A method for improving the optical purity of l-isopulegol by chiral resolution
A technology for isopulegol and chiral separation, applied in organic chemistry methods, chemical instruments and methods, organic chemistry, etc., capable of solving problems such as low yield, harsh conditions, low optical purity of L-isopulegol, etc. problems, achieve low price, mild reaction conditions, reduce production energy consumption and equipment costs
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Embodiment 1
[0039] Add 15.4g (0.1mol) D, L-isopulegol, 7.7g (0.05mol) L-linalool, 0.003g sodium dodecylsulfonate and 75g ethanol to a 200mL jacketed crystallization kettle, heat to 70°C and the reaction was stirred at this temperature for 3 hours. After the reaction was completed, it was slowly cooled to 10° C., and the intermediate L-isopulegol·L-linalool was obtained through centrifugation.
[0040] Dissolve the above-mentioned intermediate L-isopulegol·L-linalool in 100 mL of water, add 0.1 mol / L aqueous sodium hydroxide solution to adjust the pH value to 6.5, stir for 3 hours, the intermediate decomposes, and then passes through the gel Chromatography (using gel permeation chromatographic columns in series, mobile phase is tetrahydrofuran, flow rate 0.5mL / min, time 45min, chromatographic column temperature 35 ℃) to obtain high-purity L-isopulegol. Detected by gas chromatography, the optical purity of the product was 99.0% e.e., and the total yield was 90.3%.
Embodiment 2
[0042]Add 15.4g (0.1mol) D, L-isopulegol, 18.5g (0.12mol) L-linalool, 0.015g sodium dodecylsulfonate and 300g isopropyl acetate to 500mL jacketed crystallization In the still, it was heated to 80°C, and the reaction was stirred at this temperature for 4 hours. After the reaction was completed, it was slowly cooled to 25° C., and the intermediate L-isopulegol·L-linalool was obtained through centrifugation.
[0043] Dissolve the above intermediate L-isopulegol L-linalool in 100mL water, add 0.1mol / L sodium carbonate aqueous solution to adjust the pH value to 7.5, stir for 4 hours, the intermediate decomposes, and then pass through gel chromatography Method (using gel permeation chromatographic columns in series, mobile phase is tetrahydrofuran, flow rate 2.0mL / min, time 45min, chromatographic column temperature 40 ℃) to obtain high-purity L-isopulegol. Detected by gas chromatography, the optical purity of the product was 99.4% e.e., and the total yield was 81.2%.
Embodiment 3
[0045] Add 15.4g (0.1mol) D, L-isopulegol, 12.3g (0.08mol) L-linalool, 0.008g sodium dodecylsulfonate and 150g ethyl acetate to a 500mL jacketed crystallization kettle , heated to 75°C, and stirred at this temperature for 3 hours. After the reaction was completed, it was slowly cooled to 15° C., and the intermediate L-isopulegol·L-linalool was obtained through centrifugation.
[0046] Dissolve the above-mentioned intermediate L-isopulegol·L-linalool in 100 mL of water, add 0.1 mol / L sodium bicarbonate aqueous solution to adjust the pH value to 6.8, stir for 3 hours, the intermediate decomposes, and then passes through the gel Chromatography (using gel permeation chromatographic columns in series, mobile phase is tetrahydrofuran, flow rate 1.0mL / min, time 45min, chromatographic column temperature 40 ℃) to obtain high-purity L-isopulegol. Detected by gas chromatography, the optical purity of the product was 99.8% e.e., and the total yield was 86.4%.
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