Chapter 2, Problem 2.28P

Explain why each is an incorrect IUPAC name and write the correct IUPAC name for the intended compound.

1. (a) 1,3-Dimethylbutane
2. (b) 4-Methylpentane
3. (c) 2,2-Diethylbutane
4. (d) 2-Ethyl-3-methylpentane
5. (e) 2-Propylpentane
6. (f) 2,2-Diethylheptane
7. (g) 2,2-Dimethylcyclopropane
8. (h) 1-Ethyl-5-methylcyclohexane

Interpretation Introduction

Interpretation:

The reason for the incorrect IUPAC name of the given compound has to be explained also the correct IUPAC name for the intended compound has to be given.

Concept Introduction:

IUPAC nomenclature:

The rules for writing IUPAC system of names is as follows,

1. 1) For an alkane with unbranched chain of carbon atoms, prefix the root word showing the number of carbon atoms ad end the name with –ane.
2. 2) For branched chain alkane, select the longest chain of carbon atoms as the parent chain, its name becomes the root name.
3. 3) Number all the carbon atoms in the parent chain. When a substituent is attached to the chain, the number shows the carbon atom to which the substituent is attached. Use a hyphen in the name to connect the number to the substituent name.
4. 4) Always number the parent chain in such a way that the carbon bearing substituent gets the lower number.
5. 5) If a same substituent is present more than one time, then number the parent chain in such a way that the first encountered substituent gets the lowest number. Prefix di-, tri-, tetra-, penta- and so on to indicate the number of times the substituent occurs. A comma is used to separate position numbers.
6. 6) If there are two or more different substituents, list them in alphabetical order and number the chain from the end that gives the lower number to the substituent encountered first. If there are different substituents in equivalent positions on opposite ends of the parent chain, give the substituent of lower alphabetical order the lower number.
7. 7) Alphabetize the names of the substituents first and then insert these prefixes.
8. 8) Where two or more parent chains of identical lengths are present, the chain with greater number of substituent must be chosen as parent chain.

Explanation of Solution

Given data:

1,3-Dimethylbutane

Correct IUPAC name:

The structure of 1,3-Dimethylbutane is,

The given IUPAC name is incorrect because in the above structure, the longest chain is pentane.

The main carbon chain has five carbon atoms and one methyl group at the second position

Hence, the correct IUPAC name is 2-methylpentane.

Interpretation Introduction

Interpretation:

The reason for the incorrect IUPAC name of the given compound has to be explained also the correct IUPAC name for the intended compound has to be given.

Concept Introduction:

IUPAC nomenclature:

The rules for writing IUPAC system of names is as follows,

1. 1) For an alkane with unbranched chain of carbon atoms, prefix the root word showing the number of carbon atoms ad end the name with –ane.
2. 2) For branched chain alkane, select the longest chain of carbon atoms as the parent chain, its name becomes the root name.
3. 3) Number all the carbon atoms in the parent chain. When a substituent is attached to the chain, the number shows the carbon atom to which the substituent is attached. Use a hyphen in the name to connect the number to the substituent name.
4. 4) Always number the parent chain in such a way that the carbon bearing substituent gets the lower number.
5. 5) If a same substituent is present more than one time, then number the parent chain in such a way that the first encountered substituent gets the lowest number. Prefix di-, tri-, tetra-, penta- and so on to indicate the number of times the substituent occurs. A comma is used to separate position numbers.
6. 6) If there are two or more different substituents, list them in alphabetical order and number the chain from the end that gives the lower number to the substituent encountered first. If there are different substituents in equivalent positions on opposite ends of the parent chain, give the substituent of lower alphabetical order the lower number.
7. 7) Alphabetize the names of the substituents first and then insert these prefixes.
8. 8) Where two or more parent chains of identical lengths are present, the chain with greater number of substituent must be chosen as parent chain.

Explanation of Solution

Given data:

4-Methylpentane

Correct IUPAC name:

The structure of 4-Methylpentane is,

The given IUPAC name is incorrect because in the above structure, the pentane is numbered wrongly.

The main carbon chain has five carbon atoms and one methyl group at the second position

Hence, the correct IUPAC name is 2-methylpentane.

Interpretation Introduction

Interpretation:

The reason for the incorrect IUPAC name of the given compound has to be explained also the correct IUPAC name for the intended compound has to be given.

Concept Introduction:

IUPAC nomenclature:

The rules for writing IUPAC system of names is as follows,

1. 1) For an alkane with unbranched chain of carbon atoms, prefix the root word showing the number of carbon atoms ad end the name with –ane.
2. 2) For branched chain alkane, select the longest chain of carbon atoms as the parent chain, its name becomes the root name.
3. 3) Number all the carbon atoms in the parent chain. When a substituent is attached to the chain, the number shows the carbon atom to which the substituent is attached. Use a hyphen in the name to connect the number to the substituent name.
4. 4) Always number the parent chain in such a way that the carbon bearing substituent gets the lower number.
5. 5) If a same substituent is present more than one time, then number the parent chain in such a way that the first encountered substituent gets the lowest number. Prefix di-, tri-, tetra-, penta- and so on to indicate the number of times the substituent occurs. A comma is used to separate position numbers.
6. 6) If there are two or more different substituents, list them in alphabetical order and number the chain from the end that gives the lower number to the substituent encountered first. If there are different substituents in equivalent positions on opposite ends of the parent chain, give the substituent of lower alphabetical order the lower number.
7. 7) Alphabetize the names of the substituents first and then insert these prefixes.
8. 8) Where two or more parent chains of identical lengths are present, the chain with greater number of substituent must be chosen as parent chain.

