Then the catalyst is neutralized and salts and impurities removed in a series of filtrations and washes. The molten DLTDP and DSTDP are converted to solid products by flaking and packaged. The liquid DTTDP product is drummed. The TDPN intermediate is made by reacting acrylonitrile and sodium sulfhydrate in aqueous solution.
thiodipropionitrile (TDPN), with different fatty alcohols. DLTDP uses lauryl alcohol, DTTDP uses iso-tridecyl alcohol and DSTDP uses stearyl alcohol. The reaction of TDPN with the alcohols is an esterification using acid catalysts (hydrochloric acid and sulfuric acid). Water is removed under vacuum to drive the esterification to completion.
Synergistic effect is expected when primary antioxidants are used together with secondary antioxidants as primary antioxidants are not very effective against the degradation by UV oxidation. Sometimes, chelating agents are added to scavenge metal impurities which can initiate decomposition.
Examples of peroxide decomposer type of antioxidant are trivalent phosphorous and divalent sulfurcontaining compound such as sulfides, thiodipropionates and organophosphites.
The function of antioxidants is to inhibit the formation of the radical species. Hindered phenolic antioxidants are usually considered as chain terminators.