1, cinnamic acid reacts with alkali under heating conditions to produce a large number of foams. This reaction is the main chemical reaction to prepare cinnamic acid. Alkali reacts with acid to produce salt and water, and in this process, gas is produced, thus forming bubbles.
2. Too fast heating speed or too high reaction temperature will also produce bubbles. During the heating process, the gas in the reaction solution is released rapidly, forming bubbles. If the heating speed is too fast, the gas will escape from the solution too late to form a large number of bubbles. In addition, too high reaction temperature will also promote the release of gas, leading to the generation of bubbles.
3. Too fast stirring speed may also produce bubbles. In the process of reflux, if the stirring speed is too fast, the reaction solution will be disturbed, making it easier for gas to escape from the solution and form bubbles.
4. If some surfactants, such as sulfonated castor oil, are added in the reflux reaction, the surface tension of the liquid may be reduced, making it easier for bubbles to form and exist stably. Therefore, when preparing cinnamic acid, we should try to avoid using too many surfactants.
Matters needing attention in the preparation of cinnamic acid;
1, reaction temperature control: In the process of synthesizing cinnamic acid, it is necessary to accurately control the reaction temperature to ensure the smooth progress of the reaction and avoid side reactions. Too high a temperature will lead to the decomposition of raw materials, while too low a temperature will reduce the reaction rate.
2. Purity of reactants: The synthesis of cinnamic acid requires the use of benzaldehyde, acetic anhydride and other raw materials, and the purity of these raw materials has an important impact on the yield and quality of cinnamic acid. Therefore, before using these raw materials, we should ensure their purity and remove impurities.
3. Catalyst dosage: In the process of synthesizing cinnamic acid, the use of catalyst is necessary. The amount of catalyst should be appropriate to promote the reaction and improve the yield of cinnamic acid. However, too much catalyst may also lead to side reactions, so the dosage of catalyst should be carefully selected.
4. Product separation and purification: After the synthesis of cinnamic acid, impurities need to be separated and purified. In this process, we should avoid using too many reagents to reduce the impact on the environment and reduce the cost. At the same time, we should pay attention to avoid the decomposition of cinnamic acid caused by excessive treatment.