Isobutylbenzene

Chemical properties

Isobutyl Benzene is an organic, aromatic, neutral and colourless liquid that has a specific gravity of around 0.852. Less dense than water and insoluble in water, soluble in ethanol, ether, benzene and acetone. Vapors heavier than air.

Physical properties

Clear, colorless, liquid with an odor resembling butylbenzene, tert-butylbenzene, ethylbenzene, or toluene. An odor threshold concentration of 80 μg/kg was reported (quoted, Verschueren, 1983)

The Uses of Isobutylbenzene

Isobutylbenzene is used as an intermediate for perfumery and analgesic anti-inflammatory (Ibuprofen). It is also used as an internal standard in the study of increased pigmentation and floral scent levels in Pap1-transgenic petunia.

Preparation

Isobutylbenzene synthesis: Isobutyrophenone, underwent a Wolff–Kishner reduction using hydrazine hydrate and strong base conditions to synthesize isobutyl benzene. The solvent for this reaction was replaced with the more sustainable solvent glycerol. The glycerol for this reaction was obtained from the synthesis of biodiesel. The reaction was allowed to heat at reflux (149–155 °C) for a period of three hours. An average 51 % yield of isobutyl benzene was obtained from the solar synthesis, compared to a 55 % yield from an in-lab, electrical heating analysis.

Definition

ChEBI: Isobutylbenzene is an alkylbenzene that is benzene carrying an isobutyl substituent.

Synthesis Reference(s)

Journal of the American Chemical Society, 73, p. 4343, 1951 DOI: 10.1021/ja01153a092
Synthetic Communications, 26, p. 763, 1996 DOI: 10.1080/00397919608086751
Tetrahedron Letters, 27, p. 6369, 1986 DOI: 10.1016/S0040-4039(00)87811-9

General Description

Isobutylbenzene is synthesized by the isopropylation at the side chain over Na, K and Cs exchanged zeolites.

Hazard

Moderate fire risk. Toxic in high concentration, a skin and eye irritant.

Environmental Fate

Biological. Oxidation of isobutylbenzene by Pseudomonas desmolytica S44B1 and Pseudomonas convexa S107B1 yielded 3-isobutylcatechol and (+)-2-hydroxy-8-methyl-6-oxononanoic acid (Jigami et al., 1975).
Chemical/Physical. Complete combustion in air yields carbon dioxide and water vapor. Isobutylbenzene will not hydrolyze because it has no hydrolyzable functional group.