Polymer and Materials Science
Wiley InterScience Backfile Collection 1832-2000
Chemistry and Pharmacology
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Isobutylene tetramers (IB4) were obtained in high yield by the cationic dimerization of commercial diisobutylene (DIB) (2,4,4-trimethyl-1-pentene with isomeric impurities) with CF3SO3O3H or CH3COClO4 as catalyst. The best IB4 yields (80-90%) were achieved at 0-30°C in nonpolar solvents (n-hexane and CCl4). The major components in the IB4 produced under these conditions were 2,2,6,6,8,8-hexamethyl-4-methylenenonane (8) and 2,2,4,6,6,8,8-heptamethyl-4-nonene (9) that arose via simple linear dimerization of DIB. The yield of IB4 was almost independent of the monomer concentration ranging from 10 to 50 vol % at 0°C, but decreased at higher temperatures (〉50°C) or in a polar solvent [(CH2Cl)2] because of the formation of higher oligomers and side reactions such as cracking. A Lewis acid catalyst (AlEtCl2) resulted in a very complex mixture of C12-C20 hydrocarbons at 0°C in CCl4; the yield of IB4 was less than 40%. The catalytic difference between oxo acids and metal halides is discussed.
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