Nitroso-4-piperidinol , its CAS NO. is 55556-93-9, the synonyms are 5-21-01-00076 (Beilstein Handbook Reference) ; BRN 1447942 ; N-Nitroso-4-hydroxypiperidine ; Nitrosopiperidinol ; 4-Piperidinol, N-nitroso- .