Infrared assisted interaction between a monolayer of octadecylamine and 2 hydroxy 5 nitro benzaldehyde in solution has been carried out at air/solution interface. The amphiphilic Schiff base resulting from the reaction seems to generate a slow surface pressure perturbation in the monolayer without disturbing the bulk phase. π-A (Surface pressure-molecular area) isotherms and absorption spectroscopy have been used to characterize the Schiff base formed at the air/water interface. Enhanced light reflection spectra on the air/solution interface also confirm the formation of the compound. Brewster angle microscpy (BAM) indicates clustering of the product in the presence of the IR which then separate on switching off the source. The change in surface area at constant pressure with time seems to indicate a thermomechanical effect possibly due to an on/off contact between the amphiphilic Schiff base as it is formed and the rate of formation slows down as the reaction reaches an equilibrium.