Optimization of the Synthesis of A.O.2246 Antioxidant and its Phenolic Intermediate

Use of antioxidants in the formulation composite propellants is unavoidable. These materials are added to the propellants to given them stability during storage time. In this paper, different methods of synthesis of A.O.2246 and its phenolic intermediate were investigated and then considering the advantages and disadvantages of these methods and their potential in scaling up, the preferred method for preparation of these materials was adopted. The commonly used procedure for the production of the intermediate 2-t-butyl-4-methylphenol (by reaction of p-cresol with t-butyl alcohol in the presence of phosphoric acid) produces by-products whose separation from the desired material needs consecutive basic and acidic extractions followed by recrystalization. In this work, by optimizing the reaction conditions, we have synthesized the intermediate in 99% purity and 95% yield without any need to go through the separation process. Then by reaction of the produced intermediate with formaldehyde in the presence of concentrated sulfuric acid and sodium dodecyl sulfate, A.O.2246 was produced. High yield of the reaction product, mild reaction condition, short reaction time and its potential to scaling up are the advantages of this method.