<unk>  is a primary amine, the amino-group being attached to a benzene ring through a two-carbon, or ethyl group. It is a colourless liquid at room temperature that has a fishy odor, and is soluble in water, ethanol and ether. Its density is 0.964 g/ml and its boiling point is 195 °C. Upon exposure to air, it combines with carbon dioxide to form a solid carbonate salt.<unk>  is strongly basic, pKb = 4.17 (or pKa = 9.83), as measured using the HCl salt, and forms a stable crystalline hydrochloride salt with a melting point of 217 °C. Substituted derivatives Substituted<unk> s are a chemical class of organic compounds based upon the<unk>  structure; the class is composed of all the derivative compounds of<unk>  which can be formed by replacing, or substituting, one or more hydrogen atoms in the<unk>  core structure with substituents. Many substituted<unk> s are psychoactive drugs, which belong to a variety of different drug classes, including central nervous system stimulants (e.g., amphetamine), hallucinogens (e.g., 2,5-dimethoxy-4-methylamphetamine), entactogens (e.g., 3,4-methylenedioxyamphetamine), appetite suppressants (e.g. phentermine), nasal decongestants and bronchodilators (e.g., pseudoephedrine), antidepressants (e.g. bupropion), antiparkinson agents (e.g., selegiline), and vasopressors (e.g., ephedrine), among others. Many of these psychoactive compounds exert their pharmacological effects primarily by modulating monoamine neurotransmitter systems; however, there is no mechanism of action or biological target that is common to all members of this subclass. Numerous endogenous compounds – including hormones, monoamine neurotransmitters, and many trace amines (e.g., dopamine, norepinephrine, adrenaline, tyramine, and others) – are substituted<unk> s. Dopamine is simply<unk>  with a hydroxyl group attached to the 3 and 4 position of the benzene ring. Several notable recreational drugs, such as MDMA (ecstasy), methamphetamine, and cathinones, are also members of the class. All of the substituted amphetamines are<unk> s, as well. Pharmaceutical drugs that are substituted<unk> s include phenelzine, phenformin, and fanetizole, among many others. Synthesis One method for preparing β-phenethylamine, set forth in J. C. Robinson and H. R. Snyder's Organic Syntheses (published 1955), involves the reduction of benzyl cyanide with hydrogen in liquid ammonia, in the presence of a Raney-Nickel catalyst, at a temperature of 130 °C and a pressure of 13.8 MPa. Alternative syntheses are outlined in the footnotes to this preparation. A much more convenient method for the synthesis of β-phenethylamine is the reduction of ω-nitrostyrene by lithium aluminum hydride in ether, whose successful execution was first reported by R. F. Nystrom and W. G. Brown in 1948.<unk>  can also be produced via the cathodic reduction of benzyl cyanide in a divided cell. thumb Assembling<unk>  structures for synthesis of compounds such as epinephrine, amphetamines, tyrosine, and dopamine by adding the beta-aminoethyl side chain to the phenyl ring is possible. This can be done via Friedel-Crafts acylation with N-protected acyl chlorides when the arene is activated, or by Heck reaction of the phenyl with N-vinyloxazolone, followed by hydrogenation, or by cross-coupling with beta-amino organozinc reagents, or reacting a brominated arene with beta-aminoethyl organolithium reagents, or by Suzuki cross-coupling. Detection in body fluids Reviews that cover attention deficit hyperactivity disorder (ADHD) and<unk>  indicate that several studies have found abnormally low urinary<unk>  concentrations in ADHD individuals when compared with controls. In treatment-responsive individuals, amphetamine and methylphenidate greatly increase urinary<unk>  concentration. An ADHD biomarker review also indicated that urinary<unk>  levels could be a diagnostic biomarker for ADHD. Thirty minutes of moderate- to high-intensity physical exercise has been shown to induce an increase in urinary phenylacetic acid, the primary metabolite of<unk> . Two reviews noted a study where the mean 24 hour urinary phenylacetic acid concentration following just 30 minutes of intense exercise rose 77% above its base level; the reviews suggest that<unk>  synthesis sharply increases during physical exercise during which it is rapidly metabolized due to its short half-life of roughly 30 seconds. In a resting state,<unk>  is synthesized in catecholamine neurons from -phenylalanine by aromatic amino acid decarboxylase at approximately the same rate as dopamine is produced. Monoamine oxidase deaminates primary and secondary amines that are free in the neuronal cytoplasm but not those bound in storage vesicles of the sympathetic neurone. Similarly, β-PEA would not be deaminated in the gut as it is a selective substrate for MAO-B, which is not found in the gut. Brain levels of endogenous trace amines are several hundred-fold below those for the classical neurotransmitters noradrenaline, dopamine, and serotonin, but their rates of synthesis are equivalent to those of noradrenaline and dopamine and they have a very rapid turnover rate. Endogenous extracellular tissue levels of trace amines measured in the brain are in the low nanomolar range. These low concentrations arise because of their very short half-life. Because of the pharmacological relationship between<unk>  and amphetamine, the original paper and both reviews suggest that<unk>  plays a prominent role in mediating the mood-enhancing euphoric effects of a runner's high, as both<unk>  and amphetamine are potent euphoriants. Skydiving has also been shown to induce a marked increase in urinary<unk>  concentrations.
Phenethylamine
Chlorphenamine
Methoxyphenamine
Phenoxyethanol
Pseudophenmetrazine
Trimethobenzamide
Carctol
Triprolidine