Halogen Derivatives - Class 12 MCQ

(i)

X :    Dehydrohalogenation    
Y:    Halogenation following anti-addition

Conceptual

reaction are governed by stability of carbocation, so, 3⁰ halides are more reactive

Boiling point is directly proportional to molecular masses.

Reactivity of alkyl halides for  reactions decreases with increase in steric hindrance i.e crowding or branching around B-carbon

CH₃ MgBr attacks on ketone in prefernce to esters & facilitates intramolecular S_N reaction.

Alkyl halides with Mg form Grignand reagent followed by intramolecular S_N reaction.

Reaction requires 4 moles of CH₃MgBr, two moles for nucleophilic substitution acid halide which results in the formation of ketones & rest two for ketone to 3⁰ alcohol.

Reaction is favoured by stability of carbcation

Stability of carbocation-decides rate of reaction (R) has 3⁰ halide but carbocation formed is unstable due angle strain.

Reaction follows  where elimination competes substitution, it shows inversion & retention product can not be  obtained.

Finkelstein reaction follows S_N2 reaction so, opposite product is formed

Formation of 2⁰ carbocation, followed by shift. 3⁰ alcohol is formed which an heating shows dehydration.

It is an example of William son’s synthesis, where 3⁰ halides give alkenes

Bicycle compounds has angle strain at bridge heat carbon, so it resists elimination as it  increases angle strain (d) involves opening of cyclic structure as it involves Hoffmann’s elimination.

reaction involves anti-elimination of halogens.

Formation of conjugated diene dominates as product is resonance stabilised

E₂ elimination require β-H an opposite orientation of halogen. 

reactions involve inversion of configuration,as given compound has ‘R’ configuration, so product will be ‘S’

(a) & (b)     involves F.C. acylation while (c) gives geminal diol after substitution.

E₂ involves simultaneous removal of H & halogen so, (b) is most suitable.

Dehalogenation involves anti-elimination so, meso compound gives Trans alkene
(a) is (2S,3R)-2,3-Dibromo butane

involves partial racemisation whileinvolves Walden inversion

Intramolecular substitution results in the formation five or six membered cyclic structure

Reaction follows mechanism

A is formed by Saytzeff’s rule while 
B is formed by Haffmann’s rule

Addition of hydrogen halides follows Markownikoff’s rule, so, 2⁰ & 3⁰ halides are formed. In (b) & (c) 3⁰ halides are                major product.