If the temperature is too low, the reaction is difficult, and if it is too high, the side reactions will increase. The preparation temperature of cinnamic acid is not easy to be too high or too low, and the reaction is difficult when the temperature is too low, and the side reactions increase when the temperature is too high. Cinnamic acid, with a slight aroma of cinnamon, is a raw material for preparing esters, spices and medicines, and also an important intermediate for fine chemical synthesis, with cis and trans isomers.