Aldose simplest

Aldose sugars make up a large part of the carbohydrate family, but the ones that are really worth knowing are part of the D-family. The simplest of these D-sugars is the triose glyceraldehyde. From there you have 2 tetroses, 4 pentoses, and 8 hexoses. Each of these aldose sugars has an enantiomer. 

All the monosaccharides except dihydroxyacetone contain one or more asymmetric (chiral) carbon atoms and thus occur in optically active isomeric forms (pp. 17-19). The simplest aldose, glyceraldehyde, contains one chiral center (the middle carbon atom) and therefore has two different optical isomers, or enantiomers (Fig. 7-2). 

The simplest carbohydrates, sometimes referred to as monosaccharides, or sugars, are either polyhydroxyaldehydes (aldoses) or polyhydroxyketones (ketoses). They can be derived from polyalcohols (polyols) by oxidation of one carbinol group to a carbonyl group. For example, the simple three-carbon triol, glycerol, can be converted either to the aldotriose, glyceraldehyde, or to the ketotriose, dihydroxyacetone, by loss of two hydrogens (fig. 12.1). 

The simplest carbohydrates are the monosaccharides which under specified conditions are structurally characterised as polyhydroxy aldehydes or polyhydroxy ketones these are termed aldoses and ketoses respectively. Aldoses and ketoses are sub-classified, according to the number of carbons present in each molecule, into aldotetroses, aldopentoses, aldohexoses, etc., or ketotetroses, ketopentoses, etc. 

Glyoeraldehydo, the simplest aldose, has only one chiratity center and thm ha. i two enantiomeric [/nirror-unajfe) forms. Only Ibe dexrrorowttvy ei B tiomer occurs naturally, however. That is, a sample of naturally occurrinf glyccraldohyde placed in a polarimeter rotates plane-polarized light in t clockwise direction, denoted <+). 

Dihydroxyacetone is the simplest ketose. The stereochemical relation between d-ketoses containing as many as six carbon atoms are shown in Figure 11.3. Note that ketoses have one fewer asymmetric center than do aldoses with the same number of carbons. d-Fructose is the most abundant ketohexose. 

CAS 56-82-6. IKK IUd 1,0010. Isomeric with dihydroxyacetone. It is produced by the oxidation of sugars in the body. As the simplest aldose, the conformation of d- and L-glyceraldehydes has been designated the reference standard for d- and L-carbohy-drates and derivatives. 

The building blocks of all carbohydrates are the simple sugars called monosaccharides. A monosaccharide can be a polyhydroxy aldehyde (aldose) or a polyhydroxy ketone (ketose). The simplest monosaccharides contain three carbon atoms and are called trioses (tri meaning three ). Glyceraldehyde is the aldose with three carbons (an aldotriose), and dihydroxy acetone is the ketose with three carbon atoms (a ketotiiose). Figure 16.1 shows these molecules. 

The simplest carbohydrate is the aldotriose, glyceraldehyde (Fig. 3-1). The 4-carbon aldoses are related to D- and L-glyceraldehyde and can be viewed as having been stracturaUy derived from them by the introduction of a hydroxylated chiral carbon atom between C-1 and C-2. Thus there are four aldotetroses. Two simple aldopentoses can be derived stmcturally from each of the fom aldotetroses described, making a total of eight aldopentoses. 

Aldoses polyhydroxyaldehydes, one of the two main subdivisions of the monosaccharides (the other is the ketoses see Carbohydrates). A. are characterized by a terminal aldehyde group -CHO, which is always given the number 1 in systematic nomenclature. The A. are formally derived from their simplest representative, glyceraldehyde, by chain extension. According to the number of carbon atoms in their chain, they are classified as trioses, tetroses, etc. The pentoses and hexoses are particularly important metaboli-cally. 

The simplest aldose. Configurational standard for carbohydrates. In aq. soln., undergoes equilibration with dimers and with l,3-Dihydroxy-2-propanone, D-710 via the enediol tautomer. 

Glyceraldehyde is the simplest aldose, and dihydroxyacetone is the simplest ketose. Each is related to glycerol in that each has a carbonyl group in place of one of the hydroxyl groups. 

You will notice that glyceraldehyde, the simplest aldose, has one stereogenic carbon atom (C-2) and hence can exist in two enantiomeric forms. 

The term carbohydrate originates from the fact that many but not all, members of this class have the general molecular formula C H2 0 and thus were once considered to be "hydrates of carbon." Examination of the structures of carbohydrates readily reveals that this view is inaccurate, but use of the term persists. The simplest carbohydrates are either polyhydroxy aldehydes, which have the general structure 1 and are referred to as aldoses, or polyhydroxy ketones, which have the general structure 2 and are called ketoses. Such simple carbohydrates are termed monosaccharides. 

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