Bis(acetylacetonato) dioxomolybdenum(VI) catalysed rearrangement of methylbutynol in the presence of ultrasound.
The molybdenum (VI) catalysed rearrangement of methylbutynol was carried out under the influence of ultrasound (20 kHz). Surprisingly, 2-methylpropene (isobutene) was found as the main product. The formation of isobutene can be explained by rearrangement to prenal, oxidation to 3,3-dimethylacrylic acid and then decarboxylation. 3,3-Dimethylacrylic acid was decarboxylated in the presence of ultrasound and a catalyst; without a catalyst or without ultrasound (at 50 degrees C) it remained unchanged.
F. Hoffmann-La Roche Ltd, Vitamins and Fine Chemicals Division, Basel, Switzerland. werner.bonrath@roche.com
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