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<sub>aH</sub> (conjugate acid dissociation constant, a measure of basicity) is 11.07 at 25 ðC, while its pK<sub>a</sub> (acid dissociation constant, a measure of acidity) is approximately 37.
Many routes for the synthesis of TMP have been reported. One method starts with a conjugate addition reaction of ammonia to phorone. The intermediate triacetone amine is then reduced in a Wolff-Kishner reaction.