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Aryl halides are less reactive towards neucliophilic substitution reactions as compared to alkyl halides due to
  • a)
    Resonance stabilisation
  • b)
    Larger carbon–halogen bond
  • c)
    Formation of less stable carbonium ion
  • d)
    Inductive effect
Correct answer is option 'A'. Can you explain this answer?
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Aryl halides are less reactive towards neucliophilic substitution reac...
**Resonance Stabilization of Aryl Halides**

**Introduction**
Aryl halides (also known as aryl halogen compounds) are organic compounds that contain a halogen atom (such as chlorine, bromine, or iodine) attached to an aromatic ring. In comparison to alkyl halides, aryl halides are less reactive towards nucleophilic substitution reactions. The main reason behind this difference in reactivity is the resonance stabilization of aryl halides.

**Resonance Stabilization**
Resonance stabilization refers to the delocalization of electrons in a molecule or ion through the overlap of p-orbitals. In the case of aryl halides, the aromatic ring (such as benzene) possesses a system of conjugated π electrons. These π electrons are delocalized over the entire ring, leading to resonance stabilization.

**Resonance Structures**
In aryl halides, the resonance structures can be represented as follows:

![resonance structures](https://cdn1.edurev.in/edurevapi/image/eyJidWNrZXQiOiJlZHVyZXZpZXdzIiwia2V5Ijoic2NyZWVuc2NydWl0XzE1NjQ2MjkwNTI0MDYyNzkiLCJlbnN1cmUiOiJwcm90b2NvbCIsImVkaXRzIjp7InBvcyI6IjEzNiIsImNvbG9yIjoiIzAwMDAwMCJ9fQ)

**Resonance Stabilization Effect**
The resonance stabilization of aryl halides makes it difficult for a nucleophile to attack the electrophilic carbon atom attached to the halogen. This is because the electrons of the aromatic ring are already delocalized and contribute to the stability of the molecule. As a result, the electron density on the carbon atom is reduced, making it less susceptible to nucleophilic attack.

**Comparison with Alkyl Halides**
In contrast, alkyl halides do not possess a conjugated system of π electrons and, therefore, lack resonance stabilization. The electron density on the carbon atom in alkyl halides is higher, making them more prone to nucleophilic attack.

**Other Factors**
While resonance stabilization is the primary reason for the decreased reactivity of aryl halides towards nucleophilic substitution reactions, other factors such as the larger carbon-halogen bond length and the formation of less stable carbonium ions also contribute to their lower reactivity. However, these factors are not as significant as the resonance stabilization effect.

**Conclusion**
In conclusion, aryl halides are less reactive towards nucleophilic substitution reactions compared to alkyl halides due to their resonance stabilization effect. The delocalization of electrons in the conjugated π system of the aromatic ring reduces the electron density on the carbon atom, making it less susceptible to nucleophilic attack.
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Aryl halides are less reactive towards neucliophilic substitution reac...
Aryl halides are less reactive towards nucleophilic substitution reaction as compared to alkyl halides is because of resonance stabilization in aryl halide. Due to resonance, C−Cl bond becomes shorter and stronger and cannot be easily replaced by nucleophiles.
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Read the passage given below and answer the following questions:Nucleophilic substitution reaction of haloalkane can be conducted according to both SN1 and SN2 mechanisms. However, which mechanism it is based on is related to such factors as the structure of haloalkane, and properties of leaving group, nucleophilic reagent and solvent. Influences of halogen: No matter which mechanism the nucleophilic substitution reaction is based on, the leaving group always leave the central carbon atom with electron pair. This is just the opposite of the situation that nucleophilic reagent attacks the central carbon atom with electron pair. Therefore, the weaker the alkalinity of leaving group is , the more stable the anion formed is and it will be more easier for the leaving group to leave the central carbon atom; that is to say, the reactant is more easier to be substituted. The alkalinity order of halogen ion is I− < Br− < Cl− < F− and the order of their leaving tendency should be I− > Br− > Cl− > F−. Therefore, in four halides with the same alkyl and different halogens, the order of substitution reaction rate is RI > RBr > RCl > RF. In addition, if the leaving group is very easy to leave, many carbocation intermediates are generated in the reaction and the reaction is based on SN1 mechanism. If the leaving group is not easy to leave, the reaction is based on SN2 mechanism. Influences of solvent polarity: In SN1 reaction, the polarity of the system increases from the reactant to the transition state, because polar solvent has a greater stabilizing effect on the transition state than the reactant, thereby reduce activation energy and accelerate the reaction. In SN2 reaction, the polarity of the system generally does not change from the reactant to the transition state and only charge dispersion occurs. At this time, polar solvent has a great stabilizing effect on Nu than the transition state, thereby increasing activation energy and slow down the reaction rate. For example, the decomposition rate (SN1) of tertiary chlorobutane in 25° water (dielectric constant 79) is 300000 times faster than in ethanol (dielectric constant 24). The reaction rate (SN2) of 2-bromopropane and NaOH in ethanol containing 40% water is twice slower than in absolute ethanol. In a word, the level of solvent polarity has influence on both SN1 and SN2 reactions, but with different results. Generally speaking, weak polar solvent is favorable for SN2 reaction, while strong polar solvent is favorable for SN1 reaction, because only under the action of polar solvent can halogenated hydrocarbon dissociate into carbocation and halogen ion and solvents with a strong polarity is favorable for solvation of carbocation, increasing its stability. Generally speaking, the substitution reaction of tertiary haloalkane is based on SN1 mechanism in solvents with a strong polarity (for example, ethanol containing water).Q. Nucleophilic substitution will be fastest in case of

