1-(2-Naphthyl)piperazine
1-piperazine, also known as 1-deazaquipazine, is a serotonin receptor modulator and putative serotonergic psychedelic of the arylpiperazine family related to quipazine.
It shows affinity for the serotonin 5-HT1, 5-HT2, and 5-HT3 receptors and is known to act as a serotonin 5-HT2A receptor partial agonist. Conversely, it has negligible affinity for the serotonin 5-HT1D receptor. The drug produces the head-twitch response, a behavioral proxy of psychedelic effects, in rodents, although it was less efficacious than quipazine. This effect was absent in serotonin 5-HT2A receptor knockout mice. In addition, 2-NP fully generalizes to the psychedelic DOM in animal drug discrimination tests. Hence, it may have hallucinogenic effects in humans.
Along with quipazine, the drug is one of a relatively small number of known psychedelics that is distinct from the tryptamine, phenethylamine, and lysergamide families. It was first described in the scientific literature by at least 1961.