Solid sodium hypochlorite
Anhydrous sodium hypochlorite is soluble in methanol, and solutions are stable. I'm not sure about this statement due to methyl hypochlorite. How is
this possible to be stable without that reaction.
Anhydrous sodium hypochlorite can be prepared but, like many hypochlorites, it is highly unstable and decomposes explosively on heating or friction
Sodium hypochlorite can also be obtained as a crystalline pentahydrate
which is not explosive and is much more stable than the anhydrous compound.
Prevention of decomposition
The decomposition is accelerated by carbon dioxide at atmospheric levels.It is a white solid with the orthorhombic crystal structure.
A 1966 US patent claims that stable solid sodium hypochlorite dihydrate can be obtained by carefully excluding chloride ions which are present in the
output of common manufacturing processes and are said to catalyze the decomposition of hypochlorite into chlorate and chloride.
Stability in storage
The transparent light greenish yellow orthorombic crystals contain 44% NaOCl by weight and melt at 25–27 °C. The compound decomposes rapidly at
room temperature, so it must be kept under refrigeration. At lower temperatures, however, it is quite stable: reportedly only 1% decomposition after
360 days at 7 °C.
Further drying
Sodium hypochlorite Dihydrate was claimed to show only 6% decomposition after 13.5 months storage at −25 °C.
Sodium hypochlorite Anhydrous forms by vacuum drying at about 50 °C, yielding a solid that showed no decomposition after 64 hours at −25 °C.
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