Read the passage given below and answer the following questions:Nucleophilic substitution reaction of haloalkane can be conducted according to both SN1 and SN2 mechanisms. However, which mechanism it is based on is related to such factors as the structure of haloalkane, and properties of leaving group, nucleophilic reagent and solvent. Influences of halogen: No matter which mechanism the nucleophilic substitution reaction is based on, the leaving group always leave the central carbon atom with electron pair. This is just the opposite of the situation that nucleophilic reagent attacks the central carbon atom with electron pair. Therefore, the weaker the alkalinity of leaving group is , the more stable the anion formed is and it will be more easier for the leaving group to leave the central carbon atom; that is to say, the reactant is more easier to be substituted. The alkalinity order of halogen ion is I− < Br− < Cl− < F− and the order of their leaving tendency should be I− > Br− > Cl− > F−. Therefore, in four halides with the same alkyl and different halogens, the order of substitution reaction rate is RI > RBr > RCl > RF. In addition, if the leaving group is very easy to leave, many carbocation intermediates are generated in the reaction and the reaction is based on SN1 mechanism. If the leaving group is not easy to leave, the reaction is based on SN2 mechanism. Influences of solvent polarity: In SN1 reaction, the polarity of the system increases from the reactant to the transition state, because polar solvent has a greater stabilizing effect on the transition state than the reactant, thereby reduce activation energy and accelerate the reaction. In SN2 reaction, the polarity of the system generally does not change from the reactant to the transition state and only charge dispersion occurs. At this time, polar solvent has a great stabilizing effect on Nu than the transition state, thereby increasing activation energy and slow down the reaction rate. For example, the decomposition rate (SN1) of tertiary chlorobutane in 25° water (dielectric constant 79) is 300000 times faster than in ethanol (dielectric constant 24). The reaction rate (SN2) of 2-bromopropane and NaOH in ethanol containing 40% water is twice slower than in absolute ethanol. In a word, the level of solvent polarity has influence on both SN1 and SN2 reactions, but with different results. Generally speaking, weak polar solvent is favorable for SN2 reaction, while strong polar solvent is favorable for SN1 reaction, because only under the action of polar solvent can halogenated hydrocarbon dissociate into carbocation and halogen ion and solvents with a strong polarity is favorable for solvation of carbocation, increasing its stability. Generally speaking, the substitution reaction of tertiary haloalkane is based on SN1 mechanism in solvents with a strong polarity (for example, ethanol containing water).Q. SN1 reaction will be fastest in case of

