7 m MEA. Given that typical amine-based absorption processes run at temperatures from 45 °C to 55 °C, the capabilities of piperazine are well within the bounds of and thus favored for carbon capture. Piperazine can be thermally regenerated through multi-stage flash distillation and other methods after being used in operating temperatures up to 150 °C and recycled back into the absorption process, providing for higher overall energy performance in amine gas treating processes. The advantages to using concentrated piperazine (CPZ) as an additive had been confirmed through, for example, three pilot plants in Australia that are operated by CSIRO. This program was launched to explore remedies to the high costs of post-combustion carbon capture, and the results were positive. Using CPZ, which is more reactive and thermally stable than standard MEA solutions, capital and compression (energy) costs were lowered through size reductions in absorber columns and solvent regeneration at higher temperatures. Chemistry The amine groups on piperazine react readily with carbon dioxide to produce PZ carbamate at a low loading (mol CO2/equiv PZ) range and PZ bicarbamate at an operating range of 0.31-0.41 mol CO2/equiv PZ, enhancing the rate of overall CO2 absorbed under operating conditions (refer to Figure 1 below). Due to these reactions, there is limited free piperazine present in the solvent, resulting in its low volatility and rates of precipitation as PZ-6H2O. Piperazine derivatives as drugs Many currently notable drugs contain a piperazine ring as part of their molecular structure. Examples include: Antianginals Ranolazine Trimetazidine Antidepressants Amoxapine Befuraline Buspirone Flesinoxan Gepirone Ipsapirone Nefazodone Piberaline Tandospirone Trazodone Vilazodone Vortioxetine Zalospirone Antihistamines Buclizine Cetirizine Cinnarizine Cyclizine Hydroxyzine Levocetirizine Meclizine Niaprazine Antiserotonergics EGIS-7625 Antipsychotics Typical Flupentixol Fluphenazine Perphenazine Prochlorperazine Thiothixene Trifluoperazine Zuclopenthixol Atypical Amperozide Aripiprazole Clozapine Lurasidone Olanzapine Perospirone Ziprasidone Quetiapine Cariprazine Recreational Drugs 4-Bromo-2,5-dimethoxy-1-benzylpiperazine (2C-B-BZP) 1-Benzylpiperazine (BZP) 2,3-Dichlorophenylpiperazine (DCPP) 1,4-Dibenzylpiperazine (DBZP) 4-Methyl-1-benzylpiperazine (MBZP) 3-Chlorophenylpiperazine (mCPP) 3,4-Methylenedioxy-1-benzylpiperazine (MDBZP) 4-Methoxyphenylpiperazine (MeOPP) Methoxypiperamide (MeOP or MEXP) 4-Chlorophenylpiperazine (pCPP) 4-Fluorophenylpiperazine (pFPP) 3-Trifluoromethylphenylpiperazine (TFMPP) Urologicals Sildenafil Vardenafil Others 6-Nitroquipazine Antrafenine Diethylcarbamazine Diphenazin Fipexide Imatinib NSI-189 Piperazine (itself) Pipobroman (antineoplastic agent) Quipazine Sunifiram (nootropic) Tolpiprazole (tranquilizer) Most of these agents can be classified as either phenylpiperazines, benzylpiperazines, diphenylmethylpiperazines (benzhydrylpiperazines), pyridinylpiperazines, pyrimidinylpiperazines, or tricyclics (with the piperazine ring attached to the heterocyclic moiety via a side chain). See also Pyridine Pyrazine Piperidine Amine gas treating Methyl diethanolamine References External links Piperazines Anthelmintics Diamines