PHOTOCHEMICAL and PHOTOPHYSICAL PROPERTIES OF PIROXICAM and BENOXAPROFEN IN VARIOUS SOLVENTS

Abstract
Laser flash spectroscopy was used to examine the title compounds. Piroxicam has a triplet transient with a maximum near 450 and a lifetime of 3-21 .mu.s depending on the solvent. The relative quantum yield is highly solvent dependent being maximum in toluene and .gtoreq.14 fold lower in hydrogen bonding solvents. There is another transient which is assigned as a proton transferred ground state transient. Some permanent photoproduct also appears to be produced. Benoxaprofen also has a triplet transient with a maximum near 420 nm with a lifetime of 65 .mu.s to .gtoreq.250 .mu.s depending on the solvent. In this cases, the relative quantum yield only slightly varies among polar and hydrogen bonding solvents. This is in marked contrast to published data on the fluorescence yield. Some permanent photoproduct appears to be produced.