Compounds undergoing Friedel-Crafts alkylation

In summary, Friedel-Crafts alkylation is a chemical reaction that involves the introduction of an alkyl group into an aromatic compound through the use of alkyl halides and a Lewis acid catalyst, such as aluminum chloride. This method enhances the reactivity of the aromatic ring, allowing for electrophilic substitution. However, the reaction can lead to polyalkylation and rearrangement of alkyl groups, which may result in undesired byproducts. The choice of alkyl halide, the presence of steric hindrance, and the reaction conditions significantly influence the efficiency and outcome of the alkylation process.
  • #1
jolly_math
51
5
Homework Statement
Which of the following compounds can undergo Friedel-Crafts alkylation?
Relevant Equations
Friedel-Crafts alkylation
1713022840300.png

The answer is that the 2nd, 3rd and 6th compounds can undergo Friedel-Crafts alkylation.

I don't understand why the 4th compound cannot undergo a Friedel-Crafts alkylation reaction, but the 2nd compound can. It has an activating NH2 group and a weakly deactivating Br group, and it's similar to the 2nd compound which has an activating CH3 group and a weakly deactivating Cl group – what makes it different?

Thank you.
 
Physics news on Phys.org
  • #2
What happens to the NH2 group in the presence of the Friedel-Crafts catalyst?
 
  • #3
jolly_math said:
Homework Statement: Which of the following compounds can undergo Friedel-Crafts alkylation?
Relevant Equations: Friedel-Crafts alkylation

View attachment 343324
The answer is that the 2nd, 3rd and 6th compounds can undergo Friedel-Crafts alkylation.

I don't understand why the 4th compound cannot undergo a Friedel-Crafts alkylation reaction, but the 2nd compound can. It has an activating NH2 group and a weakly deactivating Br group, and it's similar to the 2nd compound which has an activating CH3 group and a weakly deactivating Cl group – what makes it different?

Thank you.
The thing is the 4th compound has a NH2 group which has a lone pair but in presence of AlCl3 a strong electrophile , the NH2 gives up its lone pair and forms NH3+ cation which is a -M group and highly deactivating, but in the 2nd compound CH3 have activating nature and cannot give any electrons so the chlorine gets removed and CH3 gets added i think
 
  • #4
PhysicsEnjoyer31415 said:
The thing is the 4th compound has a NH2 group which has a lone pair but in presence of AlCl3 a strong electrophile , the NH2 gives up its lone pair and forms NH3+ cation which is a -M group and highly deactivating, but in the 2nd compound CH3 have activating nature and cannot give any electrons so the chlorine gets removed and CH3 gets added i think
Im sorry but to clarify , not the chlorine on the compound
 

FAQ: Compounds undergoing Friedel-Crafts alkylation

What is Friedel-Crafts alkylation?

Friedel-Crafts alkylation is an organic reaction that involves the introduction of an alkyl group into an aromatic ring. This reaction typically uses an alkyl halide and a Lewis acid catalyst, such as aluminum chloride, to facilitate the electrophilic substitution of the aromatic compound.

What are the limitations of Friedel-Crafts alkylation?

Some limitations of Friedel-Crafts alkylation include the possibility of polysubstitution, where multiple alkyl groups are added to the aromatic ring, leading to a mixture of products. Additionally, sterically hindered alkyl halides may not react efficiently, and the presence of electron-withdrawing groups on the aromatic ring can deactivate it, making it less reactive towards alkylation.

What types of compounds can undergo Friedel-Crafts alkylation?

Compounds that can undergo Friedel-Crafts alkylation include aromatic hydrocarbons, such as benzene and toluene, as well as other aromatic systems that possess electron-donating groups, which increase their reactivity. However, compounds with strong electron-withdrawing groups are less likely to participate in this reaction.

How does the choice of alkyl halide affect the reaction?

The choice of alkyl halide significantly influences the outcome of Friedel-Crafts alkylation. Primary alkyl halides generally yield better results due to less steric hindrance, while secondary and tertiary alkyl halides can lead to carbocation rearrangements, resulting in different products. Additionally, the stability of the carbocation intermediate formed during the reaction can impact the efficiency of alkylation.

What are some common applications of Friedel-Crafts alkylation?

Friedel-Crafts alkylation is widely used in organic synthesis to produce a variety of alkylated aromatic compounds, which are important intermediates in the manufacture of pharmaceuticals, agrochemicals, and polymers. This reaction is particularly valuable in the development of fragrances, dyes, and other fine chemicals.

Similar threads

What will be the product of this organic reaction?
Replies
28
Views
4K
Organic chemistry- adding amine group to benzene
Replies
3
Views
6K
Why Does C6H5CH(Cl)CH3 < (CH3)3 CCl < C6H5C(CH3)2 Cl Undergo SN1 Reaction?
Replies
1
Views
1K
Chemistry: Not a Friedel-Crafts Reaction
Replies
2
Views
2K
Identifying the Electrophile in But-2-ene and Bromine Reaction
Replies
5
Views
2K
Alkylation of Imines: achiral to chiral compounds
Replies
2
Views
2K
Exploring Alkyl Groups and their Role in Organic Chemistry
Replies
2
Views
12K
Organic Chemistry - Nomenclature Structures
Replies
2
Views
13K
Organic Chemistry: Sn1/E1/Sn2/E2/Alchol/Ether Transformations
Replies
4
Views
8K
Question Regarding Polar Protic Solvents
Replies
2
Views
7K

Hot Threads

Recent Insights

Back
Top