How determination of chirality in Meso compounds ?

Identifying planes of symmetry in Fischer formulas is relatively easy, since they are planar representations.

The following illustrations show examples of both chiral and achiral molecules.

The process of assigning absolute configurations to the chiral centers in molecules containing two or more of them is basically an extension of the process followed for molecules containing only one. However, it helps to isolate the chiral centers and deal with one at a time to avoid confusion.

The following example illustrates this point. In this example we have numbered the carbon atoms in the

main chain according to IUPAC rules that will be studied later.

We have also marked the chiral carbons with asterisks.

Once the chiral centers have been identified, we focus on one at a time (shown as a red dot). First, we isolate carbon-2, then we assign priorities to the groups bonded to it, and assign configuration. In this case the configuration of carbon-2 turns out to be (R). A similar process for carbon-3 also leads to (R) configuration.

The IUPAC notation used to indicate the configurations at carbons 2 and 3 is therefore (2R, 3R).

Related Questions:

(1) Although anti conformation is more stable than the gauch conformation but in some cases gauch or skew conformation is more stable than the anti confirmation why?

(2) Arrange the following in the order of their increasing order of expected enol content. H3C-CO-CH2-CHO, H3C-CO-CH3, H3C-CHO and H3C-CO-CH2-CO-CH3 .

(3) Write total fuctional isomers of molecular formula C5H10.

(4) How to find number of stereoisomers in a large compound containing chiral centres ?.

(5) How to find number of stereoisomers in a large compound (polyenes) containing double bonds?

(6) How do you calculate the number of all possible structural isomers for alkanes?

(7) How many cyclic isomers possible of (C6H12) Hexene?

(8) How many cyclic isomers possible of (C5H10) pentene?

(9) Write the major and minor product of hydration of 1-Methylcyclopent-1-ene in acidic medium?

(10) Why enol form of Beta Dicarbonyl compound more stable than those of monocarbonyl compounds?

The term stereogenic center or stereocenter:

A stereogenic center is defined as an atom on which an interchange of any two atoms or groups result in a new stereoisomer, When the new stereoisomers is an enantiomer ,the stereocenter is called chiral center. All stereocenters are not tetrahedral.

First and second are enantiomers (non superimposible mirror images), Hence the steriocentre is a chiral centre.

III and IV are not enantiomers. they are diasteriomers hence in this case sterio centres are not chiral centres. Also these are not tetrahedral. Thus, all chiral centres are sterio centres but all steriocentres are not chiral centres. If a molecule contains only one chiral centres it must be chiral. Molecule containing two or more 

chiral centres may or may not be chiral. For example: meso tartaric acid has two chiral centres but it is achiral.

Realated Questions:

(1) How many cyclic isomers possible of (C6H12) Hexene?

(2) How many cyclic isomers possible of (C5H10) pentene?

(3) Write the major and minor product of hydration of 1-Methylcyclopent-1-ene in acidic medium?

(4) Why enol form of Beta Dicarbonyl compound more stable than those of monocarbonyl compounds?

(5) Why enol form of phenol is more stable than its keto isomers?

(6) What is Imine-Enamine tautomerism?

(7) The term Asymmetric center and chiral center :

The term Asymmetric center and chiral center :

Three terms are used to designate, a carbon atom bonded tetrahedrally to four different substituents in a chiral molecule: 

Asymmetric atom, chiral center or stereocenter.

Let us understand chiral and achiral center taking few more examples.

Related Questions:

(1) Although anti conformation is more stable than the gauch conformation but in some cases gauch or skew conformation is more stable than the anti confirmation why?

(2) Arrange the following in the order of their increasing order of expected enol content. H3C-CO-CH2-CHO, H3C-CO-CH3, H3C-CHO and H3C-CO-CH2-CO-CH3 .

(3) Write total fuctional isomers of molecular formula C5H10.

(4) How to find number of stereoisomers in a large compound containing chiral centres ?.

(5) How to find number of stereoisomers in a large compound (polyenes) containing double bonds?

(6) How do you calculate the number of all possible structural isomers for alkanes?

(7) How many cyclic isomers possible of (C6H12) Hexene?

(8) How many cyclic isomers possible of (C5H10) pentene?

(9) Write the major and minor product of hydration of 1-Methylcyclopent-1-ene in acidic medium?

(10) Why enol form of Beta Dicarbonyl compound more stable than those of monocarbonyl compounds?

(11) Why enol form of phenol is more stable than its keto isomers?