Q19E - Organic Chemistry (Mcmurry)

Question

Give IUPAC names for the following compounds (reddish brown 5 Br; yellow 5 S):

Step-by-Step Solution

Answer

a. cis-1-ethoxy,3-methyl cyclohexane

b. E-2(o-bromo phenyl)-2,3-ethoxy butane

c. S-1-cyclopential ethane thiol

Step 1: IUPAC nomenclature

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

Step 2: Nomenclature of epoxide, thiol, and sulfide

IUPAC rules used for naming:

1. Select the longest carbon chain

2. the parent alkane chain and prefix cyclo are used

3. Assign numbering to the substituents

4. Assign the first number to the hydroxy group

5. Halogens get the priority than others substituent 

6. If the rotation is clockwise at carbon represented by R and anti-clockwise is S

7. Write the name of the molecule in alphabetic

Step 3: Naming of compound a

1. Parent cycloalkane is cyclohexane

2. Substituents are ethoxy and methyl groups

3. Position of ethoxy is1 and methyl is 3

4. If the rotation is clockwise at carbon represented by R like at C3 and anti-clockwise at C1. So, compound a has S configuration. 

5. So, IUPAC name is 1S,3R 1-ethoxy,3methyl cyclohexane

Step 4: Naming of compound b

1. Parent alkane is butane

2. Substituent are bromo phenyl and epoxy

3. Position of bromophenyl is at position 2 at ortho and epoxy is 2,

4. Here, molecule show trans relationship so prefix E is used

5. So, IUPAC name is E-2(o-bromo phenyl)2,3 ethoxy butane

Step 5: Naming of compound c

1. Parent thiol so ethane thiol

2. Substituent is cyclopentyl

3. Position of cyclopentyl is 1

4. If the rotation is anti-clockwise at C so, S- configuration

5. So, IUPAC name is S-1-cyclopential ethane thiol