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Alkyl halides undergo nucleophilic subst...

Alkyl halides undergo nucleophilic substitution reactions in which halogen atom is replaced by other atom.
`RX + Nu:^(-) to Nu-R + X^(-)`
These reactions follow `S_(N)1` and `S_(N)2` type mechanism, in which `S_(N)1` takes place in two steps while `S_(N)2` takes place in single step. Due to their tendency to undergo substitution by a large number of nucleophiles, they form a variety of products.
Which of the following is least reactive towards `S_(N)2` mechanism ?

A

`(CH_(3))_(2)CHCH_(2)Br`

B

`(CH_(3))_(3)C Br`

C

`CH_(3)CH_(2)Br`

D

`(CH_(3))_(2)CHBr`

Text Solution

AI Generated Solution

The correct Answer is:
To determine which alkyl halide is least reactive towards the \( S_N2 \) mechanism, we need to understand the characteristics of \( S_N2 \) reactions and the impact of steric hindrance on reactivity. ### Step-by-Step Solution: 1. **Understanding \( S_N2 \) Mechanism:** - The \( S_N2 \) (bimolecular nucleophilic substitution) mechanism involves a single concerted step where the nucleophile attacks the carbon atom from the opposite side of the leaving group (halogen). This results in the formation of a transition state where both the nucleophile and the leaving group are partially bonded to the carbon. 2. **Steric Hindrance:** - The reactivity of alkyl halides in \( S_N2 \) reactions is significantly influenced by steric hindrance. The more sterically hindered the carbon atom is, the less reactive it will be towards nucleophilic attack. - Tertiary (3°) alkyl halides have the highest steric hindrance, followed by secondary (2°), and then primary (1°) alkyl halides, which have the least steric hindrance. 3. **Identifying the Alkyl Halides:** - Let's consider the types of alkyl halides that might be present in the options: - 1° Alkyl Halide (least steric hindrance) - 2° Alkyl Halide (moderate steric hindrance) - 3° Alkyl Halide (most steric hindrance) 4. **Comparing Reactivity:** - Since \( S_N2 \) reactions are favored by less steric hindrance, the 3° alkyl halide will be the least reactive towards the \( S_N2 \) mechanism due to the significant steric hindrance around the carbon atom. 5. **Conclusion:** - Therefore, the alkyl halide that is least reactive towards the \( S_N2 \) mechanism is the tertiary alkyl halide. ### Final Answer: The tertiary alkyl halide (3°) is the least reactive towards the \( S_N2 \) mechanism. ---
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Alkyl halides undergo nucleophilic substitution reactions in which halogen atom is replaced by other atom. RX + Nu:^(-) to Nu-R + X^(-) These reactions follow S_(N)1 and S_(N)2 type mechanism, in which S_(N)1 takes place in two steps while S_(N)2 takes place in single step. Due to their tendency to undergo substitution by a large number of nucleophiles, they form a variety of products. In which of the following pairs, the first nucleophile is stronger?

Alkyl halides undergo nucleophilic substitution reactions in which halogen atom is replaced by other atom. RX + Nu:^(-) to Nu-R + X^(-) These reactions follow S_(N)1 and S_(N)2 type mechanism, in which S_(N)1 takes place in two steps while S_(N)2 takes place in single step. Due to their tendency to undergo substitution by a large number of nucleophiles, they form a variety of products. In which of the following pairs, the first compound is better S_(N)2 substrate ?

Knowledge Check

  • Alkyl halides undergo nucleophilic substitution reactions in which halogen atom is replaced by other atom. RX + Nu:^(-) to Nu-R + X^(-) These reactions follow S_(N)1 and S_(N)2 type mechanism, in which S_(N)1 takes place in two steps while S_(N)2 takes place in single step. Due to their tendency to undergo substitution by a large number of nucleophiles, they form a variety of products. Which of the following has highest nucleophilicity?

    A
    `SH^(-)`
    B
    `H_(2)O`
    C
    `OH^(-)`
    D
    `F^(-)`

  • Alkyl halides undergo nucleophilic substitution reactions in which halogen atom is replaced by other atom. RX + Nu:^(-) to Nu-R + X^(-) These reactions follow S_(N)1 and S_(N)2 type mechanism, in which S_(N)1 takes place in two steps while S_(N)2 takes place in single step. Due to their tendency to undergo substitution by a large number of nucleophiles, they form a variety of products. Which of the following has highest nucleophilicity?

    A
    `SH^(-)`
    B
    `H_(2)O`
    C
    `OH^(-)`
    D
    `F^(-)`

  • Alkyl halides undergo nucleophilic substitution reactions in which halogen atom is replaced by other atom. RX + Nu:^(-) to Nu-R + X^(-) These reactions follow S_(N)1 and S_(N)2 type mechanism, in which S_(N)1 takes place in two steps while S_(N)2 takes place in single step. Due to their tendency to undergo substitution by a large number of nucleophiles, they form a variety of products. In which of the following pairs, the first nucleophile is stronger?

    A
    `Cl^(-), I^(-)`
    B
    `CH_(3)OH, CH_(3)S^(-)`
    C
    `(CH_(3)CH_(2))_(2)NH, (CH_(3)CH_(2))_(3)N`
    D
    `(CH_(3))_(2)O, (CH_(3))_(3)N`

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    Alkyl halides undergo nucleophilic substitution reactions in which halogen atom is replaced by other atom. RX + Nu:^(-) to Nu-R + X^(-) These reactions follow S_(N)1 and S_(N)2 type mechanism, in which S_(N)1 takes place in two steps while S_(N)2 takes place in single step. Due to their tendency to undergo substitution by a large number of nucleophiles, they form a variety of products. In which of the following pairs, the first compound is better S_(N)2 substrate ?

    Alkyl halides undergo nucleophilic substitution reactions in which halogen atom is replaced by other atom. RX + Nu:^(-) to Nu-R + X^(-) These reactions follow S_(N)1 and S_(N)2 type mechanism, in which S_(N)1 takes place in two steps while S_(N)2 takes place in single step. Due to their tendency to undergo substitution by a large number of nucleophiles, they form a variety of products. In which of the following nucleophilic substitution reaction, the product formed is racemic mixture ?

    Alkyl halides undergo nucleophilic substitution reactions in which halogen atom is replaced by other atom. RX + Nu:^(-) to Nu-R + X^(-) These reactions follow S_(N)1 and S_(N)2 type mechanism, in which S_(N)1 takes place in two steps while S_(N)2 takes place in single step. Due to their tendency to undergo substitution by a large number of nucleophiles, they form a variety of products. In which of the following nucleophilic substitution reaction, the product formed is racemic mixture ?

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