Redox recipes. VIII. A recipe with ferric versenate, sodium sulfide and hydroperoxide as activating system (veroxasulfide recipe)

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AbstractA new recipe called the Veroxasulfide Recipe is described for the polymerization of butadiene (75)‐styrene (25). The initiating system is composed of ferric versenate, sodium sulfide, and a hydroperoxide. With K‐fatty acid soap as emulsifier, the use of 0.00728 part of ferric nitrate nonahydrate (corresponding to 10−4 M ferric iron in the aqueous phase), 10−4 M versene, 0.02 part of sodium sulfide, and 0.1 part of Diox D, the following conversions are found at 5°C.: Time, hrs. 1 2 4 8 12 Conversion, % 8 16 32 66 85 The optimum amount of sodium sulfide is 0.02 part (equivalent to 0.062 part of the nonahydrate) but the rate does not depend critically on the amount. The optimum rate is found with approximately 0.00025 M ferric versenate (8.3% in 8 hours at 5°C.) and the rate may be adjusted conveniently by adjustment of the amount of ferric versenate. The presence of a considerable excess of versene over ferric iron does not affect the rate. With less versene than the amount equimolar to the amount of ferric iron the rate corresponds approximately to that observed with the corresponding amount of ferric versenate; that is, the rate is determined by the amount of ferric versenate rather than by the total amount of ferric iron. Latex of normal fluidity is obtained with charges containing 0.5 part or more of potassium chloride; without added electrolyte thick latex subject to precoagulation is obtained. Satisfactory rates are found with mixtures of Dresinate 214 and K‐fatty acid soap. Mercaptan is not needed for initiation; the same rate is found with n‐dodecyl mercaptan, with sulfole mercaptan, and without mercaptan. The kind of agitation has no or slight effect on the rate. Added oxygen has only a slight effect which is largely eliminated by the addition of sodium dithionite. A recipe is given which at −5°C. yields 70–75% conversion in 12 hours. Polymerization using the Veroxasulfide recipe at 25°C. may provide a sensitive test for traces of iron in ingredients used in polymerization recipes, since with 2 × 10−6 M ferric versenate (corresponding to 0.1 p.p.m. of ferric iron per liter of aqueous phase), 32% conversion is reached in 11 hours, whereas in the absence of iron 3% conversion is reached in the same time.