Question

What would be the structure of 4 - chloropentan - 2 - one?

Answer 1

Hint: As we know that nomenclature involves two systems for naming of the organic compounds and these are trivial systems and IUPAC systems. IUPAC system consists of a root or base, primary and secondary prefix and suffix and any substituent for naming a compound.

Complete step by step solution:
As we have learnt that IUPAC is the short for International Union of Pure and Applied Chemistry. It provides some rules for naming of the organic compounds. Using these rules we can write a unique name for any distinct compound and likewise we can make the structure from the given IUPAC name. IUPAC system consists of three main features which are: a root representing the chain of carbon atoms in molecular structure, presence of primary prefix, secondary prefix, primary suffix and secondary suffix and lastly the name of the substituents completing the molecular structure or formula.
Let us try and draw the correct structure of \[4 - chloropentan - 2 - one\]. We will go step by step as shown below:-
Step 1:- First we will find out the root word from the name given above, we can see that the root word is “pent” in the compound which means it has the longest chain of five carbon atoms.
              $\mathop C\limits^5 - \mathop C\limits^4 - \mathop C\limits^3 - \mathop C\limits^2 - \mathop C\limits^1 $
Step 2:- Next we will find out any functional group attached, and we can see that there is one functional group attached that is chloro and it is numbered as $4$, hence we can make that it is attached on the fourth carbon atom.

Step 3:- Next we will find out any ketone group attached, and yes there is one ketone group attached and it is numbered $2$, hence we can make that it is attached on the second carbon atom.

Lastly we can attach the remaining hydrogen atoms on the carbons. Therefore from the above steps we can say that the chemical formula for the \[4 - chloropentan - 2 - one\] is \[{C_5}{H_9}ClO\]. And its chemical structure is shown below as:

Note: Always remember that the parent chain will start from the side of attachment of the functional group. Also remember the order of preference of functional groups, direction of the numbering of carbon atoms and placing the halogen and ketone groups to their respective place and the bonding between carbon and oxygen as well as carbon and other atoms.