Aerobic oxidation of organic compounds in the presence of the free base porphyrins and porphyrins supported onto nanostructure solid as photosensitizer

Photosensitizer generation is a simple and controllable method for the production of 1O2 oxygen, requiring light at specific wavelengths, and a photosensitizer capable of absorbing and using that energy to excite oxygen to its singlet state. The types of photosensitizers are: (1) the organic dyes and aromatics; (2) the porphyrins, phthalocyanines, and related macrocycles; (3) semiconductors; and (4) transition metal complexes. The porphyrins and their derivatives have the ability to absorb several wavelengths in the UV-vis range used as photosensitizer in synthetic chemistry and have high photostability compare to other photosensitizers [1].In recent years, immobilized photosensitizers have been used for generation of singlet oxygen [1-2]. In present study, meso-tetrakis(4-hydroxyphenyl)porphyrin (H2THPP) and meso-tetrakis(4-carboxyphenyl)porphyrin (H2TCPP) immobilized on the functionalized multi-walled carbon nanotubes (MWCNTs) were utilized as highly efficient, stable and reusable heterogeneous photocatalysts for the aerobic oxidation of olefins under green conditions. The influence of different parameters including the photosensitizer to olefin molar ratio, solvent, type of light source has been investigated. The use of 1,4-benzoquinone and 1,3-diphenylisobenzofuran as the quencher of superoxide anion radical and singlet oxygen species revealed that oxidation reaction mainly proceeds with a singlet oxygen mechanism