1-Butyl-2-pyrrolidinone 1-Butylpyrrolidin-2-one 2-PYRROLIDINONE, 1-BUTYL- 3470-98-2 5-21-06-00329 (Beilstein Handbook Reference) BRN 0111543 EINECS 222-437-8 N-Butylpyrrolidinone N-Butylpyrrolidone