Which is a better nucleophile? e. HO − or - NH 2 in NH 3 f. HO − or - NH 2 in DMSO

Welcome back, everyone. Which of the following P CS is a better Nu Coyle a metox site or methyl amide and ammonia and B metox side or methyl amide and dimethyl sulfoxide. First of all, we noticed that we are comparing two, exactly the same species in two different solvents. Ammonia is a polar product solvent because it can form hydrogen bonds. There's hydrogen bonnet to an electron ngen atom. The methyl sulfoxide is a polar a product solvent that we commonly use in essence or reactions. We may recall that there's a sulfur oxygen double bond and two metal groups bonded to sulfur. So there are no hydrogen atoms bonded to high electron hetero atom. Let's recall that in polar product solvents, nu Felicity increases with an increase in size. That's because larger nuclear files are more polarized and they become stronger nuclear files. And in polar a product solvents, nuclear Felicity increases with a decrease in size because stronger NU files are also stronger bases and polar a product solvents. However, in this problem, we are not going to consider any sizes because what we noticed is that both of our nu files are negatively charged. They are quite similar in their structures. So we have metox side and methyl amide excluding hydrogen and the metal group, we are comparing oxygen and nitrogen which belong to the same period of the periodic table, meaning their sizes are comparable. And whenever we are comparing two atoms from the same period, we want to recall the concept of electro negativity, which is more important. And then it doesn't really matter what sort of size our nu file corresponds to. So whether we use a polar product solvent or a pool or a product solvent, it doesn't really matter. Let's recall that the electron negativity of nitrogen is lower than the electron activity of oxygen. Since when we go from left to right across a period, electron activity increases. And if NGEN is less electron negative, this means it has a greater tendency to share a slow pair of electrons into the formation of a new bond. So it will be a better new profile than oxygen, simply speaking because it is less electron negative. And therefore, because we did not worry about size, we do not need to worry about this type of solvent as well. In each case, we can say that methyl amide will be a better nu coile in both types of solvents. Thank you for watching.

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1. A Review of General Chemistry5h 5m
2. Molecular Representations1h 14m
3. Acids and Bases2h 46m
4. Alkanes and Cycloalkanes4h 17m
5. Chirality3h 39m
6. Thermodynamics and Kinetics1h 22m
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8. Elimination Reactions

Nucleophiles and Basicity

Organic Chemistry

8. Elimination Reactions

Nucleophiles and Basicity

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3:42 minutes

Problem 12e,f

Textbook Question

Which is a better nucleophile?
e. HO⁻ or ^-NH₂ in NH₃
f. HO⁻ or ^-NH₂ in DMSO

Verified step by step guidance

Step 1: Understand the concept of nucleophilicity. Nucleophilicity refers to the ability of a species to donate a pair of electrons to an electrophile. It is influenced by factors such as charge, electronegativity, solvent effects, and steric hindrance.

Step 2: Analyze the nucleophiles in question. Both HO⁻ (hydroxide ion) and NH₂⁻ (amide ion) are negatively charged, which generally makes them strong nucleophiles. However, their relative nucleophilicity depends on the solvent and their intrinsic properties.

Step 3: Consider the solvent in part (e), which is NH₃ (ammonia). NH₃ is a polar protic solvent, meaning it can form hydrogen bonds with nucleophiles. Polar protic solvents stabilize smaller, more electronegative nucleophiles like HO⁻ through hydrogen bonding, reducing their nucleophilicity. NH₂⁻, being less electronegative and larger, is less stabilized by hydrogen bonding and thus remains a stronger nucleophile in NH₃.

Step 4: Consider the solvent in part (f), which is DMSO (dimethyl sulfoxide). DMSO is a polar aprotic solvent, meaning it does not form hydrogen bonds with nucleophiles. In polar aprotic solvents, nucleophilicity is less affected by solvent stabilization, and the intrinsic properties of the nucleophiles dominate. NH₂⁻ is still a better nucleophile than HO⁻ because nitrogen is less electronegative than oxygen, making NH₂⁻ more willing to donate its lone pair of electrons.

Step 5: Summarize the findings. In NH₃ (polar protic solvent), NH₂⁻ is a better nucleophile than HO⁻ because it is less stabilized by hydrogen bonding. In DMSO (polar aprotic solvent), NH₂⁻ is also a better nucleophile than HO⁻ due to its lower electronegativity and greater intrinsic nucleophilicity.

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Key Concepts

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

Nucleophilicity

Nucleophilicity refers to the ability of a species to donate an electron pair to an electrophile, forming a chemical bond. It is influenced by factors such as charge, electronegativity, and solvent effects. Stronger nucleophiles are typically negatively charged or have lone pairs that can be readily donated. Understanding nucleophilicity is essential for predicting reaction mechanisms in organic chemistry.

Solvent Effects

The solvent can significantly influence nucleophilicity by stabilizing or destabilizing the nucleophile. Protic solvents, like ammonia (NH3), can solvate nucleophiles through hydrogen bonding, often reducing their reactivity. In contrast, aprotic solvents, such as dimethyl sulfoxide (DMSO), do not solvate anions as effectively, allowing nucleophiles to remain more reactive. Recognizing the role of solvents is crucial for evaluating nucleophilic strength in different environments.

Comparative Nucleophilicity

When comparing nucleophiles, factors such as charge and steric hindrance must be considered. For example, hydroxide (HO−) is generally a stronger nucleophile than amide (−NH2) in protic solvents due to its negative charge. However, in aprotic solvents, the relative nucleophilicity can change based on the solvent's ability to stabilize the nucleophiles. Analyzing these comparisons helps in predicting which nucleophile will be more effective in a given reaction.

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