Justify on a reaction coordinate diagram the fact that a strong base like sodium amide (NaNH 2 ) results in a faster E2 elimination than does sodium hydroxide (NaOH).

Welcome back, everyone explain the reason why stronger bases such as sodium hydride, nah lead to a faster e two elimination compared to sodium metox side. DH three. On a by using the reactions coordinate and diagram, we're given our starting material which is an L cal chloride which reacts fast with sodium hydride and slow with sodium metox side to produce an L Ken in an elimination reaction. What we want to do for this problem is simply draw a reaction coordinate diagram. Now, on the vertical axis, we are plotting our energy and on the horizontal axis, we can state the coordinate of the reaction or simply time the starting material is drawn and the final product is drawn at the end at a lower energy because the reaction is exothermic. And now we noticed that we are given two different activation energy values. The reason why we're doing this is because if the reaction is fast, let's recall that reaction rate increases with a decrease in the activation energy. So they are inversely proportional the lower the activation energy, the faster the reaction rate. And we can say that if sodium hydride produces a fast reaction, then it will have an activation energy labeled in blue, which is lower than deactivation energy labeled in green. So let's assign our basis. We have sodium hydride. And for the green pathway, we will be using sodium met oxide. And simply speaking, this is the reason, stronger basis would essentially allow us to achieve a lower activation energy barrier because stronger bases have a better ability to abstract a proton and therefore produce a more stable transition state. So we can simply summarize our answer as follows. We can say that using a stronger base, what lead to a lower activation energy E A? And when that activation energy is lower, the reaction apparently proceeds faster. And once again, the reason why a stronger base is capable of doing this is simply because stronger bases have a better ability to abstract an acidic hydrogen and stabilize the transition state. Therefore, once again, our final answer is using a stronger base would lead to a lower activation energy. Thank you for watching.

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36. Synthetic Polymers1h 49m

8. Elimination Reactions

E2 Mechanism

Organic Chemistry

8. Elimination Reactions

E2 Mechanism

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Problem 40

Textbook Question

Justify on a reaction coordinate diagram the fact that a strong base like sodium amide (NaNH₂) results in a faster E2 elimination than does sodium hydroxide (NaOH).

Verified step by step guidance

Understand the concept of E2 elimination: E2 elimination is a bimolecular reaction where a base abstracts a proton from a β-carbon, and simultaneously, the leaving group departs from the α-carbon, forming a double bond. The reaction rate depends on the strength of the base and the ability to abstract the proton efficiently.

Compare the basicity of sodium amide (NaNH₂) and sodium hydroxide (NaOH): Sodium amide is a stronger base than sodium hydroxide because the conjugate acid of NaNH₂ (NH₃) is less acidic than the conjugate acid of NaOH (H₂O). This means NaNH₂ has a higher tendency to abstract protons.

Relate basicity to the reaction coordinate diagram: A stronger base like NaNH₂ lowers the activation energy (ΔG‡) for the E2 elimination process because it can more effectively abstract the β-hydrogen, making the transition state easier to achieve. This results in a faster reaction rate.

Illustrate the reaction coordinate diagram: On the diagram, the y-axis represents the free energy, and the x-axis represents the reaction progress. The curve for NaNH₂ will show a lower activation energy peak compared to NaOH, indicating a faster reaction due to the stronger base.

Conclude the justification: The faster E2 elimination with NaNH₂ compared to NaOH is due to the stronger basicity of NaNH₂, which reduces the energy barrier for the reaction. This is reflected in the reaction coordinate diagram by a lower activation energy for the transition state when NaNH₂ is used.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

E2 Elimination Mechanism

The E2 elimination mechanism is a bimolecular reaction where a strong base abstracts a proton from a substrate while a leaving group departs simultaneously. This concerted process results in the formation of a double bond. The rate of an E2 reaction depends on the strength of the base and the stability of the leaving group, making the choice of base critical for reaction speed.

Reaction Coordinate Diagram

A reaction coordinate diagram visually represents the energy changes during a chemical reaction. It plots the energy of the system against the progress of the reaction, illustrating the transition states and intermediates. In the context of E2 eliminations, the diagram helps to compare the activation energies of reactions involving different bases, highlighting how a stronger base can lower the energy barrier and accelerate the reaction.

Base Strength and Nucleophilicity

Base strength is a measure of a base's ability to accept protons, while nucleophilicity refers to a species' ability to donate electron pairs. Sodium amide (NaNH₂) is a stronger base than sodium hydroxide (NaOH), making it more effective at deprotonating substrates in E2 reactions. This increased basicity leads to a lower activation energy and a faster reaction rate, as depicted in the reaction coordinate diagram.

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