4-(2-Hydroxyethyl)-1-piperazine ethanesulfonic acid
2-[4-(2-hydroxyethyl)piperazin-1-yl]ethanesulfonic acid is a HEPES that is ethanesulfonic acid in which one of the methyl hydrogens is replaced by a 4-(2-hydroxyethyl)piperazin-1-yl group. A Good's buffer substance, pKa = 7.55 at 20 ℃. It is a HEPES and an organosulfonic acid. It is a conjugate acid of a 2-[4-(2-hydroxyethyl)piperazin-1-yl]ethanesulfonate. It is a tautomer of a 2-[4-(2-hydroxyethyl)piperazin-4-ium-1-yl]ethanesulfonate.