H–D Exchange between methane and deuteriated potassium amide supported on alumina

The H–D exchange reaction between methane and deuteriated potassium amide supported on alumina (KND2/Al2O3), a strongly basic catalyst, has been investigated by FTIR spectroscopy. KND2/Al2O3 was prepared by contacting KNH2/Al2O3 with D2 at 373 K for 30 min. The N–D asymmetric and symmetric bands in KND2 were observed at 2411 and 2343 cm−1. The ND2 bending bands were observed at 1132 cm−1. The H–D exchange reaction between CH4 and KND2 proceeded at room temperature. First, the N–H bands in KNDH were observed at 3210 cm−1. and then KNDH was further converted to KNH2, whose N–H stretching bands were observed at 3238 and 3190 cm−1. The H–D exchange reaction between ethane and KND2/Al2O3 also proceeded at room temperature, but the rate was slower than that between methane and KND2/Al2O3. The lower reactivity of ethane indicates a carbanion mechanism since the acidity (pKa) of ethane (42) is lower than that of methane (40).