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Piperazine is freely soluble in water and ethylene glycol, but insoluble in diethyl ether. It is a weak base with two pK b 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.
Reaction of the lactam-derived enol phosphates 4 of 2,5-diketopiperazines with palladium catalyzed reactions (reduction, Suzuki and Stille cross-coupling reactions) enables the synthesis of a range of functionalised 1,4-dihydropyrazines 5 which can be aromatized to 1,4-pyrazines 6 in the presence of acid.
In the Staedel–Rugheimer pyrazine synthesis (1876), 2-chloroacetophenone is reacted with ammonia to the amino ketone, then condensed and then oxidized to a pyrazine. [5] A variation is the Gutknecht pyrazine synthesis (1879) also based on this selfcondensation , but differing in the way the alpha-ketoamine is synthesised.
A diketopiperazine (DKP), also known as a dioxopiperazine or piperazinedione, is a class of organic compounds related to piperazine but containing two amide linkages. DKP's are the smallest known class of cyclic peptide. [1] Despite their name, they are not ketones, but amides.
Aminoethylpiperazine (AEP) is a derivative of piperazine. This ethyleneamine contains three nitrogen atoms; one primary, one secondary and one tertiary. It is a corrosive organic liquid and can cause second or third degree burns. Aminoethylpiperazine can also cause pulmonary edema as a result of inhalation. It is REACH and TSCA registered. [1]
N-Methylpiperazine is a common building block used in organic synthesis. [2] For example, N-methylpiperazine is used in the manufacture of various pharmaceutical drugs including cyclizine, [3] meclizine, and sildenafil. The lithium salt, lithium N-methylpiperazide, is used as a reagent in organic synthesis for protection of aryl aldehydes. [4]
Terazosin synthesis: [6] Reaction of piperazine with 2-furoyl chloride followed by catalytic hydrogenation of the furan ring leads to 2 . This, when heated in the presence of 2-chloro-6,7-dimethoxyquinazolin-4-amine ( 1 ) undergoes direct alkylation to terazosin ( 3 ).
Benzylpiperazine (BZP) is a substance often used as a recreational drug and is known to have euphoriant and stimulant properties. Several studies conducted between 2000 and 2011 found that the effects of BZP are similar to amphetamine, although BZP's dosage is roughly 10 times higher by weight.