For the reaction between alkyl halide and OH- increase in solvent polarity generallya)Decreases the rate of SN1 reaction b)Increases the rate of SN1 reactionc)Increases the rate of SN2 reaction d)Does not alter the rate of SN1 and SN2 reactionCorrect answer is option 'B'. Can you explain this answer?

Question

For the reaction between alkyl halide and OH- increase in solvent polarity generallya)Decreases the rate of SN1 reaction          b)Increases the rate of SN1 reactionc)Increases the rate of SN2 reaction          d)Does not alter the rate of SN1 and SN2 reactionCorrect answer is option 'B'. Can you explain this answer?

Answer

The effect of solvent polarity on the reaction between alkyl halide and OH-

Solvent polarity plays a significant role in determining the rate of reactions involving alkyl halides and nucleophiles such as OH-. The polarity of a solvent refers to its ability to dissolve polar compounds and its tendency to form hydrogen bonds. Generally, an increase in solvent polarity enhances the rate of reactions involving alkyl halides due to the following reasons:

1. Solvation of reactants:
When an alkyl halide and OH- are dissolved in a polar solvent, the solvent molecules surround and solvate both the reactants. In a highly polar solvent, the solvent molecules form strong interactions with the charged species (ions) present in the reaction mixture. This solvation stabilizes the transition state and lowers the energy barrier for the reaction to occur, thereby increasing the reaction rate.

2. Stabilization of intermediate:
In the case of SN1 (substitution nucleophilic unimolecular) reactions, the rate-determining step involves the formation of a carbocation intermediate. In a polar solvent, the solvent molecules can stabilize the positive charge on the carbocation through ion-dipole interactions. This stabilization reduces the energy required to form the carbocation and increases the rate of the overall reaction.

3. Enhanced nucleophilic attack:
In SN2 (substitution nucleophilic bimolecular) reactions, the nucleophile attacks the alkyl halide molecule from the backside, resulting in the displacement of the leaving group. In a polar solvent, the nucleophile is more effectively solvated, which reduces its tendency to interact with the solvent molecules and increases its availability for the reaction. This increased nucleophilic availability leads to a higher reaction rate.

Conclusion:
Based on the above explanations, it can be concluded that an increase in solvent polarity generally increases the rate of both SN1 and SN2 reactions involving alkyl halides and OH-. Therefore, the correct answer is option 'b' - an increase in solvent polarity increases the rate of SN1 reactions.

Similar Chemistry Doubts

For the reaction between alkyl halide and OH- increase in solvent polarity generally

Which is correct statement if N2 is added at equilibrium condition?

Consider an exothermic reaction,As a temperature increases

For a equilibrium H2O(s) → H2O(l) which of the following statements is true

At constant temperature, the equilibrium (Kp) for ... morethe decomposition reaction is expressed by where, p = pressure,X = extent of decomposition. Which one of the following statement is true

Top Courses for Chemistry

Suggested Free Tests

Related Content

Schools

Competitive Examinations

Quick Access Links

Technical Exams