Preparation of mono- and diacetyl 4,4′-dimethylbiphenyl and their corresponding carboxylic acids: Reactivity, selectivity and isomer distribution studies via Lewis acid catalyzed Friedel-Crafts acetylation/oxidation
✍ Scribed by Salam J.J. Titinchi; Fadhil S. Kamounah; Hanna S. Abbo
- Publisher
- Elsevier Science
- Year
- 2007
- Tongue
- English
- Weight
- 487 KB
- Volume
- 273
- Category
- Article
- ISSN
- 1381-1169
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✦ Synopsis
Shape selective acetylation of 4,4 -dimethylbiphenyl using anhydrous aluminum chloride as catalyst is an effective route for the production of mono-and di-acetyl-4,4 -dimethylbiphenyl. Preparations, characterization and a catalytic study of the Friedel-Crafts acetylation of 4,4dimethylbiphenyl, involving use of the Perrier addition procedure are carried out in a range of solvents and under a variety of experimental conditions. The obtained ketones are isolated and identified by various physico-chemical techniques. Mono acetylation of 4,4 -dimethylbiphenyl afforded a mixture of two isomeric acetyl dimethylbiphenyls. In chloroalkane or carbon disulfide solvent, the yields of isomers were in the order: 2 -> 3-; in nitromethane 3-isomer predominated. On the other hand diacetylation of the hydrocarbon gave only the 2,3 -diacetyl isomer. The monoand di-ketones are converted to the corresponding carboxylic acids. 2-Acetyl-4,4 -dimethylbiphenyl was prepared by indirect multi-step synthetic routes. 3-D molecular modelling supports the positional assignment of the acetyl group with the results obtained from the electronic spectra.