Q.Write structural formulae for compounds named as—

The key idea is IUPAC Nomenclature and Structural Representation. Drawing structural formulae from IUPAC names requires identifying the parent chain, functional groups, and substituents along with their positions.

(a) For 1-Bromoheptane:

1. The parent chain "heptane" indicates a 7-carbon alkane.
2. "1-Bromo" means a bromine atom is attached to the first carbon of the chain.
3. The structural formula is $\text{BrCH}_2\text{CH}_2\text{CH}_2\text{CH}_2\text{CH}_2\text{CH}_2\text{CH}_3$.

(b) For 5-Bromoheptanoic acid:

1. The parent chain "heptanoic acid" indicates a 7-carbon chain with a carboxylic acid group ($-\text{COOH}$) at carbon 1.
2. "5-Bromo" means a bromine atom is attached to the fifth carbon, counting from the carboxylic acid carbon. …

When drawing the structural formula of an organic compound from its IUPAC name, we essentially reverse the naming process. The name provides all the necessary information: the length and type of the main carbon chain, the primary functional group, and the identity and position of any substituents.

The general strategy is to first identify the parent chain and its primary functional group, then number the chain, and finally attach the substituents at their indicated positions.

(a) 1-Bromoheptane

1. Identify the parent chain: The suffix "-ane" indicates an alkane, and "hept-" signifies a 7-carbon chain. So, the parent chain is a 7-carbon saturated hydrocarbon.

   $\text{C}-\text{C}-\text{C}-\text{C}-\text{C}-\text{C}-\text{C}$

2. Identify the substituent and its position: "1-Bromo" means a bromine atom ($\text{Br}$) is attached to the first carbon atom of the parent chain.

   $\text{Br}-\text{C}-\text{C}-\text{C}-\text{C}-\text{C}-\text{C}-\text{C}$

3. Complete the valencies with hydrogen atoms: Each carbon atom must form four bonds. Add hydrogen atoms to satisfy the valency of each carbon.

   • The first carbon (C1) is bonded to $\text{Br}$ and one other carbon, so it needs two hydrogen atoms ($\text{CH}_2\text{Br}$).
   • Carbons 2 through 6 are each bonded to two other carbons, so they each need two hydrogen atoms ($\text{CH}_2$).
   • The last carbon (C7) is bonded to only one other carbon, so it needs three hydrogen atoms ($\text{CH}_3$).

   Combining these, the structural formula is:

   $\text{CH}_3\text{CH}_2\text{CH}_2\text{CH}_2\text{CH}_2\text{CH}_2\text{CH}_2\text{Br}$

(b) 5-Bromoheptanoic acid

1. Identify the parent chain and primary functional group: The suffix "-oic acid" indicates a carboxylic acid functional group ($-\text{COOH}$). "Heptan-" signifies a 7-carbon chain. In carboxylic acids, the carbon atom of the $-\text{COOH}$ group is always designated as carbon number 1.

   So, we have a 7-carbon chain with a $-\text{COOH}$ group at one end (C1).

   $\text{C}\text{OOH}-\text{C}-\text{C}-\text{C}-\text{C}-\text{C}-\text{C}$

2. Identify the substituent and its position: "5-Bromo" means a bromine atom ($\text{Br}$) is attached to the fifth carbon atom of the parent chain, counting from the carboxylic acid carbon (C1).

   Let's number the chain from the $-\text{COOH}$ end: …