The traditional synthetic method of gamma-decalactone generally adopts the following methods:
1. Obtained by co-heating ω-decenoic acid and sulfuric acid. During the reaction, the double bond position is transferred from the chain to the β, γ position, and then lactonized. Cothermal reaction with ω-decenoic acid and sulfuric acid will generate more by-products in the reaction process, so the reaction yield is low, the by-products are more, and the reaction selectivity is relatively low and the efficiency is low , and this route uses sulfuric acid as a catalyst, once large-scale production is formed, a large amount of three wastes will be generated in subsequent treatment;
2. Use cerium, vanadium and other high-priced acetate or manganese acetate as an oxidant, and it is obtained by reacting α-heptene with acetic acid. Using metal or the corresponding acetate as the oxidizing agent will produce a large amount of wastewater containing heavy metals after the reaction. From the perspective of green chemistry and environmental protection, this route requires high cost and is not conducive to large-scale process production.
3. Reformatsky reaction synthesis method
Condensation of a carbonyl compound (octylal) with a β-halogenated ester (β-bromopropionate) in the presence of zinc to obtain a β-hydroxy acid ester, which is then dehydrated under acid catalysis to generate the corresponding γ-decane ester. Organozinc reagents are used in the synthesis process, and must be reacted in an inert solvent, and further research is needed to realize industrialization.
4. Preparation by biocatalysis
GDL enzyme has catalytic activity in non-aqueous phase, and it is widely used in organic synthesis. Among them, lipase is the most widely used, which is cheap, does not require coenzymes, and has strong substrate adaptability. Lipase can not only catalyze the hydrolysis reaction of fat, but also catalyze the esterification reaction and transesterification reaction in the organic phase, including catalyzing the formation of lactones from hydroxyl fatty acids. However, it is very difficult to cyclize these hydroxy acids by conventional methods, and the yield is very low. It is much easier to complete the cyclization process in an organic medium by an enzymatic method, which undoubtedly provides a great opportunity for the large-scale marketization of this type of aroma lactone. good way. Sometimes, when conditions permit, some other biotechnology enzyme catalysis methods can also be used. Perhaps in the near future it will also become one of the important means to solve the problem of marketization of lactone bioactive substances.
5. Free radical addition
Use n-heptanol and acrylic acid or methyl acrylate to carry out free radical addition reaction in the presence of a free radical initiator to prepare gamma-decalactone, which is currently a synthetic route for gamma-decalactone that can be produced on a large scale. Using n-heptanol and acrylic acid as starting materials, di-tert-butyl peroxide as an initiator, adding a reaction solvent, first adopting a “one-pot cooking” method, free radical addition synthesis of crude gamma-decalactone, distillation and recovery reaction Solvent, and then prepare gamma-decalactone by rectification and purification. During the synthesis process, the by-products cannot be separated from the reaction system in time, resulting in a decrease in reaction yield, prolonged reaction time, and low-boiling impurities in the product. Grease odor, high boiling point impurities and bad smell of isomers affect the aroma quality of the final product of gamma-decalactone.
CN201810882253.4 overcomes the problems of complex separation and purification process, high energy consumption, low reaction yield and insufficient pure product aroma quality in the existing synthesis method of gamma-decalactone, and provides a method with simple process and high reaction yield , the reaction speed is fast, the overall cost is low, it is beneficial to form an industrial scale production, and it is easy to realize the synthesis method of the gamma-decalactone synthetic fragrance of product serialization.
A method for synthesizing perfume by reactive distillation, characterized in that: comprising the following steps:
(a) Add 120g of heptanol, 90g of methyl acrylate, 1g of catalyst sodium borohydride and 15g of initiator di-tert-butyl peroxide into a 500mL three-necked flask according to the proportion of ingredients, and turn on the electromagnetic stirrer and the integrated cooling and heat exchange machine , keeping the temperature at 20±5°C to obtain the ingredient mixture;
(b) Weigh 360g of heptanol again, add it to the 1500mL heater of the reactive distillation tower, turn on the electromagnetic stirrer and the integrated cooling and heat exchange machine, raise the temperature of the heater to 115-175°C and keep it warm, then put the The batching mixture in the step (a) is sent into the reaction zone of the reactive distillation tower through the dropping pump; the temperature of the heater is controlled at 145-175° C. during the dropping, and the dropping time is controlled at 2-4 hours;
(c) Open the top condensed water of the reactive distillation tower, separate the by-product tert-butanol and methyl alcohol from the top of the reactive distillation tower, and separate the excess heptan that does not participate in the reaction from the side line of the rectification section of the reactive distillation tower Alcohol, isolate the crude product of gamma decanolactone from the bottom of the tower;
(d) Transfer the gamma-decalactone crude product of step (c) into a rotary evaporator, turn on the integrated cold and heat exchange machine connected with the rotary evaporator, turn on the low vacuum, control the temperature to 95-125°C, and the rotation speed is 50~160r/min, pressure 6667~10000Pa, collect low boiling point impurities and residual heptanol;
Then control the temperature at 115-155° C., the rotation speed at 50-160 r/min, and the pressure at 3333-6667 Pa to collect the gamma-decalactone.