Why does acetone promote sn2 pathway

Bromide and chloride are too small, leaving a gap of empty space around them, and the distance to sodium cations is larger than optimal. It becomes energetically more favorable for the sodium and halide ions to simply fall out of solution than arrange themselves in a solvated cage.

This drives the reaction forward in accordance with Le Chatelier's principle. While this relates to the solubility of the halide salts, maybe it can also serve to speculate on the mechanism of the Finkelstein reaction.

This is far from rigorous research, so I'd take it with a grain of "salt" as a correct answer, but thought it might be interesting to think about. NaI in acetone is the reagent used in Finkelstien reaction. Alkyl halides are treated with the reagent to give alkyl iodides. The important aspect of this reaction is that the reaction is driven forward because of the lower solubility of the products NaCl and NaBr in acetone even though I- is a weak nucleophile.

First of all the steric hindrance around the carbon atom should be least i. If solvent is aprotic and nucleophile is fairly good strength : like DMF, acetone etc. Thus SN2 mechanism is favoured more. Sign up to join this community. The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more. Is I- not considered a weak nucleophile? Ask Question. Asked 2 years, 10 months ago.

Active 2 years, 3 months ago. Viewed 10k times. Improve this question. Mason 2 2 silver badges 11 11 bronze badges. Ben Ben 21 1 1 silver badge 2 2 bronze badges. In most of the sources I read about this, they all just say NaI is good example of an SN2 reaction, so it seems like that is the case in most scenarios, and I'm just trying to understand why.

It also also happens to be a great leaving group, so substituting for iodide and having it stay on the product is hard. Ernest Z. Jan 5, Nucleophiles are more nucleophilic in polar aprotic solvents.

Related questions What are SN2 reactions? What are common mistakes students make with nucleophilic substitutions? Explain nucleophilic substitution of alkyl halides? How does an SN2 reaction affect stereochemistry? How does concentration affect SN1 reactions? How does concentration affect SN2 reactions?