metabolites including norpropylhexedrine, cyclohexylacetoxime, cis- and trans-4-hydroxypropylhexedrine. Chemistry Freebase propylhexedrine is a volatile, oily liquid at room temperature. The slow evaporation of freebase propylhexedrine allows it to be administered via inhalation. As an amine, it can easily be protonated to form various salts, such as propylhexedrine hydrochloride, propylhexedrine citrate, or propylhexedrine acetate, depending on the acid used. These salts are stable, clear to off-white crystalline substances that readily dissolve in water. Propylhexedrine is structurally similar to phenylethylamines, with the only structural difference being the substitution of an alicyclic cyclohexyl group for the aromatic phenyl group of phenethylamine. Propylhexedrine is not an amphetamine, nor even a phenethylamine, but instead can be referred to as a cycloalkyl amine, or more specifically a cyclohexylethylamine being the N,a-dimethyl derivative of 2-cyclohexylethylamine. Propylhexedrine is a chiral compound (the α-carbon is chiral), and the active ingredient contained in Benzedrex inhalers is racemic (RS)-propylhexedrine as the free base. (S)-Propylhexedrine, also known as levopropylhexedrine, is believed to be the more biologically active isomer of the two. The dextrorotatory counterpart, which is mainly unused, is dextropropylhexedrine. (S)-Propylhexedrine can be synthesized from dextromethamphetamine. Synthesis Propylhexedrine can be synthesized starting with cyclohexylacetone in a similar fashion to the phenylacetone synthesis of methamphetamine. However, more commonly propylhexedrine is prepared by reacting methamphetamine with Adams' catalyst, reducing methamphetamine's aromatic ring to a cyclohexyl moiety. Society and culture Legal Status On the 4th of April 1988, propylhexedrine was designated a controlled substance (Schedule V) in the United States. This was done to satisfy U.S. compliance with an international treaty. However, in 1991 this action was reversed and propylhexedrine was removed from control under the Controlled Substances Act, based on the opinion of the Drug Enforcement Administration that propylhexedrine did not warrant control. The substance has remained unregulated under the Controlled Substances Act in the United States ever since. The drug was formerly a Class C controlled drug in the United Kingdom, but was legalized in 1995. Recreational use Propylhexedrine is used recreationally in a manner similar to drugs of the amphetamine class. Users report a high similar to other amphetamines, but often more euphoric. Compared to both amphetamine and methamphetamine, propylhexedrine has a much shorter duration of action. This is generally considered undesirable by recreational users. Additionally, propylhexedrine products are manufactured using delivery devices such as sub-recreational-dosage inhalers. This makes it very difficult to consume recreational doses via non-oral routes of administration, which further