pempidine pempidine pempidine is a ganglion-blocking drug, first reported in 1958 by two research groups working independently, and introduced as an oral treatment for hypertension. pempidineidentifiers iupac name 1,2,2,6,6-pentamethylpiperidine cas number79-55-0pubchem cid6603chemspider6353uniin5i18ji9d6chemblchembl1617409comptox dashboard (epa)dtxsid7046962 echa infocard100.001.102 chemical and physical dataformulac10h21nmolar mass155.285 g·mol−13d model (jsmol)interactive image smiles cc1(cccc(n1c)(c)c)c pharmacology reports on the "classical" pharmacology of pempidine have been published. the spinks group, at ici, compared pempidine, its n-ethyl analogue, and mecamylamine in considerable detail, with additional data related to several structurally simpler compounds. toxicology ld50 for the hcl salt of pempidine in mice: 74 mg/kg (i.v.); 125 mg/kg (i.p.); 413 mg/kg (p.o.). chemistry pempidine is an aliphatic, sterically hindered, cyclic, tertiary amine, which is a weak base: in its protonated form it has a pka of 11.25. pempidine is a liquid with a boiling point of 187–188 °c and a density of 0.858 g/cm3. two early syntheses of this compound are those of leonard and hauck, and hall. these are very similar in principle: leonard and hauck reacted phorone with ammonia, to produce 2,2,6,6-tetramethyl-4-piperidone, which was then reduced by means of the wolff–kishner reduction to 2,2,6,6-tetramethylpiperidine; this secondary amine was then n-methylated using methyl iodide and potassium carbonate. hall's method involved reacting acetone with ammonia in the presence of calcium chloride to give 2,2,6,6-tetramethyl-4-piperidone, which was then reduced under wolff-kishner conditions, followed by n-methylation of the resulting 2,2,6,6-tetramethylpiperidine with methyl p-toluenesulfonate.