Stereochemistry

Organic Chemistry, Review of Stereochemistry, Prof. Robert Batey, rapscallion 1

Chiral Compounds Stereogenic centres: we will be in particular concerned with stereogenic carbon atoms. Consider an sp3 hybridized carbon which has four contrastive substituents on it. It is can exist in two contrary 3-dimensional arrangements that ar related to each other as non-superimposible reverberate images. These two different compounds are said to be enantiomers, and are an example of stereoisomerism. c Enantiomer 1 d C b a mirror To convince ourselves that they are therefore different, consider rotating enantiomer 2 about the axis a b C c Enantiomer 2 d

axis
b a C c d rotate by 180° d c C b a which we can redraw as: b d C c a

b d C

c a d

c C

b a

Enantiomer 1

Enantiomer 2

notice how that although the dâ€"Câ€"a groups can be superimposed, this leaves the b and the c groups swapped round in the two enantiomers, i.e. they are different compounds

Organic Chemistry, Review of Stereochemistry, Prof. Robert Batey, Page 2

Drawing Chiral Compounds c d C b a is equivalent to b d C c a (since the wedged and dash bonds are perpendicular to the plane of the paper)

To lay down a 3-D sense, practice rotating molecules either around bonds or other axes.



For example, each of the following structures are the aforesaid(prenominal) enantiomer, they just differ in their orientation on the scallywag (for each step a rotation about a bond or axis has occurred). (The use of molecular models is in particular helpful !!!) c d C b c C d a b a b d C c a c b C d a

a c C b d

d c C
c a C d b a b

a b

d c C a b
b a C c d

d b C c a
d c C

b d C

c a

Question: For each step, what was the axis of rotation, and the tumble and direction (clockwise/counterclockwise) of the rotation?

Organic Chemistry, Review of Stereochemistry, Prof. Robert Batey, Page 3

Cahn Ingold Prelog congregation Rank groups on the stereogenic centre as 1 = highest, 2, 3, 4 (lowest, usually H) using the following rules...If you want to get a full essay, order it on our website: Ordercustompaper.com



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