Halogenated Hydrocarbons

Step 1: Understanding the Concept:
Chlorobenzene undergoes electrophilic substitution reactions. The Chlorine atom is ortho-para directing due to its +M effect (resonance effect).
Step 2: Detailed Explanation:
(i) Action of conc. (Nitration):
When chlorobenzene is heated with nitrating mixture (conc. conc. ), it forms a mixture of 1-chloro-2-nitrobenzene (minor) and 1-chloro-4-nitrobenzene (major).
Reaction:

(ii) Action of fuming (Sulfonation):
When chlorobenzene is heated with fuming sulfuric acid, it undergoes sulfonation to form 2-chlorobenzene sulfonic acid (minor) and 4-chlorobenzene sulfonic acid (major).
Reaction:
Step 3: Final Answer:
Nitration gives nitro derivatives, and sulfonation gives sulfonic acid derivatives, primarily at the para position.

Step 1: Understanding the Concept:
Enantiomers are a type of stereoisomers that occur in molecules containing a chiral center (a carbon atom bonded to four different groups).
Step 2: Detailed Explanation:
Enantiomers have identical physical properties like melting point, boiling point, and solubility, but they differ in two ways:
1. They rotate the plane of plane-polarized light in opposite directions (dextrorotatory and laevorotatory).
2. They react differently with other chiral reagents.
A classic example is d-lactic acid and l-lactic acid.
Step 3: Final Answer:
Enantiomers are optical isomers that are non-superimposable mirror images of each other.

Step 1: Understanding the Concept:
Alkaline hydrolysis of primary alkyl halides like bromomethane ( ) involves the attack of a hydroxide ion ( ) as a nucleophile.
Step 2: Detailed Explanation:
The reaction occurs in a single concerted step.
1. Backside Attack: The nucleophile ( ) attacks the carbon atom from the side opposite to the leaving group ( ).
2. Transition State: A pentacoordinate transition state is formed where the bond to is partially formed and the bond to is partially broken. The carbon is hybridized in this state.
3. Product Formation: The bond breaks completely, and the bond is fully established.
4. Inversion of Configuration: If the substrate were chiral, we would see "Walden Inversion", much like an umbrella turning inside out in a strong wind.
Rate Law: . It is a bimolecular, second-order reaction.
Step 3: Final Answer:
Alkaline hydrolysis of bromomethane is an reaction involving a single-step transition state and inversion of configuration.

Step 1: Understanding the Concept:
Acetonitrile is methyl cyanide ( ).
It contains two carbon atoms. The synthesis involves increasing the carbon chain length starting from an alkyl halide.
Step 2: Key Formula or Approach:
Reaction of alkyl halides with potassium cyanide ( ) yields alkyl cyanides (nitriles), whereas reaction with silver cyanide ( ) yields alkyl isocyanides.
Step 3: Detailed Explanation:
To obtain (2 carbons), we must start with an alkyl halide containing 1 carbon atom, which is methyl chloride ( ).
The reaction is:

If we used ethyl chloride ( ), the product would be propionitrile ( ).
If we used , the product would be methyl isocyanide ( ).
Step 4: Final Answer:
Acetonitrile is prepared by heating methyl chloride with alcoholic KCN.