The proton magnetic resonance spectrum of a dilute solution of formamide-15N in CH,CN at 15 "C undergoes definite changes as bromide ion in the form of (C,H,),NBr is added. The two amide resonances shift downfield, but at different rates. It is found that each amide hydrogen forms hydrogen bonds with bromide ions, apparently by way of independent equilibrium processes. The hydrogen bond at the trolls position to the carbonyl oxygen is favored by about 0.7 kcal mole-' over that at the cis position. It is postulated that electrostatic repulsion between any base and the carbonyl oxygen of an arnide group, tends to favor formation of hydrogen bonds at the more remote, trans, hydrogen. This may account for the formation of hydrogen-bonded chains by N-monosubstituted amides preferentially with the amide hydrogen trorzs to oxygen.

The n.m.r. spectrum of ethylene adsorbed on Nay, Cay-72, and Cay-87 is dependent on the coverage. At low coverages of ethylene, specific adsorption at the calcium ions gives rise to a broad resonance. As the coverage increases, non-specific adsorption becomes predominant and the linewidth decreases markedly. At very high coverages ethylene adsorbed on the calcium zeolitcs undergoes catalytic oligomerization and polymerization, as evidenced by the growth of bands due to methyl groups and to polyethylene. Except at very low coverages, very little variation of linewidth is observed on the N a y zeolite (or on NaX).