Page 68 - phytochemistry II -pharmD general

hydrolysis
Cocaine ⎯⎯⎯⎯→ ecgonine + benzoic acid + methanol

Cocaine HCl

It is the official salt in B.P. 2008 and E.P. 84.

Cocaine HCl is readily soluble in water (1:0.5), alcohol, chloroform (1:15) but
insoluble in ether or petroleum ether.

Uses of cocaine

Local anaesthetic in small operations. Synthetic local anaesthetics are now
preferable than cocaine.

1- Preparation of crude total alkaloids from natural source

In case of Peruvian coca, the powdered leaves are moistened with sodium
carbonate and extraction is followed by petroleum ether (150-220oC). The organic
extract is then shaken with dil. hydrochloric acid. The aqueous layer is
concentrated where ecgonine esters crystallize out as hydrochlorides.

In case of Java leaves: it is extracted with benzene after alkalinzation with
sodium carbonate. The benzene extract is shaken with dil. sulphuric acid, the acid
extract is then rendered alkaline with sodium carbonate, and extracted with ether.
The ether extract, after dehydration over anhydrous sodium sulphate is distilled to
yield the total crude alkaloids.

2- Partial synthesis from crude natural alkaloids

Java leaves containing cocaine and cinnamyl cocaine are hydrolyzed
completely to ecgonine by boiling with dil. excess HCl. On pouring into water,
truxillic acid is precipitated. By filtration then concentration of the supernatant layer,
ecgonine HCl is crystallized out. The separated crystals are treated with sodium
carbonate to set free the base and extracted with dil. alcohol. After evaporation of
the alcohol, ecgonine is then benzoylated by digestion with benzoic anhydride for
one hour (excess benzoic anhydride and benzoic acid are removed by extraction

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