Transfers of this type were done after venting the low-boiling gases from the trap since the NMR measurements were obtained at temperatures at or above ambient. In no case was air permitted to come into contact with the sample. Materials Highest-purity methane was obtained from Matheson, Inc. Concentrated ammonium hydroxide was of analytical reagent grade purity. Reference substances were obtained from Aldrich Chemical Company. Unassigned resonances were compared with known substances by direct additions of the latter to the reaction mixtures.
All shifts are relative to external tetramethylsilane.
Infrared Spectra Spectra were obtained from samples dried over P 2 O 5 and prepared as pressed KBr pellets. Infrared absorption recordings were obtained on a Beckman Acculab-10 spectrophotometer. The cuvettes were then transferred to water baths at different temperatures, and the absorbance change at 600 nm during a 15-min time interval was recorded. The small size of the NMR cuvette permitted rapid thermal equilibration. Home A disadvantage of the experimental arrangement shown in Figure 1 is its tendency to cause a change in the composition of the reacting gas mixture, e.g., NH 3 will be depleted as the reaction progresses.