Methylacetylene and tert-butylacetylene as IR-probe molecules for the characterisation of basicity

Abstract

Methylacetylene (MA) and tert-butylacetylene (TA) were used as probe molecules in infra-red spectroscopy for characterisation of the basicity of MgO. Reference experiments with SiO 2 showed the formation of a π-complex via the CC bond of MA or TA with the weakly acidic silanol groups. The adsorption model proposed for MA and TA on MgO involves a H-bonding adsorption interaction of the probe molecule via the acidic CH end with the basic O 2− sites with a possible simultaneous interaction of the CC bond with OH groups which are preferentially located at corners on the MgO surface.