Carb-21. Ketoaldonic Acids

Names of individual ketoaldonic acids are formed by replacing the ending -ulose of the corresponding ketose by -ulosonic acid , preceded by the locant of the ketonic carbonyl group. The anion takes the ending -ulosonate . The numbering starts at the carboxy group. 

In glycosides derived from ketoaldonic acids, the ending is -ulosidonic acid , with appropriate ring-size infix, e.g. -ulopyranosidonic acid . 

D-etyfhro-Pent-2-ulosonic acid D-arab/no-Hex-5-ulosonic acid 

The last of the above examples is one of the possible forms of the compound referred to by the three-letter symbol Kdo (formerly the abbreviation KDO, from the previously allowed trivial name ketodeoxyoctonic acid). Similarly the symbol Kdn for the C9 sugar 3-deoxy-D-g/ycero-D-gaiacro-non-2-ulopyranosonic acid is widely used. 

Esters, lactones, lactams, acyl halides etc. are named by modifying the ending -ic acid as described for aldonic acids (2-Carb-20.2). 

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Oxo carboxylic acids formally derived from aldonic acids by replacement of a secondary CHOH group by a carbonyl group are called ketoaldonic acids (see 2-Carb-21). 

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