| 摘要 |
<p>A method of preparing hindered phenolic antioxidants for lubrication oils or other organic media having reduced residual tin or titanium levels is disclosed herein. A low amount of a tin or titanium catalyst is used resulting in low residual metal levels. The method provides for deactivation of the metal transesterification catalyst with an oxidizing agent, a reducing agent or clay treatment. Treatment with clay, preferably acid treated clay, and more preferably acid treated bentonite clay, after deactivation with the oxidizing agent or reducing agent can further reduce residual tin levels to less than 10 ppm. By deactivating the metal catalyst prior to isolating the antioxidant from the reaction mixture, further reaction at the terminal diol of the reaction product is prevented. The final product mixture may be used without further purification and has improved solubility in lubrication oils and other organic media.</p> |
