Freebase (chemistry)
Free base (freebase, free-base) refers to the conjugate base (deprotonated) form of an amine, as opposed to its conjugate acid (protonated) form. The amine is usually an alkaloid, such as nicotine, cocaine, morphine, and ephedrine, or derivatives thereof.
Some alkaloids are more stable as ionic salts than as free base. The salts usually exhibit greater water solubility. Common counterions include chloride, bromide, sulfate, phosphate, nitrate, acetate, oxalate, citrate, and tartrate. Ammonium salts formed from the acid-base reaction with hydrochloric acid are known as hydrochlorides. For example, compare the free base hydroxylamine (NH2OH) with the salt hydroxylamine hydrochloride (NH3OH+ Cl−).
Freebasing is a more efficient method of self-administering alkaloids via the smoking route. For example, cocaine hydrochloride decomposes at the high temperatures necessary for smoking. Free base cocaine, in which the cocaine alkaloid is "freed" from the hydrochloride salt, has a melting point of 98 ℃ and is volatile at temperatures above 90 ℃, therefore providing an active drug for smoking. The free base form of an alkaloid is more lipid-soluble and crosses the blood-brain barrier more easily, thus having a faster and stronger "impact" or "kick", which is comparable to intravenous injection. Extraction kits for converting the hydrochloride to the base are commercially available. Freebasing also tends to remove water-soluble impurities and adulterants such as sugars (lactose, sucrose, glucose, mannitol, inositol), which are often added to street cocaine. Cocaine freebase is only slightly soluble in water (1 in 600 of water) as compared to the high solubility of cocaine hydrochloride (1 in 0.5 of water).
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