Alkaline Medium, The Aryl Ether Bond Stability Study

Substituted aryl ethers are the key intermediate compounds to synthesize dye, medicine, pesticide and so on. It is of very importance to study their stability for synthesizing these compounds. A series ramification of aryl ethers that containing strong electrowithdrawing group (-NO2) have been synthesized, which were used as the studied substrate and the stability of aryl etherbond in the alkaline medium has been researched.The project is divided into two parts: Firstly, four kinds of aryl ethers have been synthesized, which are p-nitro aryl ethers, o-nitro aryl ethers, phenyl ethers, p- methyl aryl ethers. The content of these objective products has been determined by high performance liquid chromatography, the melting point has been measured by capillary tube method, their structures have been confirmed by 'H-NMR spectra. Secondly, these compounds were used as substrate to take place chemical reactions under basic condition. P-nitro methylbenzene has been taken as the internal standard. Extent of etherbond cleavage has been analyzed quantitatively by high performance liquid chromatographic instrument. Degree of conversion of aryl ethers has been determined.The results of the experiments show that substituted aryl ethers that containing nitro group (-NO2) are easy to take place nucleophilic substitution in the alkaline medium and then aryl etherbond is cleaved. Extent of etherbond cleavage becomes more and more intensive with higher alkaline concentration, higher reaction temperature, longer reaction time, stronger activity of nucleophilic reagent, and these substituted aryl ethers will become more and more unstable. The abnormal behaviour which happened in the nucleophilic substitution process of phenoxy propionic acid has been discovered. The mechanism has been proposed as an intramolecular nucleophilic substitution by neighboring group participation.