Cocaine residual solvents

Table 6.4 Residual Solvents in Cocaine Exhibits Percents Occurrence ...

Cocaine can be extracted from the leaves with almost any organic solvent. Moisten the dried, powdered leaves with Na carbonate solution and extract with cold benzene or petroleum ether. Extract the organic solution with small amounts of dilute sulfuric acid and basify the extract with Na carbonate (the alkaloids precipitate). Dissolve the precipitate in ether, separate the ether from the aqueous Na carbonate and dry and evaporate in vacuum the ether. Dissolve the residue in methanol and heat with sulfuric acid or methanol-HCl dilute with water and extract with CHC13. Concentrate and neutralize the aqueous layer and cool to precipitate methylecgonine sulfate, which is converted to cocaine in one step. The alkaloids can also be extracted directly from the powder with dilute sulfuric acid. 

The extraction process can be performed in acidic conditions which produces the cocaine as its hydrochloride salt. Alkaline conditions will produce a lipophilic "free base" which can be extracted with a nonpolar solvent like ether. The ether can be volatilized with heat and the free base smoked, snorted, injected, or eaten. The salt form cannot be smoked. Cocaine paste, not common in the U.S. is a kerosene extract which may contain 20-90% cocaine sulfate. Crack is the result of free-basing with baking soda (sodium bicarbonate). The residual fillers and other impurities... 

Coca paste production Coca leaves are mixed with calcium hydroxide (lime) and water. The mixture is crushed and stirred in a hydrocarbon solvent, usually kerosene. The extracted coca leaf residue is removed and the kerosene extracted with acidified water. The cocaine alkaloids are extracted into the aqueous layer and coca paste is precipitated by the addition of base. This paste contains crude cocaine as well as a mixture of inorganic salts. Alternatively, the leaves can be crushed in dilute sulfuric acid, extracted with kerosene, and the aqueous layer made alkaline with ammonia or a similar method to precipitate the alkaloids. 

In a report of the United Nations Commission of enquiry on the Coca leaP it was observed that no true crystals of cocaine were obtained with platinic chloride on the residue from the ether-light petroleum when dissolved in dilute acid. The crystals which were obtained were hybrids, not characteristic of cocaine. The difficulty was overcome by shaking the mixed solvent extract with 10 ml of a 2 per cent aqueous solution of potassium permanganate. After separation of the layers the permanganate was discarded and the organic layer treated as in the original method. 

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