Adipaatesters

Esters exist widely in nature. Lower esters have an aromatic odor and are present in the flowers and fruits of plants. Fat is the glyceryl ester of higher fatty acids, which is an indispensable substance for life. Wax obtained from animals or plants is also composed mainly of lipids. Tannin is the glucose-ester of gallic acid, the antibiotic erythromycin is the lactone, and the insecticide pyrethrin is the ester of chrysanthemum acid.

According to the chemical structure. Can be divided into: (1) Phthalate esters; (2) Aliphatic dibasic acid esters; (3) Phosphate esters (4) Epoxy compounds; (5) Polymeric plasticizers; ( 6) Benzene polyester; (7) Chlorine-containing plasticizer; (8) Alkyl sulfonate ester; (9) Polyol ester; (10) Other plasticizers.

Adipic acid and corresponding alcohol are formed through esterification reaction and distillation purification under the action of catalyst.

Use a catalyst that has good catalytic activity and can be removed from the system without neutralization and water washing, or a catalyst that forms a homogeneous phase with the ester at the reaction temperature and precipitates in a solid state after lowering the temperature.

The carboxylic acid and alcohol can be heated in the presence of a small number of catalysts (concentrated sulfuric acid, dry hydrogen chloride, strong acid type ion exchange resin) to form esters. This reaction is called esterification. Esterification is a reversible reaction, and when equilibrium is reached, a certain number of reactants and products are present.

The functional group of adipate esters is -COO-, which is formed by dehydration of carboxyl group (-COOH) and hydroxyl group (-OH).

Dioctyl adipate is a typical excellent cold-resistant plasticizer for polyvinyl chloride. It has high plasticizing efficiency and little discoloration when heated. It can give products excellent low-temperature flexibility and light resistance, and has a certain degree of water resistance.

Since adipic acid is a binary carboxylic acid, if the alcohol involved in the reaction is a monol, then one molecule of adipic acid reacts with two molecules of a monol to produce a molecule of adipate esters. After the coefficients corresponding to the chemical reaction are multiplied by their respective molecular weights, the ratio between the three products is the ratio of raw material consumption.

The most cost-effective plasticizers are dibutyl phthalate and dioctyl phthalate.

Dimethyl phthalate

The word “ester” can be preceded by the corresponding carboxylic acid and alcohol names. The word “alcohol” can generally be omitted, that is, “some” acid “some” ester. But the ester of polyols, generally put the “acid behind, called” an alcohol an acid ester.”

Heating and adding catalyst can only accelerate the reaction speed, and has no effect on the composition of the balanced material. In order to increase the yield of esters, excessive carboxylic acids and alcohols are often added, or the resulting water is constantly removed from the reaction mixture. If the boiling point of the ester produced is very low, the ester can also be steamed out. In short, the equilibrium is destroyed to improve the yield of ester. For example, the industrial production of ethyl acetate is to use excessive acetic acid, the generated ethyl acetate and water azeotrope (water 8.6%, ethyl acetate 91.4%, constant boiling point 70.45℃) to steam out, so that the balance is destroyed, and then continue to add acetic acid and ethanol, continue to steam ethyl acetate and water, continuous production.

The hydrolysis of esters in alkali solution is also called saponification reaction, which is because the advanced fatty acid salt obtained by alkaline hydrolysis of grease is the reason of soap.