Lacivita, Enza published the artcileDetermination of 1-aryl-4-propylpiperazine pKa values: The substituent on aryl modulates basicity, Quality Control of 178928-58-0, the publication is Bioorganic & Medicinal Chemistry (2009), 17(3), 1339-1344, database is CAplus and MEDLINE.
In order to design a potential drug, it is important to know its pKa because the protonation state of the mol. will be critical for ligand-receptor interaction and for the pharmacokinetic of the mol. pKa values of a series of 1-(substitutedphenyl)-4-propylpiperazines were measured to study how the presence of a substituent on the Ph ring modulates the basicity of N-4 nitrogen. pKa values indicated that the position of the substituent was crucial. In general, the introduction of the substituent in ortho-position of the Ph ring increased the basicity of the mol. This effect appeared to be related to steric and conformational effects and not to the electronic properties of the substituent. On the other hand, meta- and para-substituted derivatives showed a slight decrease of pKa that was qual. consistent with the electronic properties of the substituent.
Bioorganic & Medicinal Chemistry published new progress about 178928-58-0. 178928-58-0 belongs to piperazines, auxiliary class Piperazine,Nitrile,Benzene, name is 1-(3-Cyanophenyl)piperazine, and the molecular formula is C11H13N3, Quality Control of 178928-58-0.
Referemce:
https://en.wikipedia.org/wiki/Piperazine,
Piperazines – an overview | ScienceDirect Topics