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温度

0 °C

A solution was made of α-campholenic aldehyde (200 g) in acetone (2 liters) and cooled to 0° C. Jones reagent was prepared from 115 ml conc. sulfuric acid, 500 ml water and 134 g of chromium (VI) oxide. The reagent (400 ml) was added to the solution at 0° C. over a period of 30 minutes. After an additional 15 minutes at 0° C. the acetone was removed by decantation and the residual chromium salts were washed with an additional 200 ml acetone. The combined acetone solution was concentrated to 1 liter, diluted with 10% aqueous sodium hydroxide (1 liter) and washed with CH2Cl2 (2×1 liter). The aqueous phase was acidified with 25% sulfuric acid and extracted with CH2Cl2 (2×1 liter). Concentration of the CH2Cl2 solution yielded an oil (145 g) which was distilled under reduced pressure to give 116 g of a yellowish liquid; bp 121° C. @ 2.2 mm Hg; analysis: 98% (CW 20M fused silica column, 180° C.) α-campholenic acid.

1. customAfter an additional 15 minutes at 0° C. the acetone was removed by decantation
2. washthe residual chromium salts were washed with an additional 200 ml acetone
3. concentrationThe combined acetone solution was concentrated to 1 liter
4. additiondiluted with 10% aqueous sodium hydroxide (1 liter)
5. washwashed with CH2Cl2 (2×1 liter)
6. extractionextracted with CH2Cl2 (2×1 liter)