Chapter 12, Problem 12.27P

12-27 Explain why each name is incorrect and then write a correct name.

1. 2-Ethyl-l-propene
2. 5-lsopropylcyclohexene
3. 4-Methyl-4-hexene
4. 2-sec-Butyl-l-butene
5. 6,6-Dimethylcyclohexene
6. 2-Ethyl-2-hexene

Interpretation Introduction

(a)

Interpretation:

To identify the error in name of the given compound and write the correct IUPAC names.

Concept Introduction:

The rules to write the IUPAC names are as follows-

• The longest carbon chain is identified, and the root name is given accordingly.
• All the substituents attached to the root chain are determined.
• The position of the substituents is so assigned that the sum of their positions comes to be the least of all possible positions.
• The prefix di, tri, tetra is used if the same substituent is present two, three and four times respectively.
• All the substituents in the name are written in alphabetical order.
• For a cyclic hydrocarbon the prefix cyclo- is used.

Answer to Problem 12.27P

2-Methyl-but-1-ene.

Explanation of Solution

2-Ethyl-1-propene.

Error- longest chain not correctly located.

Correct name-

2-Methyl-but-1-ene.

Interpretation Introduction

(b)

Interpretation:

To identify the error in name of the given compound and write the correct IUPAC names.

Concept Introduction:

The rules to write the IUPAC names are as follows-

• The longest carbon chain is identified, and the root name is given accordingly.
• All the substituents attached to the root chain are determined.
• The position of the substituents is so assigned that the sum of their positions comes to be the least of all possible positions.
• The prefix di, tri, tetra is used if the same substituent is present two, three and four times respectively.
• All the substituents in the name are written in alphabetical order.
• For a cyclic hydrocarbon the prefix cyclo- is used.

Answer to Problem 12.27P

4-Isopropylcyclohexene.

Explanation of Solution

5-Isopropylcyclohexene.

Error- position of the substituent not correctly mentioned.

Correct name-

4-Isopropylcyclohexene.

Interpretation Introduction

(c)

Interpretation:

To identify the error in name of the given compound and write the correct IUPAC names.

Concept Introduction:

The rules to write the IUPAC names are as follows-

• The longest carbon chain is identified, and the root name is given accordingly.
• All the substituents attached to the root chain are determined.
• The position of the substituents is so assigned that the sum of their positions comes to be the least of all possible positions.
• The prefix di, tri, tetra is used if the same substituent is present two, three and four times respectively.
• All the substituents in the name are written in alphabetical order.
• For a cyclic hydrocarbon the prefix cyclo- is used.

Answer to Problem 12.27P

3-Methyl-2-hexene.

Explanation of Solution

4-Methyl-4-hexene.

Error- position of the double bond not correctly mentioned.

Correct name-

3-Methyl-2-hexene.

Interpretation Introduction

(d)

Interpretation:

To identify the error in name of the given compound and write the correct IUPAC names.

Concept Introduction:

The rules to write the IUPAC names are as follows-

• The longest carbon chain is identified, and the root name is given accordingly.
• All the substituents attached to the root chain are determined.
• The position of the substituents is so assigned that the sum of their positions comes to be the least of all possible positions.
• The prefix di, tri, tetra is used if the same substituent is present two, three and four times respectively.
• All the substituents in the name are written in alphabetical order.
• For a cyclic hydrocarbon the prefix cyclo- is used.

Answer to Problem 12.27P

2-Ethyl-3-methyl -1-pentene.

Explanation of Solution

2-sec-butyl-1-butene.

Error- longest chain not correctly determined.

Correct name-

2-Ethyl-3-methyl -1-pentene.

Interpretation Introduction

(e)

Interpretation:

To identify the error in name of the given compound and write the correct IUPAC names.

Concept Introduction:

The rules to write the IUPAC names are as follows-

• The longest carbon chain is identified, and the root name is given accordingly.
• All the substituents attached to the root chain are determined.
• The position of the substituents is so assigned that the sum of their positions comes to be the least of all possible positions.
• The prefix di, tri, tetra is used if the same substituent is present two, three and four times respectively.
• All the substituents in the name are written in alphabetical order.
• For a cyclic hydrocarbon the prefix cyclo- is used.

Answer to Problem 12.27P

3,3-Dimethylcyclohexene.

Explanation of Solution

6,6-Dimethylcyclohexene.

Error- position of substituents not correctly determined.

Correct name-

3,3-Dimethylcyclohexene.

Interpretation Introduction

(f)

Interpretation:

To identify the error in name of the given compound and write the correct IUPAC names.

Concept Introduction:

The rules to write the IUPAC names are as follows-

• The longest carbon chain is identified, and the root name is given accordingly.
• All the substituents attached to the root chain are determined.
• The position of the substituents is so assigned that the sum of their positions comes to be the least of all possible positions.
• The prefix di, tri, tetra is used if the same substituent is present two, three and four times respectively.
• All the substituents in the name are written in alphabetical order.
• For a cyclic hydrocarbon the prefix cyclo- is used.

Answer to Problem 12.27P

3-Methyl-3-Heptene.

Explanation of Solution

2-Ethyl-2-hexene.

Error- longest chain not correctly determined.

Correct name-

3-Methyl-3-Heptene.