Preparation of Diaryliodonium Salts with Hydroxy and Carboxylic Acid Groups (2021-04-09)

Abstract

Toxic transition metals are often used in organic synthesis reactions, which poses apotential hazard in their applications, especially medicinally and environmentally. Apotential solution to this problem is to use trivalent iodine in place of toxic transition metalsin synthesis. One class of compounds that could be specifically useful in toxic transitionmetal replacement is pseudo-cyclic iodonium triflate salts. This project focuses onproducing the best method and scope for the preparation of diaryliodonium salts fromiodosobenzoic acid-triflate (IBA-OTf) and (3-acetoxyphenyl)-3-iodanediyl diacetatecompounds. These compounds could be used in oxidation reactions, replacing commonlyused transition metals and would be safer and more environmentally friendly reagents. Thepreparing of these diaryliodonium salts can be optimized since there are various possiblesynthesis conditions available. It was important to find optimal methods for preparingdiaryliodonium salts avoiding the use of toxic transition metals. First, benzene was investigated to test which starting material was best suited for thesynthesis of diaryliodonium salts. Then several other precursors were tested in the reactionto see if it could form trivalent iodine, especially compounds less carcinogenic thanbenzene. After working with other compounds, optimization of the most suitable reactionwas conducted. Dichloromethane and acetonitrile were found to be the most suitable solvents for thesynthesis of diaryliodonium salts from the starting materials mentioned. It was also foundthat triflic acid (TfOH) was necessary for cleaving or breaking bonds in the synthesis ofdiaryliodonium salts. The products were found to be completely soluble in acetonitrile,which was useful for transferring in the reaction. There were several compounds that wereable to react to form diaryliodonium salts with high yield. In conclusion, the hypothesis wassupported with the successful optimization of diaryliodonium salts syntheses from IBA-OTfand (3-acetoxyphenyl)-?3-iodanediyl diacetate compounds.