GB890334A - A process for the production of isohydrazones - Google Patents

Abstract

In the preparation of hydrazine or hydrazine salts, isohydrazones are prepared by reacting a ketone or aldehyde in the vapour phase with gaseous NH3 and gaseous Cl2 and removing NH4Cl and unreacted starting materials from the reaction mixture, the molecular ratio of NH3:Cl2 being greater than 4:1 and that of ketone or aldehyde: Cl2 being greater than 1:1. The reaction is at 60 DEG -100 DEG C. and 0,1-0,3 atm. or up to 1 atm., and the NH3 may be diluted with 0,5-2 mols. inert gas, e.g. N2, per mol. NH3. The NH4Cl is separated from the reaction mixture by a dust separator or by washing with NH4Cl solution. The resulting gases may be cooled to -10 DEG C. to recover the isohydrazone as an aqueous solution, or may be washed with water or aqueous NH3 and the resulting isohydrazone solution boiled to remove dissolved NH3 and ketone or aldehyde. Residual gas may be recycled to the process. The aqueous isohydrazone solution is heated with mineral acid, e.g. H2SO4 or HCl, to yield the hydrazine salt which may be converted to hydrazine by alkali metal hydroxide. Specified aldehydes and ketones, which are volatile without decomposition in vacuo at the highest reaction temperatures, are acetone, methylethyl ketone, diethyl ketone, cyclohexanone, methylisopropyl ketone, ethylpropyl ketone, methylbutyl ketone, acetaldehyde, propionaldehyde, butyraldehyde, and benzaldehyde. Acetone isohydrazone is probably <FORM:0890334/III/1> with a melting point 40 DEG C.ALSO:Isohydrazones are prepared by reacting a ketone or aldehyde in the vapour phase with gaseous NH3 and gaseous Cl2, and removing NH4Cl and unreacted starting materials from the reaction mixture, the molecular ratio of NH3 : Cl2 being greater than 4 : 1 and that of ketone or aldehyde; Cl2 being greater than 1 : 1. The reaction is at 60 DEG C.-100 DEG C. and 0.1-0.3 atmospheres or up to 1 atmosphere, and the NH3 may be diluted with 0.5-2 mols inert gas, e.g. N2, per mol NH3. The NH4Cl is separated from the reaction mixture by a dust separator or by washing with NH4Cl solution. The resulting gases may be cooled to -10 DEG C. to recover the isohydrazone as an aqueous solution, or may be washed with water or aqueous NH3 and the resulting isohydrazone solution boiled to remove dissolved NH3 and ketone or aldehyde. Residual gas may be recycled to the process. Specified aldehydes and ketones which are volatile without decomposition in vacuo at the highest reaction temperatures, are, acetone, methylethyl ketone, diethyl ketone, cyclohexanone, methylisopropyl ketone, ethyl propyl ketone, methylbutyl ketone, acetaldehyde, propionaldehyde, butyraldehyde, and benzaldehyde. Acetone isohydrazone is probably <FORM:0890334/IV (b)/1> with a melting point 40 DEG C.