Isomerism

Question 1

Stereochemistry

Answer 1

Branch of chemistry that studies the three dimensional arrangement of molecules and the effect of this in a chemical reaction.

NOTE: We need at least one sp3- hybridized carbon

Question 2

Isomers

Answer 2

Two or more compound that has a same molecular formula but different arrangement of atoms or molecules and different properties.

Question 3

Alkyl Halide

Answer 3

R-X

Alkyl Group bonded to a Halogen group.

Question 4

Isomers differ in: (Enumeration)

Answer 4

1. Arrangement in bonds
2. Configuration (Change of side chain position)
3. Conformation (Temporary spatial arrangement)

Question 5

Structural/Constitutional Isomers

Answer 5

Same molecular formula but different in arrangement or connectivity

Question 6

Stereoisomers

Answer 6

Same structure and same molecular formula but different arrangement of molecules in space

Question 7

SKELETAL/CHAIN ISOMERS

Answer 7

Same molecular formula, Different in structure, different in parent name, different in branching

Question 8

Positional Isomers

Answer 8

Same molecular formula, different in structure, Same in parent name, different in branching

Question 9

Functional Isomers

Answer 9

Same molecular formula, different in structure, different in functional groups,

Question 10

Conformers

Answer 10

Stereoisomerism in which the isomers can be interconverted just by rotations about formally
single bonds about σ bonds.

Question 11

Acyclic Conformers

Answer 11

Chair shaped

Question 12

Cyclic conformers

Answer 12

Boat shaped

Question 13

Newman’s Projection Formula

Answer 13

The two carbon atoms joined by the bond are
represented as two superimposed circles;
however, for representation only one circle is
drawn.

Question 14

Sawhorse Projection Formula

Answer 14

The two carbon atoms are joined by a larger
diagonal line which is taken to be on the plane of
the paper.

Question 15

(Type of Stereoisomers)
Configurational Isomers

Answer 15

Two molecules with the same constitution but
different configuration and the isomers cannot be
interconverted without breaking and remaking
covalent bonds.

Permanent difference

Question 16

(Type of Configurational Isomer)
Geometric Isomers

Answer 16

Result of restricted rotation about a chemical
bond, owing to double bonds or rigid ring
systems in the molecule.

Question 17

(Type of Geometric Isomer)
Cis-Trans System

Answer 17

Isomerism occurs in double bonds and in ring
structure.

Question 18

Configurational Isomers

E/Z system

Answer 18

Isomerism occurs in double bonds for tetrasubstituted alkene.

Cahn-Ingold-Prelog
Z – geometry
E – geometry

Question 19

OPTICAL ISOMERS

Answer 19

Isomers differ in the placement of substituted
groups. Molecules can exist as two isomers that are
non-superimposable,

Question 20

SUPERIMPOSABLE MIRROR IMAGES

Answer 20

Images that coincide at all points when the
images are laid upon each other.

Question 21

NON - SUPERIMPOSABLE MIRROR IMAGES

Answer 21

A molecule whose mirror images are not
superimposable.

Question 22

TYPES OF OPTICAL ISOMERS

Answer 22

ENANTIOMERS
EUTOMER (R)
DISTOMER (S)
DIASTEREOMERS
EPIMERS
ANOMER

Question 23

Enantiomers

Answer 23

● Molecules that are mirror images but non
superimposable.
● Ability of a molecule to rotate plane polarized
light.
● Dextrorotatory (+)
● Levorotatory (-)
● Racemic Mixture

Question 24

Eutomer

Answer 24

● The enantiomer with the desired pharmacological
effect.

Question 25

Distomer(s)

Answer 25

The enantiomer that does not have pharmacological activity or may be responsible
for adverse effect.

Question 26

Diastereomers

Answer 26

● Non-mirror-image,non superimposable
configurational isomers.
● They possess different physicochemical
properties
● Epimers
● Anomers

Question 27

EPIMERS

Answer 27

● Diastereomers whose molecules differ only in the
configuration at one chiral center.

Question 28

ANOMER

Answer 28

These are diastereomers that differ in
configuration at the first chirality center.