Organic Chemistry

Step 1: Understanding the Concept:
Iodoform test is given by compounds having or group.
Step 2: Detailed Explanation:
Acetone contains the group and gives positive iodoform test.
Step 3: Final Answer:
Acetone gives positive iodoform test.

Step 1: Understanding the Concept:
proceeds via a carbocation intermediate.
Step 2: Detailed Explanation:
In reactions, the carbocation intermediate is planar, leading to attack from both sides, resulting in both inversion and retention, hence racemization.
Step 3: Final Answer:
Racemization occurs due to both inversion and retention.

Step 1: Understanding the Concept:
Phenol undergoes electrophilic substitution at ortho and para positions.
Step 2: Detailed Explanation:
Phenol reacts with excess bromine water to give 2,4,6-tribromophenol (white precipitate).
Step 3: Final Answer:
The product is 2,4,6-tribromophenol.

Step 1: Understanding the Concept:
Ammonium salts of carboxylic acids on heating give amides.
Step 2: Detailed Explanation:
(X). On heating, (Y = acetamide).
Step 3: Final Answer:
Y is .

Step 1: Understanding the Concept:
acts as a Lewis acid in Friedel-Crafts reactions.
Step 2: Detailed Explanation:
acts as a Lewis acid and generates the electrophile ( or ) in Friedel-Crafts reactions.
Step 3: Final Answer:
produces the electrophile.

Step 1: Understanding the Concept:
Stereoisomers include both geometrical and optical isomers.
Step 2: Detailed Explanation:
Pent-3-en-2-ol has one chiral carbon and one double bond showing geometrical isomerism, giving total 4 stereoisomers.
Step 3: Final Answer:
There are 4 stereoisomers.

Step 1: Understanding the Concept:
Reimer-Tiemann reaction is used to introduce -CHO group on phenol.
Step 2: Detailed Explanation:
Reimer-Tiemann reaction involves dichlorocarbene ( ) as an intermediate.
Step 3: Final Answer:
The intermediate is carbene.

Step 1: Understanding the Concept:
Aldol condensation requires -hydrogen atoms.
Step 2: Detailed Explanation:
Chloral ( ) has no -hydrogen atom, so it does not undergo aldol condensation.
Step 3: Final Answer:
Chloral does not undergo aldol condensation.

Step 1: Understanding the Concept:
is favoured by stable carbocation intermediates.
Step 2: Detailed Explanation:
Bulky groups stabilize the carbocation intermediate and hinder attack, thus favouring .
Step 3: Final Answer:
is favoured by bulky groups.

Step 1: Understanding the Concept:
Hydrogenation of an alkene removes the double bond but preserves chirality if present.
Step 2: Detailed Explanation:
3-methyl-1-pentene is optically active due to chiral carbon. Hydrogenation gives 3-methylpentane which is optically inactive.
Step 3: Final Answer:
3-methyl-1-pentene is the correct answer.