Cocaine is an alkaloid and a member of a broad group of plant substances that also includes nicotine, caffeine, and morphine. The chemical name for cocaine is benzoyl-methyl-ecgonine.[2,3] Cocaine’s chemical structure consists of three parts: a lipophilic group, a hydrophilic group, and an aliphatic group, which joins the first two groups (see image).
On the street, cocaine comes in either of two forms: hydrochloride salt or "base." The hydrochloride salt (powdered) form of cocaine can be administered intranasally (i.e. snorted). It can also be dissolved in water and injected. The "base" forms of cocaine include any forms that are not neutralized by an acid to make the hydrochloride salt. Depending on the method of production, the base forms are called "freebase" or "crack."
The medical literature is often ambiguous when differentiating between "freebase" and "crack," which are actually the same chemical form of cocaine. This notwithstanding, crack and freebase are made using different techniques. Freebase is produced by dissolving cocaine hydrochloride in water, adding a base like ammonia, and then adding a solvent, typically ether. The cocaine base is dissolved by the ether and is extracted by evaporation. There is a chance that the ether, which is highly volatile, may remain in the mixture and cause burns. Crack, on the other hand, is produced by dissolving cocaine hydrochloride in water, mixing it with ammonia or sodium bicarbonate (baking soda), and heating this mixture to remove hydrochloride.[5-7] The remaining product is a soft mass that becomes hard when it dries. The name “crack” comes from the crackling sound made when the mixture is smoked.[6,7]
In its base form, cocaine can be smoked because it melts at a much lower temperature (80 °C) than cocaine hydrochloride (180 °C). With the increased prevalence of crack, which is made by a simpler and less dangerous process, the use of "freebase" has declined. Although crack is typically smoked, some users dissolve it with lemon juice and inject it.