Patent GB-594453-A (GB)
Title: Improvements in or relating to organic derivatives of hydrazine
Filed: 1943-02-10
Abstract: Aliphatic dihydrazines containing two hydrazino groups or mono-alkyl or mono-aryl-substituted hydrazino groups each of which is attached to a different methylene, or mono-alkyl substituted methylene group, are prepared by heating an aliphatic dihalide in which the two halogen atoms are attached to different methylene or mono-alkyl-substituted methylene groups with hydrazine or a mono-alkyl or mono-aryl derivative of hydrazine, or by reducing the dinitroso derivative of an aliphatic diurea by means of zinc and an aliphatic acid and hydrolysing the product.  The methylene or substituted methylene groups are preferably linked by a carbon atom or a chain of carbon atoms, but they may be linked by an atom other than carbon or by a chain which includes one or more atoms other than carbon, e.g. an oxygen atom.  It is preferable to heat a solution of the aliphatic dihalide and the hydrazine in a common solvent, e.g. an aqueous lower aliphatic alcohol such as methanol, ethanol or isopropanol.  Considerably more hydrazine than theoretical, e.g. from 6 to 24 molecular proportions of hydrazine for each molecular proportion of the dihalide is preferably employed.  The unreacted hydrazine is removed from the products of reaction by distillation under reduced pressure and excess aqueous hydrochloric acid may then be added to the residue to convert any remaining hydrazine to its dihydrochloride.  The mixture of dihydrochlorides may then be separated by fractional crystallization from methanol or ethanol. The residue remaining after removing unreacted hydrazine may also be dissolved in alcohol containing a little water and a strong base added so as to combine with all the chlorine in the solution.  The free aliphatic dihydrazine so formed may be isolated by fractional distillation under low pressure.  The dihydrazines may also be isolated in the form of their sulphates or by treating the mixture of dihydrochlorides obtained as above with water and benzaldehyde in the cold when the hydrazine benzaldehyde derivative is precipitated while on allowing the filtrate to stand the dihydrazine benzaldehyde derivative separates out.  Unsubstituted alkylene dichlorides react with methyl hydrazine to give polymethylene dimethyl - di - hydrazines of formula: H2N.N(CH3).(CH2)nN(CH3)NH2, ethyl hydrazine gives the corresponding ethyl derivative; phenyl hydrazine, however, gives polymethylene diphenyl dihydrazines of formula: C6H5.NH.NH.(CH2)nNH.NH.C6H5, n in each formula being an integer greater than 1.  Aliphatic diamines may be used as starting material by converting them into the corresponding di-ureas by reaction with a metal cyanate, e.g. sodium cyanate, and an acid.  The diamines may also be heated with urea, preferably in excess and at 130-150 DEG C., to form the di-ureas.  The latter may be converted into their di-nitroso derivatives by the action of a nitrite, preferably sodium or potassium nitrite in the presence of an acid, especially glacial acetic acid, or by treatment with nitrous fumes.  The reduction of the di-nitroso compounds to the disemicarbazides is preferably conducted at 0-20 DEG  C.  Examples of other aliphatic dihydrazines are compounds containing in the chain an oxygen atom, e.g. 2.21-dihydrazino diethyl ether which may be made from 2 : 21-dichloro diethyl ether by the above method.  In examples: hexamethylene dihydrazine dihydrochloride is produced by heating hydrazine hydrate or hydrazine in methanol or ethanol with 1 : 6-dichlorohexane, the unchanged hydrazine is distilled off and any remaining hydrazine precipitated as the dihydrochloride by adding hydrochloric acid or separated by means of benzaldehyde as above, in the latter case the benzaldehyde derivative of hexamethylene dihydrazine is finally steam distilled from dilute hydrochloric acid to decompose it and remove the benzaldehyde.  Free hexamethylene dihydrazine is obtained by refluxing hydrazine hydrate and 1 : 6-dichlorohexane in methanol, removing some unchanged hydrazine by azeotropic distillation with toluene, adding potassium hydroxide with fresh toluene, continuing the distillation, removing the precipitated potassium chloride and finally distilling the filtrate.  In another example, hexamethylene dihydrochloride is obtained by heating hexamethylene diamine and urea at 130-140 DEG  C. to form the di-urea, the latter being converted to the dinitroso compound which is then reduced as above and the product hydrolysed with concentrated hydrochloric acid and separated by means of benzaldehyde.  1 : 4-Dichlorobutane may be used instead of the 1 : 6-dichlorohexane and tetramethylene diamine in place of the hexamethylene diamine.  1 : 5-Dichlorpentane is also specified as a starting material.  According to the Provisional Specification, the residue linking the hydrazino groups may contain one or more aromatic or heterocyclic rings which may form part of the chain linking the hydrazino groups, whether or not they are directly attached to a hydrazino group or may be present as side groups.  It is also stated that substituents on the hydrazino groups may be aralkyl groups, e.g. benzyl, or acyl groups, e.g. formyl, acetyl, benzoyl, and may be attached to either nitrogen atom.  Additional starting materials specified are trimethylene-, enneamethylene- and p-benzylene-di-ureas.