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20.5.1.7.13.2.3 Variation 3: By Solid Acids

DOI: 10.1055/sos-SD-020-00774

Zhang, M.; Hanson, P. R.Science of Synthesis, (200720930.

Solid acids, associated with an advantageous reaction and purification process, are more important than any other acid catalysts in practical use, and are thus very attractive as transesterification catalysts. The silica gel supported sodium hydrogen sulfate catalyst has been applied in highly selective monoacylations of symmetrical[‌354‌,‌355‌] and unsymmetrical diols (e.g., to give 248)[‌356‌] and selective transesterifications of nonconjugated aliphatic acids in the presence of aromatic acids (Scheme 85).[‌357‌] Both primary and secondary diols are selectively monoacylated in the transesterification of symmetrical diols. For the unsymmetrical diols, this method affords greater yields of monoacetate products and higher selectivity for primary hydroxy groups over secondary and phenolic groups than more traditional methods of acetylation. This method of selective transesterification is simple, practical, and reaction workup consists of a simple filtration process.

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