Production and applications of diisopropyl peroxide

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Dicumyl peroxide is also known as curing agent DCP or dicycumyl peroxide. Molecular formula: C18H22O2, relative molecular mass: 270.37. The structural formula is: http://www.zshg.com/wenzhang/chanpingongyi/e5/gyh5-1.gif. Physical and chemical properties: white crystals. Melting point 41–42°C. Relative density 1.082. The decomposition temperature is 120–125°C. Stable at room temperature; gradually turns slightly yellow when exposed to light. Insoluble in water, soluble in ethanol, ether, acetic acid, benzene, and petroleum ether. The active oxygen content is 5.92% (purity 100%) and 5.62% (purity 95%). Half-life in benzene: 171°C: 1 min ； 117℃:10h ； 101℃:100h. It is a strong oxidizing agent. Primary uses: It is mainly used as a vulcanizing agent for natural rubber and synthetic rubber, as an initiator for polymerization reactions, and can also be used as a cross-linking agent for polyethylene resin. Cross-linked polyethylene is used as a cable insulation material; it not only possesses excellent insulating and processing properties but also improves heat resistance. For 100 parts of polyethylene, 2.4 parts of the vulcanizing agent DCP are used. The vulcanizing agent DCP enables ethylene-vinyl acetate copolymer (EVA) foam materials to develop fine and uniform cells, while improving the heat resistance and weather resistance of the products. It is also used as a curing and crosslinking agent for unsaturated resins and polyesters. Laboratory preparation: In a 500 mL three-necked reaction flask, 121.6 g of isopropylbenzene peroxide, 108.8 g of http://www.zshg.com/wenzhang/chanpingongyi/e5/a.gif-phenylisopropanol, and 36 g of anhydrous oxalic acid were added. The mixture was kept in a water bath at 40°C with stirring for 8 hours; after cooling, oxalic acid was filtered out. 200 mL of benzene was added to the filtrate. The benzene layer was separated, washed separately with 4 mol/L NaOH solution and water, and then subjected to vacuum distillation at a temperature of 95°C. Distillation was carried out first at a pressure of 15×133.3 Pa, after which the pressure was reduced to (1–2)×133.3 Pa for further distillation at the same temperature, yielding 196 g of crude product. Diisopropyl peroxide with a melting point of 40–41°C is obtained by recrystallization from methanol. Production principle: The reducing agent sodium sulfite is used to reduce cumene hydroperoxide to phenyldimethylmethanol, which then condenses with cumene hydroperoxide in the presence of perchloric acid; subsequent processing yields diisopropyl peroxide. http://www.zshg.com/wenzhang/chanpingongyi/e5/gyh5-2.gif Process flow; http://www.zshg.com/wenzhang/chanpingongyi/e5/gyh5-3.gif Raw material ratios (kg/t): Isopropylbenzene peroxide (32%～35%) – 1500, Liquid caustic (30%) – 70, Sodium sulfite (96%) – 980, Perchloric acid (72%) – 2. Main equipment: Reduction reactor, Condensation reactor, Concentration tank, Filter, Vacuum dryer, Storage tanks. Production process: An aqueous solution composed of 78 parts of isopropylbenzene peroxide (≥32%) and 98 parts of sodium sulfite is poured into the reduction reactor, where heterogeneous reduction takes place at 62–65°C to yield phenyldimethylmethanol. The resulting phenyldimethylcarbinol was condensed with 72 parts of isopropylbenzene peroxide in the presence of 0.2 parts of perchloric acid at 42–45°C, yielding a cumene peroxide condensation mixture. After washing with 10% sodium hydroxide solution until neutrality, the water is removed, and the mixture is concentrated by vacuum distillation. It is then dissolved in anhydrous ethanol, cooled below 0°C to induce crystallization; after filtration, it is dried under vacuum to yield the final product, diisopropyl peroxide. Ethanol is recovered from the filtrate. Quality indicators: http://www.zshg.com/wenzhang/chanpingongyi/e5/gyh5-4.gif Quality inspection: (1) Purity determination: Accurately weigh about 0.2 g of the solid sample, place it in a clean and dry 100–150 mL iodine flask, add 1.0 g of sodium bicarbonate, 2.0 g of solid potassium iodide, and 10 mL of glacial acetic acid, then shake well. Clamp the iodine bottle with a condenser tube, place it in a water bath at 65°C, and slowly add 3.0 mL of hydrochloric acid while shaking gently; continue adding the acid until only a few bubbles appear in the solution. Then cover the bottle loosely with its stopper and let it stand for 15–20 minutes. After that, add 50 mL of distilled water, and immediately titrate with a 0.1 mol/L sodium thiosulfate solution until a pale yellow color is reached. Add 10 drops of starch indicator and continue titrating until the blue color disappears, at which point the titration is complete. Follow the same procedure but use no hydrochloric acid as a blank test. http://www.zshg.com/wenzhang/chanpingongyi/e5/gyh5-5.gif (2) Determination of melting point: It is carried out in accordance with GB 617-88 \"General method for determining melting point range\". (3) Determination of total volatiles: Take about 10 g of a homogeneous sample, place it in a weighing flask that has been pre-weighed to constant weight, weigh it accurately, and dry it under vacuum at room temperature until a constant weight is reached (weighing once every 2 hours). The total volatile matter content X (%) is calculated using the following formula: http://www.zshg.com/wenzhang/chanpingongyi/e5/gyh5-6a.gif http://www.zshg.com/wenzhang/chanpingongyi/e5/gyh5-6a.gif Safety measures: (1) The raw material, isopropylbenzene peroxide, is a strong oxidizing agent. The product is a first-class organic oxide that can explode when exposed to light or heat. (2) Packaged in iron drums lined with polyethylene plastic bags, and marked with hazard symbols. Store in the dark at temperatures below 30°C.