Read the passage given below and answer the following questions:Nucleophilic substitution reaction of haloalkane can be conducted according to both SN1 and SN2 mechanisms. However, which mechanism it is based on is related to such factors as the structure of haloalkane, and properties of leaving group, nucleophilic reagent and solvent. Influences of halogen: No matter which mechanism the nucleophilic substitution reaction is based on, the leaving group always leave the central carbon atom with electron pair. This is just the opposite of the situation that nucleophilic reagent attacks the central carbon atom with electron pair. Therefore, the weaker the alkalinity of leaving group is , the more stable the anion formed is and it will be more easier for the leaving group to leave the central carbon atom; that is to say, the reactant is more easier to be substituted. The alkalinity order of halogen ion is I− < Br− < Cl− < F− and the order of their leaving tendency should be I− > Br− > Cl− > F−. Therefore, in four halides with the same alkyl and different halogens, the order of substitution reaction rate is RI > RBr > RCl > RF. In addition, if the leaving group is very easy to leave, many carbocation intermediates are generated in the reaction and the reaction is based on SN1 mechanism. If the leaving group is not easy to leave, the reaction is based on SN2 mechanism. Influences of solvent polarity: In SN1 reaction, the polarity of the system increases from the reactant to the transition state, because polar solvent has a greater stabilizing effect on the transition state than the reactant, thereby reduce activation energy and accelerate the reaction. In SN2 reaction, the polarity of the system generally does not change from the reactant to the transition state and only charge dispersion occurs. At this time, polar solvent has a great stabilizing effect on Nu than the transition state, thereby increasing activation energy and slow down the reaction rate. For example, the decomposition rate (SN1) of tertiary chlorobutane in 25° water (dielectric constant 79) is 300000 times faster than in ethanol (dielectric constant 24). The reaction rate (SN2) of 2-bromopropane and NaOH in ethanol containing 40% water is twice slower than in absolute ethanol. In a word, the level of solvent polarity has influence on both SN1 and SN2 reactions, but with different results. Generally speaking, weak polar solvent is favorable for SN2 reaction, while strong polar solvent is favorable for SN1 reaction, because only under the action of polar solvent can halogenated hydrocarbon dissociate into carbocation and halogen ion and solvents with a strong polarity is favorable for solvation of carbocation, increasing its stability. Generally speaking, the substitution reaction of tertiary haloalkane is based on SN1 mechanism in solvents with a strong polarity (for example, ethanol containing water).Q. SN1 reaction will be fastest in which of the following solvents?

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Aryl halides are less reactive towards neucliophilic substitution reactions as compared to alkyl halides due toa)Resonance stabilisationb) Larger carbon–halogen bondc)Formation of less stable carbonium iond)Inductive effectCorrect answer is option 'A'. Can you explain this answer?
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Aryl halides are less reactive towards neucliophilic substitution reactions as compared to alkyl halides due toa)Resonance stabilisationb) Larger carbon–halogen bondc)Formation of less stable carbonium iond)Inductive effectCorrect answer is option 'A'. Can you explain this answer? for NEET 2024 is part of NEET preparation. The Question and answers have been prepared according to the NEET exam syllabus. Information about Aryl halides are less reactive towards neucliophilic substitution reactions as compared to alkyl halides due toa)Resonance stabilisationb) Larger carbon–halogen bondc)Formation of less stable carbonium iond)Inductive effectCorrect answer is option 'A'. Can you explain this answer? covers all topics & solutions for NEET 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for Aryl halides are less reactive towards neucliophilic substitution reactions as compared to alkyl halides due toa)Resonance stabilisationb) Larger carbon–halogen bondc)Formation of less stable carbonium iond)Inductive effectCorrect answer is option 'A'. Can you explain this answer?.
Solutions for Aryl halides are less reactive towards neucliophilic substitution reactions as compared to alkyl halides due toa)Resonance stabilisationb) Larger carbon–halogen bondc)Formation of less stable carbonium iond)Inductive effectCorrect answer is option 'A'. Can you explain this answer? in English & in Hindi are available as part of our courses for NEET. Download more important topics, notes, lectures and mock test series for NEET Exam by signing up for free.
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