Preparation of Commercial Epoxy Resins

The earliest developed commercial epoxy resins were diglycidyl ethers of 4,4 -isopropylidine-diphenol (Bisphenol A) formed by reacting epichlorohydrin with the diphenol. The reaction sequences involve formations of alkoxide ions, followed by nucleophilic additions to the least hindered carbons 

This is followed by ring closures through internal displacement of chloride ions  

As explained in the discussion on phenoxy resins, a reaction of two moles of epichlorohydrin with one mole of the diphenol yields higher molecular weight byproducts and only 10% of the diether  

To obtain high yields of the diether, the quantities of epichlorohydrin in the reaction mixtures must be doubled or tripled. This can result in yields as hi as 70%. Another advantage of a laige 

A different route to the diglycidyl ethers is via Friedel-Craft reactions  

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