Disaccharides their peracetates

The conventional mass spectra obtained from saccharides transformed into their OTMS and -OCH3 derivatives were interpreted by using labeled derivatives. Systematic studies had never been performed on -OAc derivatives. However, in 1975, Das and Thayumanavan [230] studied various peracetylated disaccharides by their IKE spectra to resolve the ambiguity appearing in the El mass spectra of the isomeric peracetates of trehalose, sophorose, kojibiose, laminaribiose, maltose, melibiose and gentiobiose, all characterized by the same molecular weights (678). 

Peracetates of aldoses, disaccharides, and methyl glycosides have been obtained in good yields by reaction of the trimethylsilylated sugars with iron(III) chloride-acetic anhydride without change in their stereochemistry. The same reaction on ketoses produced dehydration products only. 

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