Carbamide peroxide is prepared by crystallizing urea with hydrogen peroxide to form a solid adduct. Starting with 66 g urea and 150 g of 25–30% hydrogen peroxide in 250 mL, the mixture is stirred, heated to dissolve urea (microwave ~1 minute at medium power to ~75–80°C), then cooled in a freezer to around 0–5°C to crystallize. Crystallization continues for about an hour, and the crystals are filtered and dried without washing. First batch yields about 46 g of product; a MnO₂ test confirms the crystals act as carbamide peroxide. The filtrate is chilled again to obtain a second batch, and the combined product is 80 g, about 77% yield from the starting reagents. Carbamide peroxide provides the oxidizing power of concentrated hydrogen peroxide with safer handling and is used in DIY tooth bleaching; plans for further use are mentioned.
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