GB1227425A - - Google Patents

Abstract

1,227,425. Lithium adducts. LITHIUM CORP. OF AMERICA. 3 April, 1968, No. 15956/68. Heading C2J. Lithium/conjugated polyene adducts are made by gradually adding the conjugated polyene (which term includes vinylidene substituted aromatic compounds) to a mixture comprising finely divided lithium dispersed in an inert liquid paraffin, an inert liquid ether and optionally a volatile aromatic hydrocarbon, maintaining the reaction mixture at below 25‹ C., adding a hydrocarbon to the reaction mixture which comprises a volatile aromatic hydrocarbon if not previously included in the mixture and removing unreacted lithium to form a solution of the adduct, said ether having been removed either prior to the addition of the hydrocarbon and after the addition of the polyene or after the addition of the hydrocarbon. The solution thus obtained contains 0À6-1À5 mol/l. of the adduct, 65-100% wt. of said adduct being constituted of a mixture of dimers and trimers of said polyene, the dimers constituting at least 1À5 times the trimers. The polyene is preferably added at a rate of 0À25-10 ml/min./gm. atom of lithium to a mixture containing 1À5-4 g. atoms/1. of lithium. The polyene may be isoprene, 1,3-butadiene, dialkyl butadienes, allocimene, myrcene, styrene, α- methyl styrene, 3-vinyltoluene, and 1-vinyl naphthalene. The inert paraffin may be a mineral oil, kerosene, iso-octane, n-heptane or n-octane. The ether may be glycol dimethyl ether or diethylene glycol dimethyl ether. Excess ether may be removed by purging with inert gas, by vacuum and/or warming. Suitable volatile aromatic hydrocarbons include benzene, toluene and xylene. A catalyst, in the form of a preformed lithium/conjugated polyene adduct, may be added to the reaction mixture. The adduct may be hydrogenated to form saturated hydrocarbons or they may be used as stereospecific catalysts for the polymerization of conjugated dienes, e.g. isoprene and 1,3-butadiene.