Naming aldoses

General class Number of carbon atoms Formula Trivial name Aldose Ketose... 

Monosaccharides belong to one of two families, namely aldoses or ketoses. Typical of these are the two structural isomers glucose and fructose (10.3). 

Monosaccharides of the polyhydroxyalkanal type have the class name aldose and as individual representatives with up to six carbon atoms the trivial names compiled in Table 15. 

As shown for the aldotetroses an aldose belongs to the d or the l series accord mg to the configuration of the chirality center farthest removed from the aldehyde func tion Individual names such as erythrose and threose specify the particular arrangement of chirality centers within the molecule relative to each other Optical activities cannot be determined directly from the d and l prefixes As if furns ouf bofh d eryfhrose and D fhreose are levorofafory buf d glyceraldehyde is dexfrorofafory... 

Derivatives of aldoses in which the terminal aldehyde function is oxidized to a car boxylic acid are called aldonic acids Aldonic acids are named by replacing the ose ending of the aldose by omc acid Oxidation of aldoses with bromine is the most com monly used method for the preparation of aldonic acids and involves the furanose or pyranose form of the carbohydrate... 

The reaction of aldoses with nitric acid leads to the formation of aldaric acids by oxidation of both the aldehyde and the terminal primary alcohol function to carboxylic acid groups Aldaric acids are also known as saccharic acids and are named by substi tutmg aric acid for the ose ending of the corresponding carbohydrate... 

Ketoses are characterized by the ending ulose m their name Most nat urally occurring ketoses have their carbonyl group located at C 2 Like aldoses ketoses cyclize to hemiacetals and exist as furanose or pyranose forms... 

Fischer projections and, 977-978 glycosides and, 989-990 l- 4 links in, 997-998 origin of name. 973 photosynthesis of, 973-974 see also Aldose, Monosaccharide vaccines from, 1004-1005 Carbon, ground-state electron configuration of, 6... 

The basis for the name is the structure of the parent monosaccharide in the acyclic form. Charts I and IV (2-Carb-10) give trivial names for parent aldoses and ketoses with up to six carbon atoms. 2-Carb-8.2 and 2-Carb-10.3 describe systematic naming procedures. 

Chart I. Trivial names (with recommended three-letter abbreviations in parentheses) and structures (in the aldehydic, acyclic form) of the aldoses with three to six carbon atoms. Only the D-forms are shown the L-forms are the mirror images. The chains of chiral atoms delineated in bold face correspond to the configurational prefixes given in italics below the names... 

Mirror images a-o-glucopyranose-4Ci (upper) and a-L-glucopyranose-1C4 (lower) 2-Carb-8. Aldoses 2-Carb-8.1. Trivial names... 

The aldoses with three to six carbon atoms have trivial names which are given, together with the formulae in the Fischer projection, in Chart I (2-Carb-2.2). (See also the alphabetical listing of trivial names in the Appendix.)... 

Systematic names are formed from a stem name and a configurational prefix or prefixes. The stem names for the aldoses with three to ten carbon atoms are triose,... 

Note 2. Since all aldoses up to the hexoses have trivial names that are preferred, the systematic names apply only to the higher aldoses. However, the configurational prefixes are also used to name ketoses (see below) and other monosaccharides. 

Systematic names for individual dialdoses are formed from the systematic stem name for the corresponding aldose (see 2-Carb-8.2), but with the ending odialdose instead of ose , and the appropriate configurational prefix (Chart I). A choice between the two possible aldose parent names is made on the basis of 2-Carb-2.2.2. 

The stem names are formed from the corresponding aldose stem names (2-Carb-8.2) by replacing the ending -ose with -ulose , preceded by the locant of the carbonyl group, e.g. hex-3-ulose. The chain is numbered so that the carbonyl group receives the lowest possible locant. If the carbonyl group is in the middle of a chain with an odd number of carbon atoms, a choice between alternative names is made according to 2-Carb-2.2.2. 

In a biochemical context, the naming of aldoketoses as dehydro aldoses is widespread. Thus D-xy/o-hexopyranos-4-ulose would be termed 4-dehydro-D-glu-cose. This usage of dehydro can give rise to names which are stereochemically redundant, and should not be employed for naming derivatives. 

The name of an aldose derivative in which the aldehyde group has been replaced by a terminal CH3 group is derived from that of the appropriate alditol (see 2-Carb-19) by use of the prefix deoxy- . 

Replacement of a hydroxy oxygen atom of an aldose or ketose, or of the oxygen atom of the carbonyl group of the acyclic form of an aldose or ketose, by sulfur is indicated by placing the prefix thio , preceded by the appropriate locant, before the systematic or trivial name of the aldose or ketose. 

Alditols are named by changing the suffix -ose in the name of the corresponding aldose into -itol . 

Aldonic acids are divided into aldotrionic acid, aldotetronic acids, aldopentonic acids, aldohexonic acids, etc., according to the number of carbon atoms in the chain. The names of individual compounds of this type are formed by replacing the ending -ose of the systematic or trivial name of the aldose by -onic acid . 

An intramolecular ether (commonly called an intramolecular anhydride), formally arising by elimination of water from two hydroxy groups of a single molecule of a monosaccharide (aldose or ketose) or monosaccharide derivative, is named by attaching the (detachable) prefix anhydro- preceded by a pair of locants identifying the two hydroxy groups involved. 

In clinical chemistry however, these systems have not been differentiated as yet. Since the oxidation of an alcohol corresponds to the reduction of a ketose or an aldose, the designations ketose reductase and aldose reductase, respectively, were suggested (H4, W14). In this paper however, the enzyme or enzyme system will be named polyol or sorbitol dehydrogenase (SDH), although the latter expression does not characterize exacdy the enzyme s function in a general biochemical sense. But sorbitol or fructose have been commonly used as substrates in clinical chemical investigations. 

All carbohydrates can exist in either of these two forms and the prefix of D or L only refers to the configuration around the highest numbered asymmetric carbon atom. Enantiomers have the same name (e.g. D-glucose and L-glucose) and are chemically similar compounds but have different optical properties. The majority of naturally occurring monosaccharides, whether they be aldoses or ketoses, are of the D configuration. 

The carbonyl group in glucose and ribose is an aldehyde such compounds are termed aldoses. Fructose, by contrast, has a ketone group and is therefore classified as a ketose. Glucose could also be termed an aldohexose and fructose a ketohexose, whereas ribose would be an aldopentose, names which indicate both the number of carbons and the nature of the carbonyl group. Another aspeet of nomenclature is the use of the suffix -ulose to indicate a ketose. Fructose could thus be referred to as a hexulose, though we are more likely to see this suffix in the names of specific sugars, e.g. ribulose is a ketose isomer of the aldose ribose. 

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