N 1777 (OTTO) 4-(4-Nitrobenzyl)pyridine, GR 98%+ Cas 1083-48-3 - used in tests for alkylating agents and in a spectroscopic method for phosgene determination. N 1777 (OTTO) 4-(4-Nitrobenzyl)pyridine, GR 98%+ Cas 1083-48-3 - used in tests for alkylating agents.