Nitric Acid → (1R,6S)-2,2,6-Trimethylcyclohexanecarboxylic acid

Participants

Reaction Conditions

Reaction Steps

In a 300-ml 4-necked flask equipped with a condenser, a thermometer, a dropping funnel, and a stirrer was placed 42 g of nitric acid (aqueous 60% solution), and the temperature was raised to 55° C. by heating. To the solution was added dropwise 100 g (0.65 mole) of (1R,6S)-2,2,6-trimethylcyclohexanecarbaldehyde (10) [composition: 90% of the (1R,6S)-form, 10% of the (1S,6S)-form] synthesized in Synthetic Example 4-A) with stirring over a period of 2 hours. After carrying out the reaction for 3 hours at the same temperature, the reaction mixture was washed with water with 100 g of toluene and 100 g of water at room temperature, followed by separating an organic layer from an aqueous layer. The organic layer was washed thrice with 100 g of a saturated aqueous sodium chloride solution, followed by separating the organic layer from an aqueous layer. The toluene was distilled off from the organic layer by an evaporator under reduced pressure to provide 109 g of crude (1R,6S)-2,2,6-trimethylcyclohexanecarboxylic acid (11) [composition: 91% of the (1R,6S)-form, 9% of the (1S,6S)-form; melting point: 44° C. to 54° C⟧

Provenance & Evidence