Chapter 15, Problem 15.26P

(a)

Interpretation Introduction

Interpretation:

The structure of 1,3-dichloropentane has to be drawn and the optical activity has to be determined.

Concept Introduction:

The structure of the compound is given by its systematic name.

To give the structure from the name of the compound, the root name has to be identified.  The root name indicates the number of carbon atoms present in the longest chain.

Then the functional group (suffix) has to be identified.  It indicates whether any functional groups are present in the compound, it also gives whether the compound is an alkane or alkene or alkyne.

The prefix of the name indicates the branched groups and their positions on the carbon chain.

The name of the compound is in the form

Prefix + Root + Suffix

The isomers which are mirror images of each other and are non-superimposable are said to be optical isomers and the isomerism is said to be optical isomerism.  The optical isomers are also called as enantiomers.  The optical isomers which rotate the plane-polarized light are optically active.

The optical isomers are asymmetric and plane of symmetry will be absent.  An organic molecule is said to be chiral when it is bonded to four different groups and is asymmetric.  The carbon atom bonded to four different groups is said to be chiral carbon or asymmetric carbon.  An organic compound is said to be optically active when it contains at least one chiral center.

(b)

Interpretation Introduction

Interpretation:

The structure of 3-chloro-2,2,5-trimethylhexane has to be drawn and the optical activity has to be determined.

Concept Introduction:

The structure of the compound is given by its systematic name.

To give the structure from the name of the compound, the root name has to be identified.  The root name indicates the number of carbon atoms present in the longest chain.

Then the functional group (suffix) has to be identified.  It indicates whether any functional groups are present in the compound, it also gives whether the compound is an alkane or alkene or alkyne.

The prefix of the name indicates the branched groups and their positions on the carbon chain.

The name of the compound is in the form

Prefix + Root + Suffix

The isomers which are mirror images of each other and are non-superimposable are said to be optical isomers and the isomerism is said to be optical isomerism.  The optical isomers are also called as enantiomers.  The optical isomers which rotate the plane-polarized light are optically active.

The optical isomers are asymmetric and plane of symmetry will be absent.  An organic molecule is said to be chiral when it is bonded to four different groups and is asymmetric.  The carbon atom bonded to four different groups is said to be chiral carbon or asymmetric carbon.  An organic compound is said to be optically active when it contains at least one chiral center.

(c)

Interpretation Introduction

Interpretation:

The structure of 1-bromo-1-chlorobutane has to be drawn and the optical activity has to be determined.

Concept Introduction:

The structure of the compound is given by its systematic name.

To give the structure from the name of the compound, the root name has to be identified.  The root name indicates the number of carbon atoms present in the longest chain.

Then the functional group (suffix) has to be identified.  It indicates whether any functional groups are present in the compound, it also gives whether the compound is an alkane or alkene or alkyne.

The prefix of the name indicates the branched groups and their positions on the carbon chain.

The name of the compound is in the form

Prefix + Root + Suffix

The isomers which are mirror images of each other and are non-superimposable are said to be optical isomers and the isomerism is said to be optical isomerism.  The optical isomers are also called as enantiomers.  The optical isomers which rotate the plane-polarized light are optically active.

The optical isomers are asymmetric and plane of symmetry will be absent.  An organic molecule is said to be chiral when it is bonded to four different groups and is asymmetric.  The carbon atom bonded to four different groups is said to be chiral carbon or asymmetric carbon.  An organic compound is said to be optically active when it contains at least one chiral center.