Boron is extracted based on the reaction between boric acid and glycol, while the boric acid ester is hydrolyzed during the back-extraction at the action of alkali or acid.
[H.sub.3]B[O.sub.3] can also be expressed as B[(OH).sub.3], and the esterification reaction between alcoholic hydroxyl and -OH in B[(OH).sub.3] will generate a stable six-membered ring structure of boric acid ester after producing two molecules of water; thus, the accurate reaction of R3 is expressed in the following reaction:
The zinc oxide layer was considerably reduced in the presence of cobalt naphthenate and boric acid ester in compounds which provided the highest aged adhesion.
Elschner, "The influence of boric acid ester on the structure and composition of the rubberbrass interface," paper presented at Rubber Division Meeting, Louisville, 1992.