Chemical Forums
Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: Cantacoxinha on February 14, 2017, 04:56:25 PM
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I have three brief questions:
-why is nitromethane listed as a polar protic solvent on the Wikipedia article "Protic solvent"? I.e. why is it protic?
-with regard to organic synthesis, in particular the reactions proceeding via electrophilic substitution, what is the benefit of using solvents with high dielectric constant? I've been reading a couple of papers where it was stated that "acetonitrile was a solvent of choice... ...due to high dielectric constant". In general, when do we use high dielectric constant solvents in organic synthesis (apart from microwave synthesis)?
-why exactly is sulfuric acid a strong acid? I very well understand the common answer "because it is highly dissociated in water etc...", but I'm curious what intrinsically makes it (or any other strong oxoacid as nitric, perchloric etc.) a strong proton donor?
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1. In the wikipedia article "solvent" nitromethane is listed under polar aprotic. While the proton on nitromethane is pretty acidic, I wouldnt consider it a protic solvent. its a typo.
2. High dialectric constant essentially means its highly polar. Or more specifically, highly polarizable.
3. The way I like to think about bronstead-lowry acids is "how happy would this molecule be if it lost a proton and became an anion?" sulfuric acid has the 3 oxygen atoms with which to form resonance structures with if it loses a proton and becomes an anion, so it is quite happy to give away a proton.