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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]
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 ...
In chemistry, isomers are molecules or polyatomic ions with identical molecular formula – that is, the same number of atoms of each element – but distinct arrangements of atoms in space. [1] Isomerism refers to the existence or possibility of isomers. Isomers do not necessarily share similar chemical or physical properties.
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.
Each stereocenter gives rise to two different configurations and thus typically increases the number of stereoisomers by a factor of two. Diastereomers differ from enantiomers in that the latter are pairs of stereoisomers that differ in all stereocenters and are therefore mirror images of one another. [ 3 ]
[2] [3] Stereocenters can exist on chiral or achiral molecules; stereocenters can contain single bonds or double bonds. [1] The number of hypothetical stereoisomers can be predicted by using 2 n, with n being the number of tetrahedral stereocenters; however, exceptions such as meso compounds can reduce the prediction to below the expected 2 n. [4]
A molecule may contain any number of stereocenters and any number of double bonds, and each usually gives rise to two possible isomers. A molecule with an integer n describing the number of stereocenters will usually have 2 n stereoisomers, and 2 n−1 diastereomers each having an associated pair of enantiomers.
In stereochemistry, an asymmetric carbon is a carbon atom that is bonded to four different types of atoms or groups of atoms. [1] [2] The four atoms and/or groups attached to the carbon atom can be arranged in space in two different ways that are mirror images of each other, and which lead to so-called left-handed and right-handed versions (stereoisomers) of the same molecule.