Tetrapropylammonium (TPA) is a quaternary ammonium cation with the formula [N(C3H7)4]+, also denoted [NPr4]+ (where Pr = propyl group).

TPA is chemically similar to other quaternary ammonium cations with saturated alkyl groups.

Like other quaternary ammonium cations, TPA is prepared by the alkylation of the corresponding ammonia analogue, tripropylamine.

[5] The TPA salt tetrapropylammonium perruthenate (TPAP) is an effective and highly selective oxidiser, with numerous applications in organic synthesis.

[6][7] Combined with a cooxidant, it serves as a catalyst for the oxidation of primary and secondary alcohols to aldehydes and ketones.