Explanation of Solution

Given data:

2,2-Diethylbutane

Correct IUPAC name:

The structure of 2,2-Diethylbutane is,

The given IUPAC name is incorrect because in the above structure, the longest chain is pentane.

The main carbon chain has five carbon atoms and one methyl group and one ethyl group at the third position

Hence, the correct IUPAC name is 3-ethyl-3-methylpentane.

Interpretation Introduction

Interpretation:

The reason for the incorrect IUPAC name of the given compound has to be explained also the correct IUPAC name for the intended compound has to be given.

Concept Introduction:

IUPAC nomenclature:

The rules for writing IUPAC system of names is as follows,

1. 1) For an alkane with unbranched chain of carbon atoms, prefix the root word showing the number of carbon atoms ad end the name with –ane.
2. 2) For branched chain alkane, select the longest chain of carbon atoms as the parent chain, its name becomes the root name.
3. 3) Number all the carbon atoms in the parent chain. When a substituent is attached to the chain, the number shows the carbon atom to which the substituent is attached. Use a hyphen in the name to connect the number to the substituent name.
4. 4) Always number the parent chain in such a way that the carbon bearing substituent gets the lower number.
5. 5) If a same substituent is present more than one time, then number the parent chain in such a way that the first encountered substituent gets the lowest number. Prefix di-, tri-, tetra-, penta- and so on to indicate the number of times the substituent occurs. A comma is used to separate position numbers.
6. 6) If there are two or more different substituents, list them in alphabetical order and number the chain from the end that gives the lower number to the substituent encountered first. If there are different substituents in equivalent positions on opposite ends of the parent chain, give the substituent of lower alphabetical order the lower number.
7. 7) Alphabetize the names of the substituents first and then insert these prefixes.
8. 8) Where two or more parent chains of identical lengths are present, the chain with greater number of substituent must be chosen as parent chain.

Explanation of Solution

Given data:

2-Ethyl-3-methylpentane

Correct IUPAC name:

The structure of 2-Ethyl-3-methylpentane is,

The given IUPAC name is incorrect because in the above structure, the longest chain is hexane.

The main carbon chain has six carbon atoms and two methyl group at the third and fourth position

Hence, the correct IUPAC name is 3,4-dimethylhexane.

Interpretation Introduction

Interpretation:

The reason for the incorrect IUPAC name of the given compound has to be explained also the correct IUPAC name for the intended compound has to be given.

Concept Introduction:

IUPAC nomenclature:

The rules for writing IUPAC system of names is as follows,

1. 1) For an alkane with unbranched chain of carbon atoms, prefix the root word showing the number of carbon atoms ad end the name with –ane.
2. 2) For branched chain alkane, select the longest chain of carbon atoms as the parent chain, its name becomes the root name.
3. 3) Number all the carbon atoms in the parent chain. When a substituent is attached to the chain, the number shows the carbon atom to which the substituent is attached. Use a hyphen in the name to connect the number to the substituent name.
4. 4) Always number the parent chain in such a way that the carbon bearing substituent gets the lower number.
5. 5) If a same substituent is present more than one time, then number the parent chain in such a way that the first encountered substituent gets the lowest number. Prefix di-, tri-, tetra-, penta- and so on to indicate the number of times the substituent occurs. A comma is used to separate position numbers.
6. 6) If there are two or more different substituents, list them in alphabetical order and number the chain from the end that gives the lower number to the substituent encountered first. If there are different substituents in equivalent positions on opposite ends of the parent chain, give the substituent of lower alphabetical order the lower number.
7. 7) Alphabetize the names of the substituents first and then insert these prefixes.
8. 8) Where two or more parent chains of identical lengths are present, the chain with greater number of substituents must be chosen as parent chain.

Explanation of Solution

Given data:

2-Propylpentane

Correct IUPAC name:

The structure of 2-Propylpentane is,

The given IUPAC name is incorrect because in the above structure, the longest chain is heptane.

The main carbon chain has seven carbon atoms and one methyl group at the fourth position

Hence, the correct IUPAC name is 4-methylheptane.

Interpretation Introduction

Interpretation:

The reason for the incorrect IUPAC name of the given compound has to be explained also the correct IUPAC name for the intended compound has to be given.

