Why are nucleophiles good bases

The two facts combined make sure that NH3 de-protonates H2O and not the other way around. Hi, im wondering how to order these nucleophiles here: NEt3, PEt3 and pyridine.

As you already told, PEt3 is surely more nucleophile than NEt3. But what about pyridine? Is it more nucleophile than PEt3 due to steric hindrance? Great help.. Plz give me good explanation for it. I m counting on you. Does basicity of a compound has anything to do with its size or steric factor? Because anything it has to do is just to take out a proton from a molecule.? The pKa of t-BuOH is about 18 versus 16 for methanol, so for a first-order analysis, no. There are certain reactions e.

Hi there. Can you please help me in my confusion? In a case, where I am given a tertiary alkyl and H2O. How do I know if the H2O will be acting as a base and undergo elimination or, acting as a nucleophile and undergo substitution?

I assume you mean that you have a tertiary alkyl halide, in the presence of H2O. The first step will be loss of halide ion to give a carbocation. What happens next could either be attack of the carbocation by water SN1 or deprotonation adjacent to the carbocation to give an alkene elimination — E1. Both pathways will occur. Your both statements produce contradiction against each other.

Indicate which reagents in the pair is expected to be more nucleophilic towards ch3br in ethanol and why? What if the two groups, -OH alcohol tert position and -COOH primary position , present on the same molecule, then which one would be better nucleophile? If we are comparing neutral OH with neutral COOH, with equal steric hindrance, then the stronger nucleophile would be the group that is the most basic.

We know this because the pKa of protonated R-OH is about If there is significant difference in steric hindrance then this would affect the relative nucleophilicity to some extent. You are correct that protic solvent would retard the nucleophilicity of both these species, and polar aprotic solvent would augment it. Also, putting a substituent on a C-H ortho to two substituents tends to be disfavored. Your email address will not be published. Save my name, email, and website in this browser for the next time I comment.

Notify me via e-mail if anyone answers my comment. This site uses Akismet to reduce spam. Learn how your comment data is processed. Next The Three Classes of Nucleophiles.

Great, great question. A polar aprotic solvent like acetone or dimethylformamide preferentially solvates cations, leaving an almost "bare" nucleophile.

This increases its nucleophilicity. Nucleophilicity refers to "how much" a reactant wants to "find" a positive charge. In other words, it measures the instability of the reactant's negative charge.

Basicity refers to "how much" a reactant wants to "find" a Hydrogen ion. In both of these, the underlying drive is the same--both the base and the nucleophile want to stabilize their negative charge with a positive one. So, the more unstable the negative charge of a reactant is, the higher its nucleophilicity AND its basicity. The defining difference, then, is how a reactant behaves in the presence of a substrate that contains an electrophile or an abstractable hydrogen.

Consider CN. It will tend to act as a nucleophile and attack an electrophile. A reactant can be a good nucleophile and a good base and act as either. As you can see it is very nuanced, and you have to consider the whole reaction when determining nucleophilicity and basicity. Nucleophile vs. Base Strength. Key Questions What are some examples of nucleophiles and strong bases? With a few exceptions, a strong nucleophile is also a strong base. Ernest Z. What determines the nucleophile's strength?

Charge Nucleophilicity increases as the density of negative charge increases. As electronegativity increases, nucleophilicity decreases. What is the difference between a nucleophile and a stong base? This is a tricky one, but to sum it up, nucleophiles tend to be less basic. It will tend to act as a nucleophile and attack an electrophile A reactant can be a good nucleophile and a good base and act as either.

I have to sign off now, but feel free to ask more questions or add more detail. Hope it helps! What are some examples of nucleophiles and strong bases? Can a strong nucleophile be a weak base? The reason why basicity and nucleophilicity correlate rather well but not completely comes from the differences between the electrophilic properties of carbon atoms and protons using the HSAB principle one might describe the difference like this Add a comment.

Active Oldest Votes. Nucleophilicity is a kinetic phenomenon. Basicity is a thermodynamic phenomenon. Improve this answer. Ben Norris Ben Norris 41k 8 8 gold badges silver badges bronze badges. Read the other answer for a more specific explanation of the phenomena. Jayden Price Jayden Price 1 1 1 bronze badge. Vikas Avasthi Vikas Avasthi 9. Does it have anything to do with charge density?

This seems like a major oversimplification. Featured on Meta. Now live: A fully responsive profile. Linked 1. See more linked questions.