text: 2,2,6,6-Tetramethylpiperidine, abbreviated TMP, HTMP, or TMPH, is an organic compound of the amine class. In appearance, it is a colorless liquid and has a "fishy", amine-like odor. This amine is used in chemistry as a hindered base (hindered amine).  Although TMP finds limited use per se, its derivatives are a mainstay of hindered amine light stabilizers.
  TMP is the starting material for an even stronger base, lithium tetramethylpiperidide and the radical species TEMPO. Another non-nucleophilic base is N,N-diisopropylethylamine.  Its aqueous pK (conjugate acid dissociation constant, a measure of basicity) is 11.07 at 25 °C, while its pK (acid dissociation constant, a measure of acidity) is approximately 37.