Photochemistry and photophysics of 1-naphthyl acylates in polyethylene films.

摘要

This thesis describes the use of polyethylenes as reaction media for conducting the photo-Fries rearrangements of 1-naphthyl acylates. The photo-Fries rearrangements of three 1-naphthyl acylates have been investigated in three unstretched and stretched polyethylene films and in isotropic solutions. The influence of variables such as the size and position of the acyl groups on the naphthyl rings, the degree of film crystallinity, film free volume, and the unstretched/stretched state of the films on the rearrangements has been explored. The crystal structure of 2-naphthyl acetate was determined and compared with that of 1-naphthyl acetate. Their electric dipole moments were evaluated by both theoretical and experimental methods, and were applied to interpret their polarized spectroscopies. The polarized spectroscopy of both 1- and 2-naphthyl acylates in unstretched/stretched polyethylene films supports the idea that stretching reduces free volume and increases the order of guest molecules. The degree of order increases with the length of acyl groups for 1-naphthyl acylates, but 2-naphthyl myristate is less ordered than the 1-naphthyl acylates.; Higher viscosity or lower temperature “hardens” reaction cavity walls and confines more the movement of guest species, thus enhancing the selectivity of photo-Fries rearrangements of 1-naphthyl acylates.; The selectivity of the photo-Fries rearrangements of 1-naphthyl acylates is larger in PE films than in isotropic solutions, and increased with the size of the aryl group, crystallinity of film, and upon film stretching. Long alkyl chains on naphthyl myristates not only affect the shape anisotropy of their cavities but also induce large van der Waals interactions with the cavity walls. Film stretching enforces the templating effect of the cavities and strengthens the van der Waals attractions between the guest molecules and polymer chains that constitute the cavity walls in the case of naphthyl myristates.