Stereochemistry

Question 1

Stereoisomers

Answer 1

isomers that have same formula and connectivity but differ in the position of the atoms in space. They possess one or more stereocenters

Question 2

Stereocenter

Answer 2

a carbon atom bearing 4 different atoms or group of atoms

Question 3

Chiral

Answer 3

any molecule that is nonsuperposable with its mirror image

Question 4

Enantiomers

Answer 4

stereoisomers that are non superimposable mirror images

Properties:
have same chemical and physical properties in an achiral environment but they differ on the sign of rotation of plane polarized light
Opposite configuration at all chirality centers

Question 5

Racemic mixture

Answer 5

a 1:1 (equimolar) mixture of two enantiomers

Question 6

Optically Active

Answer 6

the ability of some compounds to rotate plane polarized light

Question 7

Configuration of Stereocenters

Answer 7

Priority is based on the atomic number, i.e. H has lower priority than Cl. But methyl and ethyl both are attached to the stereocenter through carbon! In these cases, priority assignments proceed outward, to the next atoms. The Methyl carbon has 3 Hs attached while the Ethyl carbon has 2Hs and and a carbon (the terminal methyl group). Therefore, the latter gets higher priority.

Question 8

Diastereomers

Answer 8

stereoisomers that are non-superimposable non-mirror images

Properties:
have different chemical and physical properties in any type of environment
opposite configurations at some chirality centers

Question 9

E-Z system

Answer 9

(E)- : the higher priority groups are on the opposite side of the double bond
(Z)- : the higher priority groups are on the same side of the double bond

Question 10

Confirmations

Answer 10

Different 3-D position for the same molecule