Alcohols Phenols And Ethers

Step 1: Identifying the Functional Group and Parent Chain
- The given structure consists of a benzene ring attached to an alkoxy (-O-R) group.
- The longest alkyl chain attached to the oxygen atom is pentane (C H ), making it a pentoxy (-O-C H ) derivative.
Step 2: Identifying Substituents and Their Positions
- A methyl (-CH ) group is present on the fourth carbon of the pentoxy chain.
- The oxygen is directly attached to the benzene ring, making it an alkoxybenzene.
Step 3: Naming the Compound
- The correct IUPAC name follows the alkoxybenzene convention, with the longest chain numbered from the oxygen atom.
- Since the methyl group is at the 4th position, the correct name is 4-Methyl pentoxybenzene.
Step 4: Evaluating the Given Options
- Option (1): Incorrect, as the methyl group is at position 4, not 2.
- Option (2): Correct, as 4-Methyl pentoxybenzene is the correct name.
- Option (3): Incorrect, as the functional group should be named as "alkoxybenzene," not "phenoxyalkane."
- Option (4): Incorrect, as the methyl group is at position 4, not 2.
Thus, the correct answer is

Option (2).

Step 1: Understanding the Reaction Type
- The reaction involves the conversion of an alcohol to an alkyl iodide.
- The preferred method for this transformation is using potassium iodide ( ) in the presence of a strong acid.
Step 2: Choosing the Suitable Acidic Medium
1. Use of (Sulfuric Acid):
- Sulfuric acid oxidizes iodide ions ( ) to molecular iodine ( ), reducing the availability of needed for substitution.
- This results in a poor yield.
2. Use of (Phosphoric Acid, 95\% concentration):
- Unlike sulfuric acid, phosphoric acid does not oxidize , leading to a better yield of alkyl iodide.
- The reaction mechanism involves protonation of the hydroxyl group, making it a better leaving group, followed by nucleophilic substitution by .
Step 3: Evaluating the Given Options
- Option (1): Incorrect, as sulfuric acid leads to poor yield due to oxidation of .
- Option (2): Correct, as provides the best yield of alkyl iodide.
- Option (3): Incorrect, as sodium iodide ( ) with zinc chloride ( ) is used for Lucas test, not for alkyl iodide preparation.
- Option (4): Incorrect, as pure hydriodic acid ( ) is not typically used due to instability and side reactions.
Thus, the correct answer is

Option (2).

Step 1: Understanding Bond Angles in Alcohols and Ethers
- Structure A: Methanol ( )
- The central oxygen atom in methanol is sp hybridized with a bent geometry.
- Due to the presence of lone pairs on oxygen, the actual bond angle is slightly greater than the tetrahedral angle .
- This increase is due to repulsion between the lone pairs and bond pairs.
- Structure B: Dimethyl Ether ( )
- Oxygen is sp hybridized and forms two sigma bonds with carbon.
- The bond angle in ethers is approximately due to similar electron pair repulsions.
Step 2: Evaluating the Given Options
- Option (1): Incorrect, as should be equal to , not greater.
- Option (2): Incorrect, as alcohols generally have bond angles slightly greater than .
- Option (3): Correct, as (methanol) and (ether).
- Option (4): Incorrect, as it misplaces the bond angle conditions.
Thus, the correct answer is

Option (3).