Mixed Diisobutylenes

Composition, weight percent Composition, weight percent  

Purity by freezing point, mol % 95.1 95.0 min Purity by freezing point, mol %  

Initial boiling point 219 Initial boiling point 216 200 min 

Specific gravity of liquid at 60/60 F 0.724 Specific gravity of liquid at 60/60 F 0.723 

Vapor presKire at KKI F. psia 1.5 apor pratsure at KKI F, psia 2.0 

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In another paper from the Jackson Laboratories of the du Pont Company (Calcott et al., 34) there is reported a repetition of some of the reactions of Simons and Archer, as well as additional ones. Mono-, di-, and 1,2,4,5 tetraisopropylbenzene were obtained from propylene and benzene both l -chloro-i-butylbenzene and di-(l/-chloro)-d-butylben-zene were obtained from 3-chloro-2-methyl-propene-l and benzene p-f-butyltoluene and di-i-butyltoluene were obtained from diisobutylene and toluene tetraisopropylnaphthalene was obtained from propylene and naphthalene naphthyl-stearic acid was obtained from oleic acid and naphthalene mixed isopropyltetrahydronaphthalene was obtained from propylene and tetrahydronaphthalene 2,4,6-triisopropylphenol was obtained from propylene and phenol a mixture of monoisopropylated m-cresols was obtained from propylene and wi-cresol and di-(s-hexyl)-diphenyl oxide was obtained from hexene-3 and diphenyl oxide. 

Butyl rubber is one product formed when isobutylene is copolymerized with a few percents of isoprene. In the Exxon process an isobutylene-methyl chloride mixture containing a small amount of isoprene is mixed at — 100°C with a solution of AICI3 in methyl chloride. An almost instantaneous reaction yields the product, which is insoluble in methyl chloride and forms a fine slurry. Molecular weight can be controlled by adding diisobutylene as a chain-transfer agent. Increased catalyst concentration and temperature also result in lowering molecular weight. The product can be vulcanized and is superior to natural rubber. A solution process carried out in C5-C7 hydrocarbons was developed in the former Soviet Union.471,472... 

Sample Solutions Dissolve 1 g of sample, accurately weighed, in 95 mL of diisobutylene, filter into a 100-mL volumetric flask, dilute to volume with solvent, and mix (Solution 1). Transfer 50.0 mL of Solution 1 into a tared dish, evaporate on a steam bath for about 1 h, and then evaporate to dryness by heating in a vacuum oven at 70° for 2 h or to constant weight. Calculate the concentration, C3, in grams per 100 mL, of Solution 1. Prepare Solutions 2 and 3, respectively, by diluting 5.0-mL and 10.0-mL portions of Solution 1 to 50.0 mL with solvent, and then calculate the concentration of each (C2 and C3, respectively). 

Isobutylene, CH2=C(CH3)2, is predominantly produced from cracked petroleum gases, and also, partially, by the dehydration of /-butanol. In industrial polymerizations, isobutylene is liquefied on addition of some diisobutylene, and mixed with about the same quantity of liquid ethylene and then cationically polymerized at -80°C with BF3/H2O. The diisobutylene acts as chain transfer agent and regulates the molar mass. The ethylene does not polymerize under these conditions on the other hand, it dissipates the heat of polymerization by volatilizing. 

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