Due to the symmetry of the hydrazine molecule, it does not matter which hydrogen atom is replaced. monomethyl hydrazine, where one of the hydrogen atoms on the hydrazine molecule has been replaced with a methyl group (CH 3).Organohydrazines and their derivatives are numerous, especially when hydrazones are included. Phenylhydrazine was used to study the structure of carbohydrates, because the reaction of the sugar's aldehyde groups lead to well crystallizing phenylhydrazones or osazones. Phenylhydrazine and 2,4-dinitrophenylhydrazine have were used historically in analytical chemistry to detect and identify compounds with carbonyl groups. They react with concentrated sulfuric acid to form violet or dark blue compounds. The corresponding arylhydrazines are solid colorless substances which are insoluble in water and substantially not basic. Tri- or tetrasubstituted aliphatic hydrazines are water-insoluble weakly basic compounds.
Symmetrically disubstituted hydrazines are prepared by reducing nitro compounds under basic conditions or by reducing the azines. Aromatic symmetric disubstituted hydrazines are not soluble in water. In particular, the aliphatic compounds are basic and reducing agents and are soluble in water. Like asymmetrically disubstituted hydrazines, they are liquids, but their boiling points are typically higher. In symmetric disubstituted hydrazines, a hydrocarbon group is bonded to each of the hydrazine nitrogen atoms. Aromatic hydrazines are prepared by reducing aromatic diazonium salts. For the preparation of aliphatic hydrazines, the reaction of hydrazine with alkylating compounds such as alkyl halides is used, or by reduction of nitroso derivatives. Aromatic monosubstituted and asymmetrically disubstituted hydrazines are poorly soluble in water, less basic and weaker reducing agents. Aliphatic monosubstituted and asymmetrically disubstituted hydrazines are very water soluble, strongly alkaline and good reducing agents. Monosubstituted hydrazines and so-called asymmetrically disubstituted hydrazines, where (only) two hydrocarbon groups are bonded to the same nitrogen atom are colorless liquids. Hydrazines belonging to the same group behave similarly in their chemical properties. Hydrazines can be divided into three groups according to the degree of substitution. Tetraphenylhydrazine is formed by the oxidation of diphenylamine with potassium permanganate in acetone.2,4-Dinitrophenylhydrazine is produced by the reaction of 1-chloro-2,4-dinitrobenzene with hydrazine.The reduction of benzenediazonium chloride with tin(II) chloride and hydrochloric acid provides phenylhydrazine.1,1-Dimethylhydrazine is produced by the reduction of N-nitrosodimethylamine.Hydrazines can be considered as derivatives of the inorganic hydrazine (H 2N−NH 2), in which one or more hydrogen atoms have been replaced by hydrocarbon groups. Hydrazines (R 2N−NR 2) are a class of chemical compounds with two nitrogen atoms linked via a covalent bond and which carry from one up to four alkyl or aryl substituents.
0 kommentar(er)
