Question

How many of the following names are correct? Correct the incorrect names.

a. 3-pentene

b. 2-octene

c. 2-vinylpentane

d. 1-ethyl-1-pentene

e. 5-ethylcyclohexene

f. 5-chloro-3-hexene

g. 2-ethyl-2-butene

h. (E)-2-methyl-1-hexene

i. 2-methylcyclopentene

Short answer

Here only b) name is correct i.e. 2-octene

a) 2-pentene

b) 2-octene

c) 3-methyl-1-hexene

d) 3-heptene

e) 4-ethylcyclohexene

f) 2-chloro-3-hexene

g) 3-methyl-2-pentene

h) 2-methyl-1-hexene

i) 1-methylcyclopentene

Step-by-step solution

How to do naming of these compounds:

This naming is done according to IUPAC nomenclature:

1. Select longest parent chain.

2. Functional group has to be given lowest number.

3. If two Functional groups are present then give number according to priority order.

Step 2:Final answer

a) Double bond has to be given lowest number so the name is 2-pentene

b) This name is correct.

c) Longest chain has to choose and then give double bond a lowest numberso the name is 3-methyl-1-hexene.

d) Longest chain has to choose then give double bond a lowest number so the name is 3-heptene

e) Double bond has to give number 1 then give the substituent a lowest number so the name is 4-ethylcyclohexene.

f) Chlorine group has a lowest number so the name is 2-chloro-3-hexene.

g) Longest chain has to choose and then give double bond a lowest number then give number to the substituentso the name is 3-methyl-2-pentene.

h) Substituent has a lowest number so the name is 1-methylcyclopentene.