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The correct statement concerning a SN2 reaction is
  • a)
    the reaction mechanism involve atleast one reactive intermediate
  • b)
    transition state is pentavalent
  • c)
    product is formed after passing through several transition states
  • d)
    nucleophile attacks from front side on which leaving group is present
Correct answer is option 'B'. Can you explain this answer?
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The correct statement concerning a SN2 reaction isa)the reaction mecha...
The transition state in SN2 reaction is pentavalent as indicated here.
 
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The correct statement concerning a SN2 reaction isa)the reaction mecha...
The Correct Statement Concerning a SN2 Reaction

The correct statement concerning a SN2 (substitution nucleophilic bimolecular) reaction is option B - the transition state is pentavalent.

Explanation:

SN2 reactions are a type of nucleophilic substitution reaction in which a nucleophile replaces a leaving group in a molecule. This reaction involves the simultaneous bond-breaking of the leaving group and the bond-forming of the nucleophile.

In an SN2 reaction, the nucleophile attacks the electrophilic carbon atom (the carbon atom bonded to the leaving group) from the front side, opposite to the leaving group. This is known as front-side attack or backside attack.

Transition State:
During the SN2 reaction, there is a transition state in which the nucleophile is partially bonded to the carbon atom, and the leaving group is partially detached. This transition state is characterized by a pentavalent carbon atom, meaning it has five attached groups. The nucleophile, leaving group, and three other substituents attached to the carbon atom are all present in the transition state.

The pentavalent transition state is formed because the nucleophile starts forming a bond with the carbon atom before the leaving group completely detaches. This transition state is highly unstable and short-lived, and it represents the highest energy point along the reaction pathway.

Reactive Intermediate:
In an SN2 reaction, there is no formation of a reactive intermediate. The reaction occurs in a single step, where the nucleophile directly replaces the leaving group without the formation of any intermediate species.

Product Formation:
In SN2 reactions, the product is formed directly from the transition state without passing through several transition states. Once the nucleophile has fully bonded to the carbon atom, the leaving group completely detaches, and the product is formed.

To summarize, the correct statement concerning an SN2 reaction is that the transition state is pentavalent (option B). This transition state represents the highest energy point in the reaction, and the nucleophile attacks the carbon atom from the front side opposite to the leaving group. The reaction occurs in a single step without the formation of any reactive intermediate, and the product is formed directly from the transition state.
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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. Polar solvents make the reaction faster as they

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The correct statement concerning a SN2 reaction isa)the reaction mechanism involve atleast one reactive intermediateb)transition state is pentavalentc)product is formed after passing through several transition statesd)nucleophile attacks from front side on which leaving group is presentCorrect answer is option 'B'. Can you explain this answer?
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