Amphetamines

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Amphetamines are part of a class of drugs called stimulants that

affect the central nervous system. It is also known as

1-methyl-2-phenethylamine, 1-phenyl-2-aminopropane, and Benzedrine. It

is made up of a 50/50 mixture of the l and d isomers. The l isomer

affects the body, and the d isomer affects the brain. It boils at

200ºC and is soluble in alcohol and ether, slightly soluble in water.

It was first created in Germany in 1887. In the 1930s and 40s

amphetamine was used in the treatment of asthma, depression, obesity,

and narcolepsy. Amphetamine's chemical structure is very similar to

the neurotransmitter Adrenaline.

[IMAGE]Chemical structure of Amphetamine,

C H CH CH(NH ) CH

Method of Preparation

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There are many ways of creating amphetamines. One way is to take two

mols, for example, 270 grams, of racemic amphetamine base to react

with one mol (150 grams) of d-tartaric acid, forming a dl-amphetamine

d-tartrate, or a neutral salt. The neutral salt obtained is dissolved

by the addition of about 1 litre, of ethanol, and heating to boiling

point. The solution then must be cooled to room temperature with

occasional stirring to effect crystallisation. The crystals are

filtered out and will be found to contain laevo enantiomorph, which is

the left of a pair of crystals that are a mirror image of each other.

It is then recrystallised and the predominance of the l-enantiomorph

is found to be increased and the process is repeated until no further

change is effected and a concentration of 8 grams per 100 cc of

aqueous solution is obtained. Finally the product obtained is

l-amphetamine d-tartrate. d-amphetamine may be recovered from this by

the addition of tartaric acid for the formation of acid tartrates and

separation of d-amphetamine d-bitartrate by crystallisation.

Properties and Chemical Reactions of Amphetamines

Amphetamines vary from a white to brown colour, though sometimes a

purple or orange. It comes in the form of powder, tablets, capsules,

crystals or a red liquid. They have a strong smell, and bitter taste.

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