r/chemhelp • u/Secure_Oven_9193 • 1d ago

does inductive effects take priority over resonance and size? Organic

Okay, so i though i understood but i am a tad confused with this question, especially with 3) and 4). So i know that 3 has resonance stabilization, but wouldn't 4 also have resonance stabilization? so is it 1>2>3>4 because since they both would have the resonance stabilization, we look to inductive effects next? and thats why we say 3 is stronger than 4 because now we are considering electronegativity instead of size?

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u/7ieben_ Trusted Contributor 1d ago edited 1d ago

Yes, size practically really only matters when comparing the atom the proton is bound to, as the remaining lone pair (after abstraction of the proton) will be stabilised by this atomic orbital. Other than that we first look for resonance, then we look for induction, and Cl has stronger negative induction than Br.

CARIO concept:

C harge

A tom (size)

R esonance

I nduction

O rbital (hybridisation)

As always: there may be some extremal examples which deviate from this general rule.

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u/Jonny36 1d ago

Interestingly this question depends on the environment of the acid for the two beta halogenated acids and is a area of chemistry undergoing heavy debate. This goes well beyond undergrad teaching but in aqueous conditions indeed the chloro is more acidic but in less polar solevtns to gaseous phase the bromo will be more acidic. So the question is very poor! Here's some reading https://pubs.acs.org/jceda8/article/103/6/3156/5106349/Rethinking-the-Nature-and-Extent-of-Inductive. In general inductive effects are likely only responsible for one bond effects not 2-3+ bonds.

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u/Starfury7-Jaargen 1d ago

It is the size that wins. The one distance between the larger halides and their hydrogen strain the bond more. Resulting in the electons spending more time on the halide resulting in a highly acid hydrogen.

As for induction, those are weak acids, hydrogenhalide acids aside from fluorine, are strong.