反应详情

85.1 g (0.5 mol) of the acid obtained according to paragraph (c), namely 2-carboxy-2,4-dimethylcyclopent-4-en-5-olone, are treated with 851 of 10% sulphuric acid and the mixture is refluxed for 45 minutes. For the working-up, the mixture is adjusted to pH 7 with 2 N sodium hydroxide solution and then extracted three times with methylene chloride. The combined organic phases are dried over sodium sulphate and dried in a high vacuum for 1 hour. There are obtained 57.4 g (91%) of crystalline 3,5-dimethylcyclopent-2-en-2-olone of melting point 93°-94° C. The product is identical with the product obtained according to paragraph (c) of Example 4.

1. temperaturethe mixture is refluxed for 45 minutes
2. extractionextracted three times with methylene chloride
3. dry with materialThe combined organic phases are dried over sodium sulphate
4. customdried in a high vacuum for 1 hour