Carboxylic acid and ester perfume

Carboxylic acid is also known as "organic acid". A general term for an organic compound in which a hydrocarbon group and a carboxyl group are combined, and has a general formula of RCOOH, and is often widely present in nature in the form of an ester. Divided according to the hydrocarbyl structure: 1 aliphatic carboxylic acid: carboxyl group is linked to an aliphatic hydrocarbon group, such as acetic acid CH3COOH. 2 Aromatic carboxylic acid: The carboxyl group is bonded to an aromatic ring, such as benzoic acid C6H5-COOH. 3-cyclic acid: A carboxyl group is bonded to a cyclic hydrocarbon group such as cyclohexanecarboxylic acid. 4 Saturated carboxylic acid: an acid containing a saturated hydrocarbon group such as butyric acid CH3CH2CH2COOH. 5 Unsaturated carboxylic acid: an acid containing an unsaturated hydrocarbon group such as CH2=CHCOOH. It is divided into a monobasic acid, a dibasic acid and a polybasic acid according to the number of carboxyl groups contained in the molecule. There are other substituent groups in the hydrocarbon group called "substituted carboxylic acids". The saturated monocarboxylic acid contains a liquid of one to nine carbon atoms, a solid having more than ten carbon atoms, and both an aromatic carboxylic acid and a saturated dicarboxylic acid are solids. Carboxylic acids have a weak acidity and are used in large quantities for the production of esters, acid chlorides, amides and anhydrides, and the reduction of carboxylic acids gives the corresponding alcohols. Many carboxylic acids are widely used in dyes, rubbers, pharmaceuticals, perfumes, daily chemicals, light industry and the like. Ester perfumes are ester compounds synthesized from carboxylic acids and alcohols and are a very important class of perfumes. Depending on the starting materials used in the synthesis, it can be roughly classified into: aliphatic carboxylic acid esters, aromatic carboxylic acid esters, carboxylic acid esters containing an olefinic or alkyne unsaturated bond, and other esters. The characteristics of the ester perfume are: The carboxylate can be considered as the product of the substitution of the hydroxyl group of the acid with an alkoxy group, since the hydroxyl group of the carboxyl group can be substituted by one or more alkoxy groups, so that a monoester, a diester or a polyester can be formed. . Further, the alcohol may have a plurality of hydroxyl groups, and thus the alkoxy group may form a monocarboxylic acid or a polycarboxylic acid ester with one or more carboxyl groups. The aroma, aroma type, strength and characteristics of the ester are related to the structure of the ester. The esters of lower carboxylic acids and lower alcohols are generally volatile liquids with aromas of flowers, fruits and grasses. An ester of a lower carboxylic acid and a lower terpene alcohol with a floral aroma. Esters with aryl groups, most with floral aroma. The esters of aromatic acids and aromatic alcohols, although not strong in aroma, have a high boiling point and a long lasting aroma. Ester perfumes are widely distributed in nature, and are found in roots, stems, leaves, fruits, seeds, bark, and flowers of plants; they are also present in certain animal secretions. Synthetic ester fragrances are more. Since the synthesis of esters is easy, the source of raw materials is wide, and the synthetic esters are many types and inexpensive, they are widely used. Fatty acid ester perfumes play an important role in the perfume industry. They are characterized by many varieties, easy synthesis and low price. They are widely used in daily flavors, food flavors and industrial flavors. The main processes include esterification of an alcohol with a fatty acid, reaction of an alcohol with an acid anhydride, reaction of an alcohol with an acid chloride, transesterification, and reaction of a carboxylate with an alkyl halide. Aromatic ester perfumes mainly include benzoic acid esters (benzoin ester), phenylacetate, cinnamate, and salicylate. The synthesis methods mainly include esterification reaction of an alcohol with an aromatic acid, reaction of an alcohol with benzoyl chloride, exchange of an ester, and reaction of an aromatic acid salt with an alkyl halide. They play an important role in daily fragrances and food flavors.