| 摘要 |
Prodn. of monomethylhydrazine (I) in aq. soln. comprises reaction of chloramine (II) with a 1 mol excess of MeNH2 (III) for a time D1 in aq. medium and oxygen-free atmos., in the presence of a strong base, pref. NaOH, and working up the mixt. of (I) and volatile by-prods. obtd., pref. by stripping followed by distn., to give a conc. aq. soln. of (I). The novelty is that, before the reaction mixt. is worked up, it is then heated to 30-100 (pref. 70-100) deg.C for a time D2 such that D2/D1 is greater than 10 (pref. 50-100), in the absence of oxygen and keeping the pH above 13.5, so that the above by-prods. (esp. methyldiazine) are partly or completely removed. - Process is operated continuously; (II) is produced in aq. basic medium with pH 10-14 (pref. in a NH3/NH4Cl buffer) under oxygen-free atmos., by reaction of ammonia with alkali hypochlorite (pref. NaOCl) at -10 to +10 deg.C. (II) is produced in a first reactor with an inlet for the aq. medium and the reactants and an outlet through which the reaction mixt. is transferred by suitable devices to a sec. reactor, from there to a third reactor in which the extra prodn. stage is carried out, and then to the purificn./concn. stage. The third reactor is a tube reactor fitted with a double mantle which enables circulation of a fluid. On leaving the first reactor, the medium contg. (II) is passed to a mixer which is also charged with (III), and the mixt. thus obtd. is transferred to the sec. reactor which is charged with strong base.
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