Crack-cocaine

Crack cocaine, also known simply as crack, is a free base form of cocaine that can be smoked. It offers a short but intense high to smokers. The Manual of Adolescent Substance Abuse Treatment calls it the most "addictive" (effective) form of cocaine. Crack cocaine is commonly used as a recreational drug. Crack first saw widespread use in primarily impoverished inner city neighborhoods in New York, Los Angeles, and Miami in late 1984 and 1985; its rapid increase in use and availability is sometimes termed as the "crack epidemic".

In purer forms, crack rocks appear as off-white nuggets with jagged edges, with a slightly higher density than candle wax. Purer forms of crack resemble a hard brittle plastic, in crystalline form (snaps when broken). A crack rock acts as a local anesthetic (see: cocaine), numbing the tongue or mouth only where directly placed. Purer forms of crack will sink in water or melt at the edges when near a flame (crack vaporizes at 90 °C, 194 °F).

Crack cocaine as sold on the streets may be adulterated or "cut" with other substances mimicking the appearance of crack cocaine to increase bulk. Use of toxic adulterants such as levamisole has been documented.

Sodium bicarbonate (NaHCO₃, common baking soda) is a base used in preparation of crack, although other weak bases may substitute for it. The net reaction when using sodium bicarbonate is

With Ammonium bicarbonate:

With Ammonium carbonate:

Crack cocaine is frequently purchased already in rock form, although it is not uncommon for some users to "wash up" or "cook" powder cocaine into crack themselves. This process is frequently done with baking soda (sodium bicarbonate), water, and a spoon. Once mixed and heated, the bicarbonate reacts with the hydrochloride of the powder cocaine, forming free base cocaine and carbonic acid (H₂CO₃) in a reversible acid-base reaction. The heating accelerates the degradation of carbonic acid into carbon dioxide (CO₂) and water. Loss of CO₂ prevents the reaction from reversing back to cocaine hydrochloride. Free base cocaine separates as an oily layer, floating on the top of the now leftover aqueous phase. It is at this point that the oil is picked up rapidly, usually with a pin or long thin object. This pulls the oil up and spins it, allowing air to set and dry the oil, and allows the maker to roll the oil into the rock-like shape.

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