The Chemistry of Plant Life

by Roscoe Wilfred Thatcher

THE ALCOHOL GLUCOSIDES

Salicin, C₁₃H₁₈O₇ (glucose + saligenin, or o-oxy benzyl alcohol) is found in the bark, leaves, and flowers of most species of willow, the proportion present depending upon the season of the year, and the sex of the tree. It is used as a remedy against fevers and rheumatism, causing less digestive disturbances than the salicylic acid which is the oxidation product of saligenin and which is sometimes used as a remedy for rheumatism.

Coniferin, C₁₆H₂₂O₈ (glucose and coniferyl alcohol), is found in the bark of fir trees. The coniferyl alcohol obtained from coniferin by hydrolysis can be easily oxidized to vanillin, and is, therefore, the source for the artificial flavoring extract used as a substitute for the true extract of the vanilla bean.

Populin, C₂₀H₂₂O₈ (glucose + saligenin+benzoic acid), found in the bark of poplar trees, is used in medicine as an antipyretic. It can be hydrolyzed, by a special enzyme, into salicin and benzoic acid.

The structure of the two typical closed-ring alcohols which are present in these glucosides is indicated by the following formulas;

THE ALDEHYDE GLUCOSIDES

Salinigrin, C₁₃H₁₆O₇ (glucose and m-oxy benzaldehyde), is found in the bark of one species of willow (Salix discolor). Its isomer, known as helicin (glucose and o-oxy benzaldehyde, or salicylic aldehyde), does not occur naturally in any plant, but is easily produced artificially by the gentle oxidation of salicin. Their relationships are shown on the following formulas;