text: Pempidine is an aliphatic, sterically hindered, cyclic, tertiary amine, which is a weak base: in its protonated form it has a pK of 11.25.
  Pempidine is a liquid with a boiling point of 187–188 °C and a density of 0.858 g/cm.
  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.
  Halls 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.