Chapter 5, Problem 44P

(a)

Interpretation Introduction

Interpretation:

Condensed structures and the systematic names for all the alkenes of given compound $C_6{H}_{12}$ has to be determined.

Concept introduction:

• Molecular structure is the arrangement of chemical bonds between atoms in a molecule (or in an ion or radical with multiple atoms), specifically which atoms are chemically bonded to what other atoms with what kind of chemical bond.  From the IUPAC name of compound its structure can be easily drawn.
• IUPAC name consists of three parts in major namely Prefix suffix and root word.
• Prefix represents the substituent present in the molecule and its position in the root name.
• Suffix denotes the presence of functional group if any in the molecule. It can be an alkene, alkyne, alcohol, carboxylic acid, alcohol etc.
• For alkenes, suffix will be ‘ene’.
• Root word represents the longest continuous carbon skeleton of the organic molecule.
• When a molecule consists of cyclic structure, the root word of the molecule is prefixed with cyclo, if it is two cyclic structure combined then prefixed with bicyclo.
• E-Z designators are used as like cis-trans terminology for non-similar groups attached alkenes.
• In E-Z designations, the groups attached to vinylic positions are checked by their priority on the basis of higher molecular weight.  If the higher priority groups are on the same sides, then the configuration is designated as Z.  If the higher priority groups are on the opposite sides, then the configuration is designated as E.
• Condensed Formula: Molecular formula where the symbols of atoms are listed in order as they appear in the respective molecular structure with bonded dash omitted or limited it is called the condensed structure.

(b)

Interpretation Introduction

Interpretation:

The E and Z isomers of alkenes should be identified for the given compound with the molecular formula $C_6{H}_{12}$.

Concept introduction:

• Molecular structure is the arrangement of chemical bonds between atoms in a molecule (or in an ion or radical with multiple atoms), specifically which atoms are chemically bonded to what other atoms with what kind of chemical bond.  From the IUPAC name of compound its structure can be easily drawn.
• IUPAC name consists of three parts in major namely Prefix suffix and root word.
• Prefix represents the substituent present in the molecule and its position in the root name.
• Suffix denotes the presence of functional group if any in the molecule. It can be an alkene, alkyne, alcohol, carboxylic acid, alcohol etc.
• For alkenes, suffix will be ‘ene’.
• Root word represents the longest continuous carbon skeleton of the organic molecule.
• When a molecule consists of cyclic structure, the root word of the molecule is prefixed with cyclo, if it is two cyclic structure combined then prefixed with bicyclo.
• E-Z designators are used as like cis-trans terminology for non-similar groups attached alkenes.
• In E-Z designations, the groups attached to vinylic positions are checked by their priority on the basis of higher molecular weight.  If the higher priority groups are on the same sides, then the configuration is designated as Z.  If the higher priority groups are on the opposite sides, then the configuration is designated as E.

(c)

Interpretation Introduction

Interpretation:

Most stable alkenes has to be identified.

Concept introduction:

The amount of heat released in a hydrogenation reaction is known as heat of hydrogenation$\left(\Delta H^0\right)$.

The most stable alkene has the smallest heat of hydrogenation.

The stability of an alkene increases as the number of alkyl substituents bonded to its $s{p}^2$ carbon increases.

The stability of an alkene increases as the number of hydrogen bonded to its $s{p}^2$ carbon decreases.

(d)

Interpretation Introduction

Interpretation:

Least stable alkene has to be identified.

Concept introduction:

The amount of heat released in a hydrogenation reaction is known as heat of hydrogenation$\left(\Delta H^0\right)$.

The most stable alkene has the smallest heat of hydrogenation.

The stability of an alkene increases as the number of alkyl substituents bonded to its $s{p}^2$ carbon increases.

The stability of an alkene increases as the number of hydrogen bonded to its $s{p}^2$ carbon decreases.