Free Catalyzed Synthesis of 2,2′-Bipyridine via Ozonolysis Technique

Abstract

ABSTRACTThe ozonation of a triple bond in organic compounds is rare in industry. The reaction is much more complicated to run, because ozone is an electrophilic agent and more likely to bind to the double bond compared to the triple bond in an organic compound. This may be a problem because some fine organic substances are very hard to synthesize and can only be solved by the ozonolysis technique of a triple-bond organic compound. In addition, oxidation by using ozone is also preferred because of the cleanliness and effectiveness of the reaction. A novel method for the synthesis of 2,2ʹ-bipyridine was described, which involves ozonolysis of a 2-ethynylpyridine and is supported by a high-pressure reactor. The reaction proceeds via ozone attack on the acetylenic triple bond, cleavage, and free radical formation. The present study establishes the conditions for selective ozonolysis of 2-ethynylpyridine, leading to 2,2ʹ-bipyridine. The 2,2ʹ-bipyridine was characterized by gas chromatography flame ionization detector (GC-FID) and mass spectroscopy techniques. A novel suggested mechanism was used to explain the oxidation process. Analysis showed that the formation of oxidized product is shown when ozone is supplied in excess, which shows that the reaction between 2-ethynylpyridine and ozone is a first-order reaction, whe reby the result of the relationship only depends on the concentration of the starting material, which is 2-ethynylpyridine acts as the limiting reactant.