u/tungtungtung337 — reddlx

Confusion on regioselectivity

i'm not sure if i misunderstand regioselective, but i think of it as a reaction producing multiple constitutional isomers with a major/minor product

however, the answer key says that because multiple acetonides can form, the reaction is neither regioselective or stereoselective.

isn't a defining part of regioselectivity having two products that are constitutional isomers?

(image 2 for acetonide group the question provided)

u/tungtungtung337 — 4 days ago

▲ 4 r/chemhelp

Entropy differences in aqueous solutions when the solute is a salt vs a hydrophobic molecule

An answer to a practice problem I was doing mentioned that salt dissolved in an aqueous solution increases the entropy by disrupting the ordered hydrogen bonds between water.

But looking to the hydrophobic effect, the addition of a hydrophobic solute decreases the entropy of water by making it too ordered.

Is there a way to qualitatively reason this difference out? Does it have to do with the polarity of salts? Or is it related to how hydrophobic molecules are generally larger than salts?

reddit.com

u/tungtungtung337 — 9 days ago

▲ 5 r/chemhelp

Does an R group attached to Benzene affect the chemical equivalence?

In the answer key to one of the practice problems I'm doing, it mentions that protons B&C and A&D are chemically equivalent.

I'm a bit confused, wouldn't the electronic environments be different due to not having a plane of symmetry through the molecule (the R group with an oxygen, ester, and amide), which would produce 4 separate NMR signals?

If there's diamagnetic anisotropy at work, wouldn't that cause protons ABCD to all be equivalent?

https://preview.redd.it/fep954pc4a8h1.png?width=502&format=png&auto=webp&s=ee02827e8b079117de1b93b0ee197d44d60f8e31

reddit.com

u/tungtungtung337 — 16 days ago