反应详情

The same 1 L four-neck flask that was used in Example 1 was charged with 600 g of raw material containing 550 g (1.94 mol) of dimethyl 2-pentyl-3-oxo-cyclopentylmalonate produced in the same manner as in Production Example 1 and the raw material was heated to 215° C. with stirring under normal pressure. Then, the supply of water to the bottom of the reactor was started. During the supply of water, the supply rate of water was adjusted to 18 g/h from the start of the supply to the 1st hour, to 12 g/h from the 1st hour to the 2nd hour, to 6 g/h from the 2nd hour to the 3rd hour and to 3 g/h after the 3rd hour with measuring the content of water in the reaction solution by a Karl Fischer's coulometric titration (instrument: Trace-water measuring device AQ-7, manufactured by HIRANUMA SANGYO Co., Ltd.) such that the content of water was limited to 0.4% by weight or less. Then, the reaction was completed for 4 hours from the start of the supply of water. The maximum water concentration in the reaction solution was 0.14% by weight. During the reaction, the difference (X−Y) between the integrating molar number X (excluding distilled water content) of the water to be supplied and the molar number Y of the water reacted with dimethyl 2-pentyl-3-oxo-cyclopentylmalonate was 10.3% at a maximum based on the molar number of the supplied dimethyl 2-pentyl-3-oxo-cyclopentylmalonate. It was found that the reaction product contained 420 g (1.86 mol, yield: 96.0%) of methyl 2-pentyl-3-oxo-cyclopentylacetate and 5.8 g (0.027 mol) of 2-pentyl-3-oxo-cyclopentylacetic acid.

1. customproduced in the same manner as in Production Example 1
2. concentrationThe maximum water concentration in the reaction solution
3. customDuring the reaction