This conveniently prepared reducing agent has been used for delicate reductions in cases where KC8 or alkali metal naphthalenides are too harsh. It is prepared by following the procedure described by Jones et al. which generates a 5% w/w dispersion.[1]
Procedure: NaCl should be pre-dried in an oven at a temperature higher than 100degC at least overnight. The salt’s particle size should be made as fine as possible by means of a blender (Published procedure uses a domestic kitchen blender for 30 min).
A 1-liter Schenk flask equipped with a stir bar was loaded with finely ground, pre-dried NaCl (80g), and placed under high vacuum. The salt was heated at around 200degC for 3h. After allowing the flask to cool to room temperature, it was filled with argon, and metallic sodium (4g, 174mmol) was added. Under vigorous stirring, the contents of the flask were heated to 110degC, melting the sodium in the process. Once the sodium and NaCl became homogenized (approximately 1h), the blueish gray powder was placed under vacuum and brought into the glovebox. The solid was stored in a vial and kept at room-temperature under air/moisture-free conditions.
Notes
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NaCl is hygroscopic, thus the pre-drying step is of paramount importance to ensure removal of adventitious water.
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Blending step is also extremely important, as store-bought NaCl particle sizes are too large. Larger particle sizes lead to poor reducing agent performance.
[1] Hicks, J.; Juckel, M.; Paparo, A.; Dange, D.; Jones, C. Organometallics 2018, 37, 24, 4810-4813.