INFLUENCE OF ALKYL CHAIN-LENGTH UPON THE SOLID-STATE PHOTOREACTIVITY OF P-PHENELENDIACRYLIC ACID MONOESTERS

The photoreactivity of a series of crystalline p-phenelendiacrylic aci d monoesters has been investigated. The ethyl derivative forms photost able crystals whereas cycloaddition reactions yield a mixture of a p-c yclophane and oligomeric products from n-decyl crystals. Crystal struc ture analysis for both compounds shows that the packing is driven by t he steric disparity between the alkyl chains and the p-phenelendiacryl ic acid. However only the more planar n-decyl molecules are correctly aligned for the photocycloaddition reaction.