The Cationic Telomerization of Butadiene with Its Hydrochloride

Abstract

The telomerization of butadiene with its hydrochlorides (1-chlorobutene-2 and 3-chlorobutene-1) in the presence of metal halides was investigated. The aim of the present investigation is to explore methods of controlling the molecular weight of the telomer under various reaction conditions, and to determine the properties and structures of the telomers obtained. Ferric chloride, aluminum chloride and titanium tetrachloride were the most active among the catalysts investigated. It was found that the main factors determining the average molecular weight and the ratio of simple adduct of butadiene with chloride to higher telomers are the selection of catalyst, solvent, chloride/butadiene ratio and the degree of conversion of the reaction. The molecular weight of the telomer increases with increase in the conversion of the reaction and with decrease in the chloride/butadiene ratio.When ethyl ether or nitro-compounds was used as a solvent, the telomers obtained were of lower molecular weights and higher degree of unsaturation than those obtained in halogenated hydrocarbons. The two isomeric hydrochlorides of butadiene gave telomers of almost the same structure. The simple adduct of butadiene with the chloride isolated by distillstion turned out to be a mixture of three isomers; 1-chlorooctadiene-2, 6, 3-chlorooctadiene-1, 6 and 1-chloro-5-methylheptadiene-2, 6.The higher telomers appear not to be of the normal structure; H(C4H6)nCl. The low degree of unsaturation and the high chlorine content suggest the occurrence of some undesirable side reactions. It was found that the types of linkage of butadiene unit in the telomers are not much affected by the reaction conditions.The telomers were reacted with potassium hydroxide in benzyl alcohol. The telomers of the lower molecular weight entered into reaction more easily than higher telomers.