Tetrahydrofurans continued vinyl

Corresponding replacement of halide from an unconjugated vinylic site has also been reported. The use of the sodium salts of dialkyl phosphites in tetrahydrofuran at low temperature has been found to provide the vinylic phosphonate in good yield,72 (Figure 6.22) and triisopropyl phosphite serves similarly to replace a fluoride of trifluoroiodoethene (Figure 6.23).91 The reaction proceeds ste-reospecifically to replace the fluoride cis to the iodide, and in continuing reaction the iodide is replaced. 

It is important to stir the product continually to insure effective removal of tetrahydrofuran. If appreciable solvent remains, the vinyl ether complex 1 may not crystallize readily. 

Milled rigid sheets of poly (vinyl chloride) on oven aging at 185 °C. undergo a slow initial dehydrochlorination which, if continued long enough, results in the formation of a tetrahydrofuran-insoluble fraction. This insoluble polymer dehydrochlorinates much more rapidly than the soluble polymer fractions. 

Epoxy resins and other polymers (tetrahydrofuran, vinyl ethers, styrene, etc.) can be cured when exposed to an acid or cation intermediate species. The photoactive catalyst system commonly used to cure epoxy resins and multifunctional vinyl ether materials is composed of salts of aryldiazonium, triarylsulfonium, and diaryliodonium. These systems are commonly employed in coatings and adhesives for electronic products. The acid initiator generated from the photoinitiator continues to be active even after uv curing, and so conversion of reactants and crosslinking continue even in the absence of uv light. This phenomenon is typically referred to as dark cure. 

Epoxidationof conjugated polyenes formed by thermal degradation of poly (vinyl chloride) (PVC) was carried out in cyclohexanone and tetrahydrofuran solution with w-chloroperoxybenzoic acid (mCPBA). PVC was thermally degraded in the solid state under continuous nitrogen flow at 200 °C for 30 min leading to 0.6 mol% double bonds in the polymer chain as determined from the UV-visible spectrum of... 

In this paper we describe the preparation and the properties of the title triblock with a low vinyl-1,2 (or 3,4 in the case of polyisoprene) polydiene center block. Two different solvent systems were used as the media of polymerization. In the first system, the polydiene center block was prepared in cyclohexane. Alpha-methylstyrene (AMS) and a polar solvent tetrahydrofuran (THF) were then added. This was followed by a slow and continuous styrene addition to complete the end block preparation. In the second system, AMS itself was used as the solvent with no other solvent added. The second solvent system enabled us to use several different polymerization schemes. The center block could be prepared first to form a tapered or untapered triblock. The end block copolymer also could be prepared first and then the diblock and then coupled to form a tri- or a radial block polymer. Instead of coupling, more styrene could be added to complete the triblock. All these different routes of preparation were used in this work. 

C6H5-C = CHC4Hg-n from a-diazoketones. Ethereal methyllithium added dropwise at 0 to a soln. of di-n-butyl-(l-phenyl-l-hexenyloxy)borane prepared from diazoacetophenone and tri-n-butylborane in tetrahydrofuran, the ice bath removed, stirred 1 hr. at room temp., methyl iodide added, and stirring continued 1.5 hrs. 2-hexyl phenyl ketone. Y 69%. Via vinyloxyboranes, a,a- and ,/5-dialkylated ketones can be obtained in good yield from a-diazoketones and methyl vinyl ketone respectively. F. e. s. D. J. Pasto and P. W. Wojtkowski, J. Org. Chem. 36, 1790 (1971). 

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