Anhydrides of carboxylic acids - are products of dehydration of the molecules.These are characterized by isomerism biosoedineny radicals.When naming anhydrides often relies on historical range (e.g., acetic anhydride, maleic anhydride, etc.).During the addition of carboxylic acids dehydrating agents (typically phosphorus oxide) is their dehydration, resulting in the formation of carboxylic acid anhydrides.
Acetic anhydride: getting
This compound can be washed in several ways.For its synthesis most commonly used phosphorus oxide, which is a very strong dehydrating agent.There are also other methods for the synthesis of the anhydride.For example, acetic anhydride can be obtained by exposure of phosphate anhydride acetate acid.During cooling was added dropwise a single particle to a single particle SN3SOS1 dewatered and carefully dried acid-sodium acetate.The resulting mixture was heated moderately and the synthesized acetic anhydride is distilled off in a sand bath and then purified by distillation.As a result of work get strong-smelling liquid acid acetate.
acetic anhydride, and low-molecular substances - liquid with a sharp odor, practically insoluble in water, readily soluble in many organic substances.It should be noted that the higher carboxylic acid anhydrides (especially limiting) - solids odorless.The temperature of the boil significantly higher than the corresponding carboxylic acids.
Acetic anhydride: chemical properties
This compound is commonly used for many representatives of different classes of organic compounds by methods of organic synthesis.The interaction of anhydrides with two molecules of water to give the corresponding acid.
Amonoliz anhydrides leads to the formation of amides and ammonium salts of the corresponding carboxylic acids.The reactions used for obtaining alkoliza anhydride esters.
Acetal anhydride is used as the dehydrating and acetylating agent in the production process atsetiltselyulozy, vinyl acetate, medicines, dimethylacetamide, colorants, aromatic substances, etc.Acetate aldehyde irritate the respiratory tract, eyes, and cause skin burns.
acetate obtained due to the action on the cellulose acetate anhydride in the presence of a catalyst (acid sulphate).Incomplete acetylation of mono- and diacetates obtained pulp.Di- and triacetates used in the production of acetate silk.For this purpose they are dissolved in a mixture of acetone and ethanol (85:15) or pure acetone.A viscous solution which is forced through a special filter.Thin strips of the solution dry up and turn into yarns, which are used for the production of different types of yarn of synthetic fibers.
used for industrial purposes and other forms of anhydrides.Maleic anhydride - crystalline substance, well soluble in water and in acetone, melts at 52,85 ° C.Typically, this material is prepared from maleic acid.It is used in the production of pesticides, polyester and alkyd resins.Phthalic anhydride is obtained as a result of oxidation of naphthalene.The latter is used for the synthesis of growth factors, insecticides, as well as some medications.Phthalic anhydride - crystalline solid with a melting point of 128 ° C.This anhydride is used for phenolphthalein (indicator and Drug Administration).This anhydride is used for the production of repellents (dimethyl phthalate).
