Crystalline solid, functional groups bound

The reaction of NO with the double bonds of enamines also produces compounds containing the diazeniumdiolate functional group bound to carbon, and some of the compounds prepared in this way have the potential to serve as spontaneous NO donors [43]. The compounds chosen for study were enamines 1-4 derived from condensation of cyclopentanone or cyclohexanone with morpholine or pyrrolidine. When these enamines were dissolved in acetonitrile and treated with NO gas (5-atm pressure) at room temperature, a vigorous exothermic reaction resulted, accompanied by high uptake of NO and formation of a brown precipitate. Attempts to isolate the solid precipitates often resulted in rapid decomposition, with the release of large volumes of gaseous NO. At -78 °C in diethyl ether, the reaction of 4-(l-cyclohexen-l-yl) morpholine (IX) afforded a good yield of crystalline NO addition product (X) ... 

Organic functional groups covalently bound to the surface of crystalline solids or insoluble polymers are subject to special constraints which may alter their reactivity in comparison with analogous small molecules. 

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