Q-4-4-4E - Organic Chemistry (Mcmurry)

Question

Name the following substances, including the cis- or trans- prefix:

a)

b)

Step-by-Step Solution

Answer

a) Trans-1chloro 4-methyl cyclohexane

b) Cis-1-ethyl,3-methyl cyclohexane

IUPAC nomenclature

It is a method to give a scientific name to the organic compounds recommended by the Indian Union of Pure and Applied Chemistry.

Nomenclature of cycloalkanes

IUPAC rules used for naming of cycloalkanes

• Name the parent cycloalkane 
• Assign numbering to the substituents
• Assign the first number to the bulky group
• Halogens get the first priority
• If both the substituent are on wedge or dash then the cis prefix is used
• If one substituent on the wedge and other on the dash and vice-versa then the trans prefix is used
• Write the name of the molecule in alphabetic

Naming of cycloalkane (a)

1. The parent cycloalkane is cyclohexane
2. The substituents are chloro and methyl
3. Choro occupies 1 position and methyl occupies 4 position
4. One substituent is on the wedge and the other on the dash so trans configuration
5. Hence, IUPAC is trans-1-chloro,4-methyl cyclohexane

     trans-1-chloro,4-methyl cyclohexane

Naming of cycloalkane (b)

1. The parent cycloalkane is cyclohexane
2. The substituents are ethyl and methyl
3. Ethyl occupies 1 position and methyl occupy 3position
4. Both substituent is on the wedge so cis configuration
5. Hence, IUPAC is cis-1-ethyl,3-methyl cyclohexane

         cis-1-ethyl,3-methyl cyclohexane