H-D EXCHANGE BETWEEN METHANE AND DEUTERIATED POTASSIUM-AMIDE SUPPORTED ON ALUMINA

The H-D exchange reaction between methane and deuteriated potassium am ide supported on alumina (KND2/Al2O3), a strongly basic catalyst, has been investigated by FTIR spectroscopy. KND2/Al2O3 was prepared by con tacting KNH2/Al2O3 with D-2 at 373 K for 30 min. The N-D asymmetric an d symmetric bands in KND2 were observed at 2411 and 2343 cm(-1). The N D2 bending bands were observed at 1132 cm(-1). The H-D exchange reacti on 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 an d 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 indica tes a carbanion mechanism since the acidity (pK(a)) of ethane (42) is lower than that of methane (40).