Chemistry, Third edition

ALKANES 311

Example 17.2

Name the compound

CH 3 CHCH 2 CHCH 3
||
CH 3 CH 2
|
CH 2
|
CH 3

Answer

1.Identify the longest chain –

a heptane:

2.Identify the branches – there

are two methyl branches (dimethyl):

3.Number the carbon atoms:

a methyl on C 2 and one on C 4 :

Therefore, the name is 2,4-

dimethylheptane.

Writing structural formulae from names of alkanes

Write the structural formulae of:

(i) 3-methylpentane (iii)4-ethyl-2-methylheptane

(ii)2,2,5-trimethyloctane (iv)2,3,4-trimethylheptane.

Exercise 17E

——————

CH 3 CHCH 2 CH CH 3

| |

CH 3 CH 2

|

CH 2

|

CH 3

CH 3 CHCH 2 CHCH 3

|

CH 3

CH 2

|

CH 2

|

CH 3

123 4

CH 3 CHCH 2 CHCH 3

|

CH 3

CH 25

|

CH 26

|

CH 37

Naming alkanes

Name the following:

(i)iiCH 3 CHCH 3 (ii)CH 3 CH 2 CH 2 CHCH 2 CH 3

||

CH 3 CH 2

|

CH 2

|

CH 3

CH 3

|

CH 3 CH 3 CH 2

|||

(iii)CH 3 CCH 3 (iv)CH 3 CH 2 CH 2 CHCHCHCH 3

||

CH 3 CH 2

|

CH 3

Exercise 17D