A Stable and Safe Form of Iodine Azide: Polymer-Bound Bisazidoiodate(I)

References and Notes
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11 Preparation of Polymer-Bound Bisazidoiodate(I) 3Amberlyst^® A26 resin (4.2 mmol/g hydroxide form) was sequentially rinsed with 1 M NaOH (4 mL g^–1 polymer), saturated LiI solution (5 mL g^–1 polymer), distilled water (4 mL g^–1 polymer), isopropanol (4 mL g^–1 polymer), and CH₂Cl₂ (4 mL g^–1 polymer). A suspension of this polymer and PhI(OAc)₂ (1.8 equiv) was shaken in dry CH₂Cl₂ (3 mL g^–1 resin) at 665 rpm for 6 h at room temperature under an argon atmosphere. During this time, the reaction mixture was protected from light. The pale-yellow resin 2 was filtered, washed with CH₂Cl₂ (30 mL g^–1 resin), and dried in vacuo. The polymer can be stored for several months under argon atmosphere at –15 °C in the dark without loss of activity. Subsequently, a suspension of this functionalized ion-exchange resin 2 (4.2 mmol anion g^–1 resin, 1.0 equiv) and trimethylsilyl azide (2.6 equiv) in dry CH₂Cl₂ (4 mL/g resin) was shaken at 665 rpm for 6 h at room temperature in the absence of light under an argon atmosphere. The orange resin 3 was filtered, washed with CH₂Cl₂ (30 mL g^–1 resin), and dried in vacuo. In practice, an effective loading of up to 2.1 mmol of reagent g^–1 of resin can be achieved. It can be stored for several months under argon atmosphere at –15 °C in the dark without loss of activity.
12 It is worth noting that polymer 3, after being evaluated as safety, was commercially available for several years in the early 2000s.
13 Note: The number of equivalents for 3 refers to the theoretical loading as specified by the manufacturer of the ion-exchange-resin. The actual amount of IN₃ available is much less, therefore the number of equivalents does not describe the true ratio.