There are three ways to synthesize Benzyl Salicylate. One is to catalyze the esterification reaction between salicylic acid and benzyl alcohol, and the other is to carry out the esterification exchange reaction between methyl salicylate and benzyl alcohol. The third is the phase transfer catalytic reaction between salicylic acid and benzyl chloride. Although the cost of the three methods is lower, the impurities produced have a greater impact on its aroma.
Under the condition of using polyethylene glycol-400 as a phase transfer catalyst, the product yield is high, but the process is complicated and the operation is inconvenient. Among tetrabutylammonium bromide, triethylbenzylammonium chloride and polyethylene glycol-400 phase transfer catalysts, tetrabutylammonium bromide has the best catalytic effect, and its reaction time is short and easy to operate. industrialization.
Method 1: Add sodium salicylate (0.25mol, 40.2g) and benzyl chloride (0.1mol, 12.6g) to a three-necked round-bottomed flask equipped with a thermometer and a reflux condenser, and add 200mL of N , N-dimethylformamide solvent. The reaction mixture was magnetically stirred and heated to 100°C for reaction. As the reaction progressed, white sodium chloride precipitated out. After the reaction, the precipitate was removed by filtration. The filtrate was first collected by vacuum distillation to collect N,N-dimethylformamide (50°C-51°C/2660Pa) for recycling, and then collected by vacuum distillation to collect Benzyl Salicylate (170°C-172°C/533Pa) 22.43g, yield 98 . 4%.
Method 2: Add a certain amount of benzene, salicylic acid, benzyl alcohol, DCC and DMAP to a dry 250 mL round-bottomed flask, immediately a white flocculent precipitate is formed, and stand at room temperature for 3.5 h. Suction filtration, the filtrate was washed several times with 10% Na2CO3 solution, then washed with saturated NaCl solution until neutral, added a certain amount of anhydrous MgSO4, filtered overnight, recovered benzene by distillation, then rectified under reduced pressure, collected 205 ℃ ~ 208 ℃ / 3465 Pa product is Benzyl Salicylate.
Method 3: A new method for the synthesis of Benzyl Salicylate by solid-liquid phase transfer catalysis: take salicylate, benzyl chloride, catalyst A and catalyst B into the reaction vessel, and react at 80-200°C for 2-20 hours. After the reaction is completed , add water to separate the layers of the reaction solution, separate the organic layer, then wash, dehydrate and distill the organic layer in turn to collect the fraction at 164-165°C/725-735Pa (that is, a pressure value in 725-735Pa The boiling point is 164-165 ℃ fractions) to obtain the product; the catalyst A is a combination of one or more of crown ethers, crown ether derivatives and PEG200-6000; the catalyst B is an alkali metal Halogen salt; the molar ratio of the salicylate to benzyl chloride is 0.8-2:1; the molar ratio of the catalyst A to benzyl chloride is 1-10:100, and the molar ratio of the catalyst B to benzyl chloride The molar ratio is 1-10:1000.
