A number of chiral resolutions have been developed to separate the two enantiomers of amphetamine.[206] For example, racemic amphetamine can be treated with d-tartaric acid to form a diastereoisomeric salt which is fractionally crystallized to yield dextroamphetamine.[210] Chiral resolution remains the most economical method for obtaining optically pure amphetamine on a large scale.[211] In addition, several enantioselective syntheses of amphetamine have been developed. In one example, optically pure (R)-1-phenyl-ethanamine is condensed with phenylacetone to yield a chiral Schiff base. In the key step, this intermediate is reduced by catalytic hydrogenation with a transfer of chirality to the carbon atom alpha to the amino group. Cleavage of the benzylic amine bond by hydrogenation yields optically pure dextroamphetamine.[211]
A significant number of amphetamine syntheses feature a reduction of a nitro, imine, oxime, or other nitrogen-containing functional groups.[207] In one such example, a Knoevenagel condensation of benzaldehyde with nitroethane yields phenyl-2-nitropropene. The double bond and nitro group of this intermediate is reduced using either catalytic hydrogenation or by treatment with lithium aluminium hydride (method 5).[208][216] Another method is the reaction of phenylacetone with ammonia, producing an imine intermediate that is reduced to the primary amine using hydrogen over a palladium catalyst or lithium aluminum hydride (method 6).[208]
Amphetamine Synthese Anleitung Pdf Freel
A significant number of amphetamine syntheses feature a reduction of a nitro, imine, oxime or other nitrogen-containing functional group.[149] In one such example, a Knoevenagel condensation of benzaldehyde with nitroethane yields phenyl-2-nitropropene. The double bond and nitro group of this intermediate is reduced using either catalytic hydrogenation or by treatment with lithium aluminium hydride (method 4).[155][156] Another method is the reaction of phenylacetone with ammonia, producing an imine intermediate that is reduced to the primary amine using hydrogen over a palladium catalyst or lithium aluminum hydride (method 5).[156]
A number of chiral resolutions have been developed to separate the two enantiomers of amphetamine.[150] For example, racemic amphetamine can be treated with d-tartaric acid to form a diastereoisomeric salt which is fractionally crystallized to yield dextroamphetamine.[158] Chiral resolution remains the most economical method for obtaining optically pure amphetamine on a large scale.[159] In addition, several enantioselective syntheses of amphetamine have been developed. In one example, optically pure (R)-1-phenyl-ethanamine is condensed with phenylacetone to yield a chiral schiff base. In the key step, this intermediate is reduced by catalytic hydrogenation with a transfer of chirality to the carbon atom alpha to the amino group. Cleavage of the benzylic amine bond by hydrogenation yields optically pure dextroamphetamine.[159] 2ff7e9595c
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