Ester

Esters are formed by the esterification of an inorganic or organic acid with an alcohol to remove water. The ester can also be formed by reacting an alcohol or a phenol with an acid halide or anhydride, an alcohol and an ketone, and a free acid with an aliphatic diazonium derivative. The hydrogen on the α-carbon in the ester molecule loses one molecule of alcohol with another ester under basic conditions to form a β-ketoester, which is called an ester condensation reaction. For example, ethyl acetate is subjected to ester condensation to form ethyl acetoacetate. This reaction is extremely important in organic synthesis. The name of the ester is based on the name of the corresponding carboxylic acid and alcohol or phenol, such as "an acid ester." The cyclic ester is called lactone (Lactone). The chemical properties of the ester are similar to those of the acid halide anhydride, which are prone to hydrolysis, alcoholysis and aminolysis. The lower esters are aromatic, volatile, colorless liquids, and the higher esters are solids. Esters are important solvents and synthetic raw materials, and some esters are themselves pharmaceuticals. Depending on the type of acid, esters can be classified into inorganic acid esters and organic acid esters, the former such as methyl hydrogen sulfate CH3OSO3H and the latter such as ethyl acetate CH3COOCH2CH3; depending on the type of hydrocarbon group, esters can be further divided into fatty esters and aromatic esters and rings. Ester, ethyl acetate is a fatty ester, phenyl acetate is an aromatic ester, and methyl decanoate is a cyclic ester. The esters are generally neutral colorless liquids, and the esters of aliphatic hydrocarbons and saturated alcohols have a fruity aroma, are soluble in water, and some are hardly soluble in water. Some esters have a low flash point and are often flammable. Vapor can be absorbed through the respiratory tract and liquid esters can be absorbed through the skin. After absorption, it is dissolved in plasma, partially excreted in the lungs and kidneys, partially hydrolyzed and transferred to normal metabolic processes. Most of the ester compounds are highly toxic and highly toxic, and many of them are non-toxic and moderately toxic. There are 38 esters in the tea aroma component. Mainly: 1 fatty ester: from alcohol and fat, such as ethyl acetate, hexenyl hexenoate. 2 Aromatic esters: formed from alcohols and aromatic acids, such as cis-3-hexenyl benzoate. 3-cyclic ester: formed from an alcohol and a cyclic acid, such as methyl jasmonate. Esters are generally neutral and hydrolyze to form alcohols and acids. Low carbon numbers are usually scented liquids, and high carbon numbers are water-insoluble liquids and solids.