Can someone please explain NMR and which hydrogen is most acidic?

[teefRcool]

Can someone please explain NMR and which hydrogen is most acidic?

I'm seriously lost with those could someone please explain how those work and how to pick which hydrogen is most acidic when given a huge molecule.

NMR i'm lost about how many peaks etc..?

Thanks a bunch if someone could help me out.

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[midwestboy]

Can someone please explain NMR and which hydrogen is most acidic?

I'm seriously lost with those could someone please explain how those work and how to pick which hydrogen is most acidic when given a huge molecule.

NMR i'm lost about how many peaks etc..?

Thanks a bunch if someone could help me out.

The most acidic hydrogen is usually the hydrogen located closest to the most electronegative or electron withdrawing atom. ie the Hydrogen attached to oxygen in alcohols or acids.

 

[teefRcool]

The most acidic hydrogen is usually the hydrogen located closest to the most electronegative or electron withdrawing atom. ie the Hydrogen attached to oxygen in alcohols or acids.

so what if you have ketone in the middle of a chain then what?

 

[allstardentist]

if i remember correctly, the alpha hydrogens are most acidic

 

[DAT Destroyer]

Can someone please explain NMR and which hydrogen is most acidic?

I'm seriously lost with those could someone please explain how those work and how to pick which hydrogen is most acidic when given a huge molecule.

NMR i'm lost about how many peaks etc..?

Thanks a bunch if someone could help me out.

The best way that I teach all my students about acidity is first to recall general guidlines..... Carboxy Acids > Phenols > alcohols > alkynes > alkenes > alkanes. while esters, ethers, and amides are not very acidic at all. I think that should help for the DAT. Now, what if there is a ketone or aldehyde ? The pka of an alcohol is about 16, while the aldehyde or ketone is about 20, thus less acidic. If a double alpha proton is present such as in 1,3- cyclohexanone, it would be more acidic because of resonance stabilization of the anion by both carbonyl groups. In Acetoacetic ester, look up the structure in your Orgo book, you would note that the double alpha proton has a pKa of 11, much more acidic than an alpha proton. I hope that helps

Regards Dr. Jim Romano NYU