Method for the continuous synthesis of monoalkyl-hydrazines with a functionalised alkyl group

A method for the continuous synthesis of a monoalkylhydrazine of formula

• NH2—NH—R (I)
• in which R is selected from the group consisting of C2-C6 alkenyl radical, C2-C6 alkynyl radical, C1-C5 linear alkyl radical containing at least one imine function (—C═N—), and linear or branched C1-C6 alkyl radical carrying at least one functional group selected from the group consisting of OH, C1-C6 alkoxy, C═NH, C—N, phenoxy, COOH, COO—(C1-C6 alkyl), phenyl or NR3R4, with R3 and R4 each representing independently a C1-C6 alkyl radical or forming a C2-C6 ring, wherein the method comprises the following successive steps:
• (a) synthesizing the monoalkylhydrazine of formula I in a suitable reactor while causing to react in an alkaline medium and at a temperature in the range between 25 and 45° C. a monochloramine with an anhydrous amine of formula
• NH2—R (II)
• R having the same significance as for formula I;
• then
• (b) demixing the solution obtained following step a in an organic phase and an aqueous phase by the addition of anhydrous sodium hydroxide under cooling so that the temperature of the demixing medium does not exceed the boiling points of the compounds;
• and
• (c) isolating from the organic phase thus obtained the monoalkylhydrazine of formula I.