Reaction of halogen compounds with ammonia derivatives

Reaction of halogen compounds with ammonia derivatives a. Alkylation 

Treatment of ammonia or primary or secondary amines with alkyl halides almost always leads to a mixture of all the higher alkylation stages. Using an excess of the halide can thus afford the quaternary salt in one stage provided the formation of the hydrohalides is suppressed by addition of a base nevertheless, alkylation of a tertiary base is preferable for preparation of quaternary salts. 

It is essential to use a sufficient excess (at least ten-fold) of ammonia if primary amines are to be obtained in reasonable yield the technique of working in liquid ammonia, proposed by von Braun,437 also provides this excess. The ease with which the components can be separated out of the inevitable mixture naturally increases with increasing size of the alkyl group in the halide used, since this increases the differences in boiling point of the free bases. For this reason this method does not come into consideration for the first few members of the homologous monoalkylamines but it also cannot be used for alkylamines containing very long chains as the requisite halides are then insoluble in liquid ammonia.438 

Westphal and Jerchel439 used alcoholic ammonia in a sealed tube but obtained mainly the secondary amine. Butylamine can be obtained in 47% yield by a somewhat involved procedure from butyl bromide and alcoholic ammonia at room temperature without the use of increased pressure.440 

A series of ring-substituted primary phenethylamines has been prepared in 70-80% yield by a similar method a solution of the requisite phenethyl bromide (15 g) in ethanol (500 ml) is saturated with ammonia at 5° and set aside for 5-8 days.441 

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