Piperazine () is an organic compound that consists of a six-membered ring containing two nitrogen atoms at opposite positions in the ring. Piperazine exists as small alkaline deliquescent crystals with a saline taste. The piperazines are a broad class of chemical compounds, many with important pharmacological properties, which contain a core piperazine functional group. Origin and naming Piperazines were originally named because of their chemical similarity with piperidine, part of the structure of piperine in the black pepper plant (Piper nigrum). The -az- infix added to "piperazine" refers to the extra nitrogen atom, compared to piperidine. It is important to note, however, that piperazines are not derived from plants in the Piper genus. Chemistry Piperazine is freely soluble in water and ethylene glycol, but insoluble in diethyl ether. It is a weak base with two pKb of 5.35 and 9.73 at 25 °C.; the pH of a 10% aqueous solution of piperazine is 10.8–11.8. Piperazine readily absorbs water and carbon dioxide from the air. Although many piperazine derivatives occur naturally, piperazine itself can be synthesized by reacting alcoholic ammonia with 1,2-dichloroethane, by the action of sodium and ethylene glycol on ethylene diamine hydrochloride, or by reduction of pyrazine with sodium in ethanol. A form in which piperazine is commonly available industrially is as the hexahydrate, C4H10N2. 6H2O, which melts at 44 °C and boils at 125–130 °C. Two common salts in the form of which piperazine is usually prepared for pharmaceutical or veterinary purposes are the citrate, 3C4H10N2.2C6H8O7 (i.e. containing 3 molecules of piperazine to 2 molecules of citric acid), and the adipate, C4H10N2.C6H10O4 (containing 1 molecule each of piperazine and adipic acid). Industrial production Piperazine is formed as a co-product in the ammoniation of 1,2-dichloroethane or ethanolamine. These are the only routes to the chemical used commercially. The piperazine is separated from the product stream, which contains ethylenediamine, diethylenetriamine, and other related linear and cyclic chemicals of this type. As an anthelmintic Piperazine was marketed by Bayer as an anthelmintic in the early 20th century, and was featured in print ads alongside other popular Bayer products at the time, including heroin. In fact, a large number of piperazine compounds have an anthelmintic action. Their mode of action is generally by paralysing parasites, which allows the host body to easily expel the invasive organism. The neuromuscular effects are thought to be caused by blocking acetylcholine at the myoneural junction. This