Quantitative determination with periodate of compounds subject to non-malapradian oxidation. Part I. Methyl ethers of polyhydroxy-compounds
Compounds which give rise to the 2-methyl ether of triose reductone (2-methoxymalonaldehyde) have been reported to undergo non-stoicheiometric ‘over-oxidation’ reactions. The behaviour of four such compounds, 3-O-methyl-D-xylose, 3-O-methyl-D-glucose, (–)-quebrachitol [5-O-methyl-(–)-inositol-(1,2,4/3,5,6)], and (+)-pinitol [6-O-methyl-(+)inositol-(1,2,5/3,4,6)], towards periodate in 0·1N-sulphuric acid at 0°, has been examined. Under these conditions, the methoxymalonaldehyde formed as the result of glycol cleavage reacts stoicheiometrically with periodate: it reduces two molar equivalents of the oxidant and yields one equivalent each of formic and glyoxylic acids. The possible pathways for this oxidation are discussed.