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Le Bel-van't Hoff rule states that for a structure with n asymmetric carbon atoms, there is a maximum of 2 n different stereoisomers possible. As an example, D-glucose is an aldohexose and has the formula C 6 H 12 O 6. Four of its six carbon atoms are stereogenic, which means D-glucose is one of 2 4 =16 possible stereoisomers. [20] [21]
Dextrose monohydrate is the hydrated form of D-glucose, meaning that it is a glucose molecule with an additional water molecule attached. [38] Its chemical formula is C 6 H 12 O 6 · H 2 O. [38] [39] Dextrose monohydrate is also called hydrated D-glucose, and commonly manufactured from plant starches.
For example, D-glucose forms an α crystal that has specific rotation of +112° and melting point of 146 °C, as well as a β crystal that has specific rotation of +19° and melting point of 150 °C. [4] The linear form does not crystallize, and exists only in small amounts in water solutions, where it is in equilibrium with the closed forms. [4]
The number of open chain stereoisomers for an aldose monosaccharide is larger by one than that of a ketose monosaccharide of the same length. Every ketose will have 2 (n−3) stereoisomers where n > 2 is the number of carbons. Every aldose will have 2 (n−2) stereoisomers where n > 2 is the number of carbons. These are also referred to as ...
Stereochemistry, a subdiscipline of chemistry, studies the spatial arrangement of atoms that form the structure of molecules and their manipulation. [1] The study of stereochemistry focuses on the relationships between stereoisomers, which are defined as having the same molecular formula and sequence of bonded atoms (constitution) but differing in the geometric positioning of the atoms in space.
As an example, four of the carbon atoms of the aldohexose class of molecules are asymmetric, therefore the Le Bel–Van 't Hoff rule gives a calculation of 2 4 = 16 stereoisomers. This is indeed the case: these chemicals are two enantiomers each of eight different diastereomers : allose , altrose , glucose , mannose , gulose , idose , galactose ...
However, the stereoisomers produced may also give a meso compound, which is an achiral compound that is superposable on its mirror image; the presence of a meso compound will reduce the number of possible stereoisomers. [4] Since a meso compound is superposable on its mirror image, the two "stereoisomers" are actually identical.
Isomeric relationships form a hierarchy. Two chemicals might be the same constitutional isomer, but upon deeper analysis be stereoisomers of each other. Two molecules that are the same stereoisomer as each other might be in different conformational forms or be different isotopologues. The depth of analysis depends on the field of study or the ...