NEET Chemistry Reaction Mechanism - Organic Chemistry Questions Solved


Reactivity order of halides for dehydrohalogenation is 

(a) R-F>R-Cl>R-Br>R-I(b) R-I>R-Br>R-Cl>R-F(c) R-I>R-Cl>R-Br>R-F(d) R-F>R-I>R-Br>R-Cl

Concept Videos :-

#6 | Elimination Reaction: Part 2

Concept Questions :-

Hofmann's Elimination & Saytzeff Elimination

(b) F,Cl,Br and I are the elements of VII A group. In a group atomic radii increases from top to bottom and the bond dissociation energy decreases as

      R-F>R-Cl>R-Br>R-I

So, during dehydrohalogenation R-I bond breaks more easily than R-I bond. Hence, order of reactivity will be

       R-I>R-Br>R-Cl>R-F

Difficulty Level:

  • 29%
  • 56%
  • 13%
  • 3%
Crack NEET with Online Course - Free Trial (Offer Valid Till September 19, 2019)

The increasing order of hydrolysis of the following compounds:

(a) (i)<(iii)<(ii)

(b) (ii)<(iii)<(i)

(c) (ii)<(i)<(iii)

(d) (i)<(ii)<(iii)

Concept Videos :-

#5 | Elimination Reaction: Part 1
#7 | Elimination Reaction: Part 3

Concept Questions :-

Free Radical /Reaction intermediate

(a) Higher is the stability of intermediate (carbocation), more is the reactivity of compound.

(ii) forms allyl carbocation, (iii) forms secondary  carbocation and (i) forms phenyl carbocation.

Difficulty Level:

  • 29%
  • 22%
  • 11%
  • 41%
Crack NEET with Online Course - Free Trial (Offer Valid Till September 19, 2019)

What is major product of following reaction ?

(3) Dehydrohalogenation is an example of anti elimination.

 

 

Dehydrohalogenation: A reaction in which a hydrogen atom and a halogen atom are removed from adjacent atoms in a molecule, forming (usually) an alkene or an alkyne.

 


When reacted with strong base such as hydroxide ioncyclohexyl chloride suffers dehydrohalogenation by a concerted E2 reaction mechanism (shown here). The atoms which comprise the moleculeof HCl lost are shown in red. This reaction is the conceptual reverse of electrophilic addition of HCl to cyclohexene.


tertiary alkyl halide such as 2-iodo-2-methylpropane can undergo dehydrohalogenation by the E1 reaction mechanism (shown here). The atoms which comprise the molecule of HI lost are shown in red.


When reacted with a strong base such as sodium amide (NaNH2), a geminal dibromide can undergo a double dehydrohalogenation reaction to give an alkyne. The reaction involves a pair of consecutive E2 elimination steps.
  •  

Difficulty Level:

  • 21%
  • 46%
  • 29%
  • 6%
Crack NEET with Online Course - Free Trial (Offer Valid Till September 19, 2019)

Concept Videos :-

#5 | Elimination Reaction: Part 1
#7 | Elimination Reaction: Part 3

Concept Questions :-

Free Radical /Reaction intermediate

Difficulty Level:

  • 21%
  • 31%
  • 28%
  • 21%
Crack NEET with Online Course - Free Trial (Offer Valid Till September 19, 2019)

Consider the given reaction below:

Which of these is true regarding the reaction shown above?

(1) the configuration of the chiral carbon remains same.

(2) the configuration of the chiral carbon gets inverted

(3) the  compound formed as a product must be a dextro isomer

(4) the reactant is optically inactive but the product is obtained as a levo isomer.

Concept Videos :-

#9 | SN1 & SN2 Reactions: 1
#10 | SN1 & SN2 Reactions: 2

Concept Questions :-

SN1 & SN2 Reactions

(1) the configuration of the chiral carbon remains same because the priority of CN- and -COOH is same.

Difficulty Level:

  • 57%
  • 17%
  • 16%
  • 11%
Crack NEET with Online Course - Free Trial (Offer Valid Till September 19, 2019)

Zn ANH3/EtOHNa B

Product 2 is

(1)

Difficulty Level:

  • 30%
  • 27%
  • 36%
  • 9%
Crack NEET with Online Course - Free Trial (Offer Valid Till September 19, 2019)

The ease of dehydrohalogen of alkyl halide with alcoholic KOH is(1) 3°>2°>1°(2) 3°<2°<1°(3) 3°>2°<1°(4) 3°<2°>1°

(1) the ease of dehydrohalogenation of alkyl halide is: 3°>2°>1°

Difficulty Level:

  • 71%
  • 21%
  • 7%
  • 4%
Crack NEET with Online Course - Free Trial (Offer Valid Till September 19, 2019)

Which of the following is formed by the thermal decomposition of the hydroxide of:

It is an example of Hoffman elimination

 

 

 

 

 

Difficulty Level:

  • 26%
  • 35%
  • 21%
  • 20%
Crack NEET with Online Course - Free Trial (Offer Valid Till September 19, 2019)

Read the following road map carefully

(1) Both the ethers obtained by the two routes have opposite but equal optical rotation.

(2) One of the ether is obtained as a racemic mixture.

(3) Step II & III both are SN2 reaction and both have inversion.

(4) Step II has inversion but step III has retention.

Concept Videos :-

#9 | SN1 & SN2 Reactions: 1
#10 | SN1 & SN2 Reactions: 2

Concept Questions :-

SN1 & SN2 Reactions

(1)

Difficulty Level:

  • 31%
  • 29%
  • 31%
  • 10%
Crack NEET with Online Course - Free Trial (Offer Valid Till September 19, 2019)

PhOH NaOHMe2SO4 P, P is

(1) Ph–O–SO2OMe

(2) PhOMe

(3) PhOSO2OPh

(4) PhMe

Concept Videos :-

#11 | Substitution Reactions in Alcohols: 1
#12 | Substitution Reactions in Alcohols: 2

Concept Questions :-

(2)

Difficulty Level:

  • 32%
  • 50%
  • 11%
  • 8%
Crack NEET with Online Course - Free Trial (Offer Valid Till September 19, 2019)