1,4-Piperazinebis(ethanesulfonic acid) 1,4-Piperazinediethanesulfonic acid 10010-67-0 2,2'-(Piperazine-1,4-diyl)bis(ethanesulphonic) acid 5625-37-6 EINECS 227-057-6 NSC 157117 PIPES Piperazine-N,N'-bis(2-ethanesulfonic acid)