A Mnemonic for Carbohydrate Configurations

The task of relating carbohydrate configurations to names requires either a world-class memory or an easily recalled mnemonic. A mnemonic that serves us well here was popularized by Louis F. Fieser and Mary Fieser of Harvard University in their 1956 textbook. Organic Chemistry. As with many mnemonics, it s not clear who actually invented it, and references to this particular one appeared in the chemical education literature before publication of the Fiesers text. The mnemonic has two features (1) a system for setting down all the stereoisomeric o-aldohexoses in a logical order and (2) a way to assign the correct name to each one. 

Once the eight Fischer projections have been written, they are named in order with the aid of the sentence All altruists gladly make gum in gallon tanks. The words of the sentence stand for allose, altrose, glucose, mannose, gulose, idose, galactose, talose. 

An analogous pattern of configurations can be seen in the aldopentoses when they are arranged in the order ribose, arabinose, xylose, lyxose. (RAXL is an easily remembered nonsense word that gives the correct sequence.) This pattern is discernible even in the aldotetroses erythrose and threose. 

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