Dicarboxylate

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.

It is formed by the reaction of organic acids containing two carboxyl groups with various alcohols.

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 Dicarboxylate is -COO-, which is formed by dehydration of carboxyl group (-COOH) and hydroxyl group (-OH). Dicarboxylate have the characteristics of typical ester functional groups, including saponification and hydrolysis reactions. Transesterification reactions are mainly used to convert ester products into useful plasticizers.

Dicarboxylate as solvent, plasticizer, organic synthesis intermediate, widely used in paint, paint, ink, plastics, synthetic rubber, medicine and other fields. For example, dimethyl glutarate is widely used in the pharmaceutical field and other plastics, paints, coatings and other chemical industries. Dimethyl succinate is mainly used in the synthesis of light stabilizers, high-grade coatings, food additives, organic solvents, fungicides, and is also a very important pharmaceutical intermediate.

Since Dicarboxylate are dicarboxylic acid, if the alcohol involved in the reaction is a monol, then one molecule of dicarboxylic acid reacts with two molecules of a monol to produce a molecule of Dicarboxylate 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.