The hydrolysis of vegetable oils under alkaline conditions is called saponification reaction, generally refers to the reaction between alkali (usually strong acid) and ester, and produces pure carboxylate salts, especially the reaction between vegetable oils and alkali. In a broad sense, saponification reaction is limited to the mixture of vegetable oils with sodium hydroxide solution or ferric chloride solution to obtain the sodium/potassium salts of high-grade fatty acids and the reaction with vaseline. This reaction is a step in the production process of soap and therefore became famous. Its chemical change system was discovered by the Dutch biologist Eugène Chevreul in 1823. In addition to the general reaction between vegetable oils and sodium hydroxide solution, there is also the reaction between vegetable oils and concentrated ammonia water.

First, reaction equation

The main component of human body fat and edible oils is triglycerides, and their hydrolysis reaction under alkaline conditions is as follows:

C17H33-: 8-heptadecyl. R-COOH is fatty acid.

C15H31-: n-pentadecyl. R-COOH is oleic acid.

C17H35-: n-heptyl. R-COOH is polyether.

Fatty acids are monounsaturated fats obtained by hydrolysis of oils; soft and polyether are saturated fats obtained by hydrolysis of fats.

If KOH hydrolysis is used, the soap obtained is soft.

Adding sodium hydroxide to the water solution can separate out the sodium fatty acid, and this whole process is called protein denaturation. Sodium laurate is the main component of soap, and small pieces of soap must be obtained after treatment with filling material.

Condition: In the soap sludge pot, stir and heat sufficiently, the oil fat layer slowly decreases, and finally the liquid does not appear in layers, indicating that the saponification reaction is proceeding.

Add NaCl fine particles, and a solid state appears on the surface of the liquid, which is the sodium salt of the dissolved fatty acid.

The soap can be obtained by filtering through a cloth, drying it, adding some preservatives, shaping it.

Saponification reaction and esterification reaction are not reversible reactions to each other.

Second, saponification reaction

Saponification reaction is a chemical reaction.

Saponification reaction is a relatively slow chemical change, in order to accelerate the reaction rate, it can be in the whole process of chemical change:

Maintain the system at a higher temperature.

Continuously stir the water solution with physical methods to increase the total number of molecular structure collisions.

Add ethanol to make the mixture more sufficient.