Concept Introduction:

IUPAC nomenclature:

The rules for writing IUPAC system of names is as follows,

1. 1) For an alkane with unbranched chain of carbon atoms, prefix the root word showing the number of carbon atoms ad end the name with –ane.
2. 2) For branched chain alkane, select the longest chain of carbon atoms as the parent chain, its name becomes the root name.
3. 3) Number all the carbon atoms in the parent chain. When a substituent is attached to the chain, the number shows the carbon atom to which the substituent is attached. Use a hyphen in the name to connect the number to the substituent name.
4. 4) Always number the parent chain in such a way that the carbon bearing substituent gets the lower number.
5. 5) If a same substituent is present more than one time, then number the parent chain in such a way that the first encountered substituent gets the lowest number. Prefix di-, tri-, tetra-, penta- and so on to indicate the number of times the substituent occurs. A comma is used to separate position numbers.
6. 6) If there are two or more different substituents, list them in alphabetical order and number the chain from the end that gives the lower number to the substituent encountered first. If there are different substituents in equivalent positions on opposite ends of the parent chain, give the substituent of lower alphabetical order the lower number.
7. 7) Alphabetize the names of the substituents first and then insert these prefixes.
8. 8) Where two or more parent chains of identical lengths are present, the chain with greater number of substituent must be chosen as parent chain.

Explanation of Solution

Given data:

2,2-Diethylheptane

Correct IUPAC name:

The structure of 2,2-Diethylheptane is,

The given IUPAC name is incorrect because in the above structure, the longest chain is octane.

The main carbon chain has eight carbon atoms and one methyl group and one ethyl group are at the second carbon.

Hence, the correct IUPAC name is 3-ethyl-3-methyloctane.

Interpretation Introduction

Interpretation:

The reason for the incorrect IUPAC name of the given compound has to be explained also the correct IUPAC name for the intended compound has to be given.

Concept Introduction:

IUPAC nomenclature:

The rules for writing IUPAC system of names is as follows,

1. 1) For an alkane with unbranched chain of carbon atoms, prefix the root word showing the number of carbon atoms ad end the name with –ane.
2. 2) For branched chain alkane, select the longest chain of carbon atoms as the parent chain, its name becomes the root name.
3. 3) Number all the carbon atoms in the parent chain. When a substituent is attached to the chain, the number shows the carbon atom to which the substituent is attached. Use a hyphen in the name to connect the number to the substituent name.
4. 4) Always number the parent chain in such a way that the carbon bearing substituent gets the lower number.
5. 5) If a same substituent is present more than one time, then number the parent chain in such a way that the first encountered substituent gets the lowest number. Prefix di-, tri-, tetra-, penta- and so on to indicate the number of times the substituent occurs. A comma is used to separate position numbers.
6. 6) If there are two or more different substituents, list them in alphabetical order and number the chain from the end that gives the lower number to the substituent encountered first. If there are different substituents in equivalent positions on opposite ends of the parent chain, give the substituent of lower alphabetical order the lower number.
7. 7) Alphabetize the names of the substituents first and then insert these prefixes.
8. 8) Where two or more parent chains of identical lengths are present, the chain with greater number of substituent must be chosen as parent chain.

Explanation of Solution

Given data:

2,2-Dimethylcyclopropane

Correct IUPAC name:

The structure of 2,2-Dimethylcyclopropane is,

The ring is numbered incorrectly for the above structure.

The main core of the given compound has a cyclic three membered ring with two methyl groups at one carbon.

Hence, the correct IUPAC name is 1,1-dimethylcylcopropane.

Interpretation Introduction

Interpretation:

The reason for the incorrect IUPAC name of the given compound has to be explained also the correct IUPAC name for the intended compound has to be given.

Concept Introduction:

IUPAC nomenclature:

The rules for writing IUPAC system of names is as follows,

1. 1) For an alkane with unbranched chain of carbon atoms, prefix the root word showing the number of carbon atoms ad end the name with –ane.
2. 2) For branched chain alkane, select the longest chain of carbon atoms as the parent chain, its name becomes the root name.
3. 3) Number all the carbon atoms in the parent chain. When a substituent is attached to the chain, the number shows the carbon atom to which the substituent is attached. Use a hyphen in the name to connect the number to the substituent name.
4. 4) Always number the parent chain in such a way that the carbon bearing substituent gets the lower number.
5. 5) If a same substituent is present more than one time, then number the parent chain in such a way that the first encountered substituent gets the lowest number. Prefix di-, tri-, tetra-, penta- and so on to indicate the number of times the substituent occurs. A comma is used to separate position numbers.
6. 6) If there are two or more different substituents, list them in alphabetical order and number the chain from the end that gives the lower number to the substituent encountered first. If there are different substituents in equivalent positions on opposite ends of the parent chain, give the substituent of lower alphabetical order the lower number.
7. 7) Alphabetize the names of the substituents first and then insert these prefixes.
8. 8) Where two or more parent chains of identical lengths are present, the chain with greater number of substituent must be chosen as parent chain.

Explanation of Solution

Given data:

1-Ethyl-5-methylcyclohexane

Correct IUPAC name:

The structure of 1-Ethyl-5-methylcyclohexane is,

The main core of the given compound has a cyclic six membered ring with one ethyl groups at first carbon and one methyl group at third carbon.

The main carbon chain has six carbon atoms and one methyl group at the second position

Hence, the correct IUPAC name is 1-ethyl-3-methylcyclohexane.