Using n-heptanol to carry out radical addition reaction with acrylic acid or methyl acrylate in the presence of a free radical initiator to prepare propyl-decalactone, which is the synthesis route of propyl-decalactone that can form large-scale production at present. Using n-heptanol and acrylic acid as starting materials, using di-tert-butyl peroxide as an initiator, adding a reaction solvent, firstly adopting a “one-pot cooking” method, free radical addition to synthesize the crude product of gamma-decalactone, and distillation to recover the reaction Solvent, then prepare gamma-decalactone by rectifying and purifying, in this synthesis process, the by-product cannot be separated from the reaction system in time, cause the reaction yield to drop, the reaction time is prolonged, and the product contains low-boiling impurities. Grease odor, high boiling impurities and poor oil consumption of isomers affect the final product aroma quality of Gamma-Decalactone.
CN201810882253.4 overcomes the common problems of complex separation and purification process, high energy consumption, low reaction yield, and unpurified product aroma quality in existing synthetic methods for gamma-decalactone, and provides a simple process and high reaction yield , the reaction speed is fast, the overall cost is relatively low, it is beneficial to form industrialized scale production, and is easy to realize the synthetic method of the gamma-decalactone synthetic fragrance of product serialization.
A method for synthesizing Gamma-Decalactone synthetic fragrance by reactive distillation, it is characterized in that: may further comprise the steps:
(a) 120g of heptanol, 90g of Gamma-Decalactone, 1g of catalyst sodium borohydride and 15g of initiator di-tert-butyl peroxide are added to the 500mL there-necked flask according to the proportion of ingredients, and the electromagnetic stirrer and the heat and cold exchange integrated machine are turned on, Keep the temperature at 20±5°C to obtain the batching mixture;
(b) take by weighing 360g heptanol again, join in the 1500mL heater of reactive distillation column, open electromagnetic stirrer and cold and heat exchange integrated machine, the temperature of heater is raised to 115～175 ℃ and insulation, then by The batching mixture in the step (a) is fed into the reaction zone of the reactive distillation column by a dripping pump; the temperature of the heater is controlled to be 145-175° C. during the dripping, and the dripping time is controlled to be 2-4h;
(c) open the tower top condensed water of reactive rectifying tower, separate out by-product tert-butanol and methyl alcohol from the tower top of reactive rectifying tower, separate out excess unreacted heptyl alcohol from the rectifying section side line of reactive rectifying tower Alcohol, the Gamma-Decalactone crude product is separated from the column bottom;
(d) transfer the Gamma-Decalactone crude product of step (c) into the rotary evaporator, open the cold and heat exchange integrated machine connected with the rotary evaporator, open the low vacuum, the control temperature is 95～125 ℃, and the rotational speed is 50～ 160r/min, pressure is 6667～10000Pa, collect low boiling point impurities and residual heptanol;
Then, the temperature is controlled to be 115-155° C., the rotational speed is 50-160 r/min, and the pressure condition is 3333-6667 Pa, and the gamma-decalactone is collected by collection.