Synthesis of methyl cinnamate in methyl cinnamate

Methyl cinnamate, also known as methyl β-phenylacrylate, has cocoa flavor and is mainly used in daily chemical and food industry. It is a commonly used fixative or edible essence, and also an important raw material for organic synthesis. At present, its synthesis methods include inorganic acid (such as hydrochloric acid and sulfuric acid) catalytic esterification, organic acid catalytic esterification, heterogeneous catalytic esterification and high-pressure microwave synthesis. Inorganic acid catalytic esterification method has many disadvantages, such as many side reactions, long reaction time, low product yield, serious equipment corrosion, waste water produced by post-treatment and so on. Heterogeneous catalytic esterification takes a long time and the product yield is not high (72% ~ 87%). Organic acid catalytic esterification method has short reaction time, high product yield, but high cost; Although the high-pressure microwave synthesis method can overcome the shortcomings of the first three methods, it is difficult to realize industrial production. In the 1920s, the chemistry laboratory of Princeton University found that ultrasound could accelerate chemical reactions. In the mid-1980s, the application of ultrasound in chemistry developed rapidly. Ultrasound has been applied to oxidation, reduction, addition, polycondensation and hydrolysis in organic chemistry, involving almost all fields of organic chemistry. Ultrasonic chemical method is considered as green chemistry. As a new form of energy, ultrasound is applied to organic chemical reactions, which not only enables many reactions that were impossible or difficult to carry out in the past to proceed smoothly, but also is a convenient, rapid, effective and safe synthesis technology, far superior to the traditional methods of stirring and external heating. In this paper, the synthesis of methyl cinnamate was studied by ultrasonic radiation technology. The experimental results show that the yield of methyl cinnamate synthesized by ultrasonic method is high, the reaction conditions are simple, and it is easy for industrial production. Cinnamic acid and methanol are chemically pure; Na HSO4？ H2 O is analytically pure; XRC- 1 micro melting point tester (Chengdu, China, Yike, Sichuan University

Factory); P E-2400C HN elemental analyzer (PE Company, USA); Magna-IR 550 Fourier infrared spectrometer (P E Company, USA); father

-1 sealed pressurized PTFE microwave digester (70 ml, pressure 1. 2M Pa, produced by Sichuan Institute of Analysis and Testing); KQ-200 KDB high-power numerical control ultrasonic cleaning machine (China Kunshan Ultrasonic Instrument Co., Ltd., working frequency 40 KHz). According to the research, ultrasonic catalysis promotes organic chemical reactions because liquid reactants produce countless tiny cavities under the action of ultrasonic waves, resulting in instantaneous high temperature and high pressure, thus accelerating the reaction speed. The pressure difference between the inside and outside of the cavity is very large, which makes the cavity collapse and rupture rapidly, producing a huge impact force, thus playing the role of intense stirring, making the reactants fully contact, thus improving the reaction efficiency.

Research shows that using ultrasonic radiation technology, sodium sulfate? Using H2 O as catalyst, the optimum reaction conditions for the synthesis of methyl cinnamate were as follows: the molar ratio of alkyd was 8 ∶ 1, and the amount of catalyst was 10. The ultrasonic power is 120 W and the radiation time is 2. 5h, the average yield of the product is 96. 3%. This method is simple, with high yield and industrial application value.