heteropolyacid (hereafter abbreviated HPA) is a unique catalyst material because it has the dual catalytic functions of strong acidity and high oxidizing capacity [1-5]. HPA has been applied commercially as an efficient catalyst in several petrochemical processes, including the direct hydration of propene (1972) [6,7], isobutene (1984) [8] and n-butenes (1989) [9], the oxidation of metha-crolein to methacrylic acid (1982) [10], the oligomerization of tetrahydrofuran to polymeric diols (1985) [11], and the oxidation of ethene to acetic acid (1997) [12]. 

Danheiser used retro-1,2-Brook rearrangement of allyl silyl ethers in a convenient route to a,/ -unsaturated acyl silanes. For example, 2-methyl-2-propen-l-ol was converted to the trimethylsilyl ether and, in a single-pot process, deprotonated by addition of 1.2 equiv terr-butyllithium. Protonation with a solution of acetic acid in tetrahydrofuran gave the of-hydroxyallylsilane 144. Removal of volatiles from the thermally sensitive product provided 95-percent-pure material that was oxidized to the a,P-unsaturated acyl silane 145 under Swem conditions. ... 

Grassie and co-workers a.l23, a.l24] found that under inert conditions at temperatures above about 210 °C the polyurethane linkage disappears without any volatile products being formed, and the initial degradation step is seemingly a simple depolymerisation reaction. The two monomers are the primary products, and all the other products, which include carbon dioxide, butadiene, tetrahydrofuran, dihydrofuran and water as volatile products and carbodiimide and urea amide in the condensed phase, are formed from the monomers in a complex set of secondary reactions while they are diffusing from the hot polymer. This is unlike under oxidative conditions, whereby the first step involves the scission of the polyurethane molecule into primary amine, carbon dioxide and propenyl ether species, the latter leading to propene formation. The mechanism is reduced to a... 

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