Rhodium
(Chief Bee)
07-30-02 06:44
No 338805
      P2P methylimine synth + imine grignard
(Rated as: excellent)
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Patent GB702985

Phenylacetone Methylimine (Example 5)

To 31g (1 mole) of liquid methylamine freebase (bp -6C) in a flask fitted with a dry ice reflux condenser was added over a period of one hour with rapid stirring 134g (1 mole) of phenylacetone. STirring was continued for one hour at room temp, when 25g of potassium hydroxide pellets were added. After standing overnight at 5C, the water removed by the KOH indicated that the reaction had gone to 70% completion. The organic layer was separated and 7g of potassium hydroxide added and again allowed to stand overnight at 5C. The reaction, by water removal, had gone to 90% completion.

Separation of the organic layer and distillation 1 mmHg in a nitrogen atmosphere over 4g of potassium hydroxide yielded a colorless liquid product having the following properties: bp 63-66C/1mmHg, d20 0.9631, nD20 1.5270.

Methamphetamine (Example 12)

20.6g of phenylacetone methylimine was dissolved in 45ml ethyl acetate, and to this was added 10g of 5% Pd/C and the mixture reduced by the addition of hydrogen until 1.39 moles was absorbed. The catalyst was removed by filtration and the product distilled, collecting methamphetamine at 58-61.5C at 1.1 mmHg. The picrate salt had a mp of 123-124C.

The patent also describes the preparation of the methylimine of acetone, and its reaction with benzylmagnesium chloride to form Mephentermine (N-methyl-phentermine, N,alpha-dimethylamphetamine).