Isobutyraldehyde → 2-Cyclohexen-1-one, 4,4,6-trimethyl-

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To a mixture of isobutyraldehyde (382 g, 5.3 mole) in 400 ml of 0.8 M aqueous sodium hydroxide was added methyl isopropenyl ketone (420 g, 5.0 mole) over a 1 hr period at 25°. The mixture was then heated to 75° for 1 hr. The mixture was cooled, and the layers were separated. The organic phase was washed neutral with water. Distillation of this organic material afforded 297 g (2.15 mole, 43% yield) of the desired 4,4,6-trimethyl-2-cyclohexenone, bp 68°-69° at 10mm, nD20 1.4685, with an infrared and nmr spectra identical with that reported in the literature (JOC 33, 4060 (1968)). Continued distillation afforded a new material (116 g) with a boiling point of 100° to 120° at 0.5mm. This material slowly crystallized and was filtered and washed with hexane. These crystals proved to be 5-hydroxy-2,4,4-trimethylcyclohexanone and exhibited the following spectral characteristics: mp 105°-106°; ir (KBr) 3360 (OH), 1685 (C=O), 1250, 1195, 1135, 1111, 1029, 983 cm-1 ; nmr (CDCl3) 0.98 (d, J=6.5Hz, 3H), 1.04 (s, 3H), 1.22 (s, 3H), 1.53 (d,d,d, J=13, 8, 1.5 Hz, 1H), 1.90 (d, J=13 Hz, 1H), 2.35 (d,d, J=15, 3 Hz, 1H), 2.62 (d,d, J=15, 3 Hz, 1H), 3.85 (m, 1H); mass spectrum (m/e, (relative intensity) 156 (8), 138 (2), 100 (100), 72 (35), 70 (33) 68 (37), 56 (80), 43 (38), 41 (37).

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