Synthesis of ethylene glycol-silica sodalite

One of the most significant results in solvothermal chemistry reported thus far is the synthesis of silica-sodafite, reported by Bibby and Dale, which has never been prepared in aqueous systems. Ethylene glycol was used as the solvent in this synthesis, and it was shown that ethylene glycol is fiapped in the cage of the sodalite. ... 

To act as an SDA, a molecule must fulfil certain other prerequisites besides stability [5-7]. A critical factor is its solubility in the solvent used (usually water). The potential SDA must possess at least a limited solubility to take part in the reaction. However, if the solubility is too high or if the SDA forms strong hydrogen bonds with water, then its tendency to co-crystallize with the silica will be low and it will prefer to stay in solution. For this reason, alcohols are only weak SDAs, for instance. The fact that ethylene glycol and ethanolamine are grouped with other SDAs for the synthesis of silica sodalite in Fig. Id seems to contradict this conclusion. However, these molecules act as SDAs only in solvothermal synthesis, in which the SDA simultaneously acts as the solvent. 

A new method for the synthesis of silica-rich or pure silica sodalite has been reported using nonaqueous synthesis media such as ethylene glycol or other suitable solvents [6]. The product tends to be silica-rich, and in the absence of aluminum it is pure silica with unit cell composition Sij 2024 2 C2H4(0H)2 Interestingly, the silica sodalite... 

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