反应详情

A 1 L four-neck flask equipped with a stirrer, a supply unit, a thermometer and a rectifier was charged with 600 g of raw material containing 545 g (1.92 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 180° 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 6 g/h from the start of the supply to the 2nd hour, to 3 g/h from the 2nd hour to the 8th hour and to 1.2 g/h after the 8th 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 16 hours from the start of the supply of water. The maximum water concentration in the reaction solution was 0.21% 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 14.8% at a maximum based on the molar number of the charged dimethyl 2-pentyl-3-oxo-cyclopentylmalonate. It was found that the reaction product contained 423 g (1.87 mol, yield: 97.3%) of methyl 2-pentyl-3-oxo-cyclopentylacetate and 10.8 g (0.051 mol) of 2-pentyl-3-oxo-cyclopentylacetic acid.

1. customA 1 L four-neck flask equipped with a stirrer
2. customproduced in the same manner as in Production Example 1
3. concentrationThe maximum water concentration in the reaction solution
4. customDuring the reaction