The homogeneous reaction CD 4 + NH 3 → CD 3 H + NH 2 D: The effect of ethane impurities

The homogeneous exchange reaction between tetradeutero methane and ammonia was studied behind reflected shocks in a single‐pulse shock tube over the temperature range of 1300–1800°K. The rate of production of CD 3 H at the early stages of the reaction in mixtures ranging between 1‐4.5% NH 3 and 1–4.3% CD 4 in argon is given by d [CD 3 H]/ dt = k b [CD 4 ] 0 [NH 3 ] 0 , where k b =8 × 10 16 exp (−65.3 × 10 3 / RT ) cm 3 /mole·sec. This activation energy is considerably lower than the one that may be expected on the basis of a pure free radical mechanism. It is rationalized by C 2 D 6 impurities in the methane. No clear answer can be obtained regarding the role of a four‐center intermediate in this reaction.