2,4,6-collidine 15.0g (0.1238 mol) was added dropwise into 20% oleum 70mL in a 0.5L flask on ambient oil bath. (Quite exothermic). The mixture was brought up to 100 C and powdered potassium nitrate 30g was slowly added in small portions over 15 minutes (nitrous gas evolution). The mixture was stirred under a reflux condenser at 100 C for 5 hous, then cooled and poured on ice (400g). The mixture was made alkaline by adding concentrated aq. ammonia (300mL), cooled and extracted with dichloromethane (3x100mL). The combined extracts were dried (MgSO4) and evaporated. The residue (18g) was re-crystallized from pentane (60mL) at -20C (freezer 14 hours) to obtain 15.75g of pure nitrocollidine. A second crop (1.40g) was obtained by concentrating and cooling the supernatants. Y=17.15g (83.5%) of the nitrocollidine as a light-yellow crystalline solid.
The nitrocollidine 8.00g was hydrogenated in anhydrous ethanol 120mL over 10% Pd-C (3.6g) at 50psi in a Parr shaker for one day. (The hydrogen consumption ceased within 1 hour). The mixture was filtered through a pad of celite, filtrates evaporated and dried on highvac. The solid residue was dissolved in refluxing hexane, filtered while hot, diluted with additional hexane (50mL) and the allowed to crystallize in freezer at -20C overnight (16h). The supernatants were decanted off and the obtained pure aminocollidine was dried on highvac. Y=6.029g (92%) of a white shiny hygroscopic crystalline solid. 1H-NMR(CD3CN, 400MHz): 6.715(s,1H), 3.784(br s, 2H), 3.377(s, 3H), 2.265(s, 3H), 2.081(s, 3H)