For each pair, predict the stronger nucleophile in the SN2 rea...

Question

For each pair, predict the stronger nucleophile in the SN2 reaction (using an alcohol as the solvent). Explain your prediction.

e. (CH₃)₃N or (CH₃)₂O

f. CH₃COO^– or CF₃COO^–

Accepted Answer

Hey everyone and welcome back in today's video, we are going to look at the following problem using alcohol as a solvent figure out which compound or I and in each pair is the stronger nuclear file in the SN two reaction explain your prediction and we have two different nuclear files in reaction number one in particular we have tri ethyl amine. So that's nitrogen. It has a long pair and three ethyl groups, bonnets. It versus Di Ethyl Ether, right. That's oxygen with two lone pairs and see athlete groups. These out Kielce obsessions are exactly the same. The main importance in our comparison should concentrate around nitrogen and oxygen. When we think about nitrogen and oxygen, there are several ways to think about nuclear Felicity. Whether we think about the size of the atom or electro negativity, recall that if we think about size greater atomic radius r or greater size implies that the atom is more polarized able, which implies that it must be a better nuclear file. So that's one way of thinking about this problem. Which of the two is bigger, nitrogen or oxygen recalled that whenever we go from left to right along the periodic table, the atomic radius decreases and therefore the radius of nitrogen is greater than the radius of oxygen. According to this concept. Since nitrogen is bigger, it's more polarized able. And it must be a better nuclear file. In addition to that if we think about the concept of electro negativity, oxygen or basically let's just explain what that means. A more electoral negative adam has a greater tendency to hold electrons near to its nucleus simply speaking, a more electro negative atom will hold these electrons more tightly and it will not be able to donate them that easily into the formation of a new bond because oxygen is more electro negative. In other words, electro negativity of oxygen is greater than that of electro negativity of nitrogen. Since oxygen is closer to flooring, right? And flooring is the most electro negative element due to the greater of electro negativity, oxygen is not that willing to donate its lone pair into the formation of a new bond while nitrogen is less electra negative and therefore it's more capable of forming a new bond in a nuclear attack in an sN two reaction. And therefore this is another way of thinking about it. In other words, the first structure try ethyl amine is a better nuclear file because nitrogen is more able to donate an electron pair than the more electro negative oxygen. Similarly, if we look at the next part of the problem, We are considering two structures. One of them, both of them are carb oxalate ions. So we may state we have C. 00. Negative and then in particular here We have c. S. two, C. 3. The other one looks very similar, But now we have CF two CH 3. So there are two Florian Adams added here. If we compare them, we immediately recognize that the aspect of comparison is the inductive effect. The indicative effect in particular tells us that due to the presence of electron withdrawing or donating groups, actually let's change the color of that box to make sure that we understand that this is conceptual information. The inductive effect tells us that due to the presence of electron withdrawing or donating groups, the charge on our nuclear file might either increase or decrease depending whether elections are donated or withdrawn. In particular. The two flooring atoms present here that have now replaced the original two hydrogen in the first structure. And that's the main difference between them. They are more electro negative. Now, what happens is that flooring atoms due to their electro negativity? There are electron withdrawing, right? So just that electron withdrawing effect, the negative charge and oxygen would not be so concentrated, it would be more de localized. It's already withdrawn here. We also have residents because we have a carbon neutral group. But just the presence of these flooring atoms, the electron density is dragged even more away from it. So that said, this negative charge is less dance or more de localized due to electron withdrawing Lorraine Adams here. We don't have these florins over here. So there's nothing that can withdraw the electron density from this oxygen more than they are already withdrawn by the carbon group. So there's no additional inductive effect here, meaning this negative charge is more than and due to the fact that this charge negative charges more dance, We may donate these elections into an essence to reaction more easily, meaning the first structure must be a better nuclear file than the second one, due to the fact that it's not experiencing that inductive effect of the two electron withdrawing groups. That said, the correct answer to this multiple choice question is B. However, if you have any questions, don't have states, leave your comment down below and thank you for watching.

For each pair, predict the stronger nucleophile in the SN2 reaction (using an alcohol as the solvent). Explain your prediction.
e. (CH₃)₃N or (CH₃)₂O
f. CH₃COO^– or CF₃COO^–

Key Concepts

Nucleophilicity

Solvent Effects in SN2 Reactions

Steric Hindrance

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