181. The activation of carbon–carbon triple bonds by cationic catalysts. Part II. The interaction of stannic chloride with phenylacetylene and with pent-1-yne in benzene

Abstract

Phenylacetylene and pent-l-yne react with stannic chloride in benzene to give a complex containing two molecules of the acetylene and one of stannic chloride. The presence of hydrogen chloride does not affect this reaction but brings about the production of cz trace of polymer containing conjugated double bonds.WE have previously investigated the action of trichloroacetic acid on phenylacetylene ; in this Paper we study the action of stannic chloride on phenylacetylene and on pent-l-yne with and without hydrogen chloride present. EXPERIMENTAL AND RESULTSMaterials.-Phenylacetylene was purified by the method described earlier. It was dried under vacuum by prolonged storage over barium oxide followed by distillation. When rigorously dried material was required, it was purified as follows. Tri-isobutylaluminium was added in successive small quantities using the high vacuum technique employed earlier for the addition of titanium tetrachloride to olefins.2 The system became yellow and addition of alkyl was continued until evolution of gas ceased; it was then outgassed and repeated distillation under vacuum gave the acetylene freed from all traces of tri-isobutylaluminium. The infrared spectrum of the acetylene after this treatment was identical with that before treatment. When phenylacetylene, dried in this way, was mixed with stannic chloride, a pale yellow solution resulted, whereas the addition of stannic chloride to the undried acetylene produced a black solution and a solid precipitate. The addition of both stannic chloride and tri-isobutylaluminium to the purified acetylene resulted in an immediate red-brown precipitate and the solution rapidly became viscous.These experiments show that the phenylacetylene after treatment with tri-isobutylaluminium (a) has not been attacked by the alkyl, (b) is drier than before treatment, and ( G ) contains no alkylaluminium, or does so in negligible concentration.Pent-l-yne was rigorously dried by this same technique using triethylaluminium as the desiccant.were purified as described earlier.Triethylaluminium and tri-isobutylaluminium (given by Petrochemicals Ltd., Carrington) were transferred under dry nitrogen into a high vacuum system where they were degassed and passed into a series of bulbs which were then sealed.Procedure.-A solution of the acetylene in benzene was made up and introduced into dilatometers under high vacuum conditions.3 Known amounts of stannic chloride and hydrogen chloride were added and the reaction was followed dilatometrically as described earlier. Reaction products were obtained either from reaction solutions which had proceeded to completion or, when large quantities were required for analysis, large dilatometers were used. Solvent and residual acetylene were distilled off leaving the reaction product-a blackish solid from the reaction of phenylacetylene and a brown liquid from the reaction of pent-l-yne. Distillation under vacuum of the liquid product from pent-l-yne gave a colourless oil, b. p. 60°/0.05 mm., and a black residue remained (-5%).The ...

Polymerization of Phenylacetylenes. I. Polymerization of Phenylacetylene Catalyzed by WCI6 and MoCI5

“…This paper is concerned with the formation of poly(phenylacetylene) having high molecular weight (5,(0)(1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)000). Phenylacetylene was found to form the polymer in a high yield by using WClg and M0CI5 as catalysts.…”