Dehydrogenation-acetylation of branched hydrocarbons with acetyl chloride and aluminum chloride

✍ Scribed by I. Tabushi; K. Fujita; R. Oda

• Book ID: 104222991
• Publisher: Elsevier Science
• Year: 1968
• Tongue: French
• Weight: 248 KB
• Volume: 9
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(00)89802-0

✦ Synopsis

We reported the novel rearranged dehydrogenatlon-acetylatlon of cyolohexane with acetyl chloride and aluminum chloride where 2-methyl-&-cyolopentenyl methyl ketone was obtained as the practically soie component in the I:1 reaction product. There was obtained a small amount of the 1:2 reaotlon produot (1). Now we wish to report the unrearranged dehydrogenatlon-aoetylatlon of branohed hydrocarbons with acetyl chloride and aluminum chloride. 12.9 g of acetyl chloride (0.3 mole) in 200 ml of chloroform was added into the suspension of # g (0.3 mole) of finely powdered aluminum ohlorlde in 100 ml of chloroform. The mixture became homogeneous with stirring and Into the resultant solution was added dropwelse 25 g of methylcyclopentane in 20 ml of chloroform. After 5 hours stirring, the mixture was poured onto Ice-HCl and was extracted with 150 ml of methylene chloride three times. Usual work-up of the organic layer gave 11.3 g of the distillate boiling In the range of 80-89OC at 25 mmHg, which consisted of one major component (89.516 of the above distillate and amounted to 27.4% yield based on methylcyelopentane used) and several minor components by VPC analysis with Silicon DC 550, Apiexon-greese-L and PRG 20.000. The major produot, I, was assigned as 1-methyl-ti-cyclopentenyl methyl ketone on the bases of spectral and chemical behaviors. IR spectrum of I showed the presence of cc,@-unsaturated carbonyl function (by characteristic absorption at 1685 and 1620 cm-'). This assignment was supported by the observation that I was quantitatively hydrogenated by absorbing one equivalent of hydrogen on the.Pd-C catalyst, giving a saturated ketone (IR, 1705 cm-'). Nmr spectrum of I gave further support for the structural assignment : 7.89~ singlet (3H), 7.97 and 8.00~ singlets (3H) and