Answer
The following are the structure or name of each compound:
Work Step by Step
Question a:
Step 1: Count the no. of C in a straight chain. Here, the no. of C in straight chain is 5. So, main prefix is ‘pent’.
Step 2: Identify the functional group and its position. Here, the functional group present is ketone and hence, the ending name will be ‘anone’. Now, to get the position of the functional group we have to numbering the C atom in straight chain so that the C associated with functional group gets the minimum number. Here, numbering will be done from right side so the C associated with functional group gets the number ‘2’. 2 is added before main prefix ‘pent’. So, the complete name of the compound is 2-pentanone.
Question b:
Step 1: main prefix is ‘pent’. So, no. of C = 5. Draw 5 no. of C in a straight line and numbering 1 to 5 from left to right.
Step 2: ending name here is ‘anone’. So, a ketone functional group is present here at 3 no. C (as the name suggests 3-pentanone). Add the functional group on no. 3 Carbon.
Step 3: The remaining valency of C is filled with H.
Question c:
Step 1: main prefix is ‘prop’. So, no. of C = 3. Draw 3 C in a straight line and join them with single bond and numbering from right to left.
Step 2: ending name is ‘anal’. So, an aldehyde group is present here and it will always be on no. 1 Carbon. Add the functional group on no. 1 Carbon.
Step 3: The remaining valency of C is filled with H.
Question d:
Step 1: Count the no. of C. Here, no. of C in straight chain = 7. So, main prefix is ‘hept’.
Step 2: Identify the functional group. Here, it is Aldehyde. So, the ending name will be ‘anal’ and Aldehyde group is always be at no. 1 position if we numbering the C in straight chain. So, no need to mention the number while naming the aldehyde.
