Perhaps easier than looking for the extra signal from the acid in proton NMR would be to compare the shifts of other peaks in either proton or especiallyin carbon NMR. Carbons in the vicinity of a protonated amine should come at different positions than those in a neutral amine. You could look for some examples to see what to expect.

I presume your reaction product is an amine and you want to know if you have isolated it as a free base or as a hydrochloride salt (ammonium chloride salt). In the 1H NMR spectrum of an ammonium chloride salt (R1R2R3N●HCl or R1R2R3HN+Cl-), you will observe a signal for the ammonium proton (+N-H ) which will be absent in the 1H NMR spectrum of the corresponding amine free base.

If you dissolve your salt in D2O (which might be the only solvent its soluble in) you most likely will not see the protonated compound, as that last proton that dissociates from the chlorine onto your compound is very labile and will exchange rapidly with solvent. Its possible if you use 10% D2O / 90% H2O (which is a common NMR solvent mixture) that you could see the protonated salt. Just a guess.

Too general question, as you do not provide the structure of your "salt", or at least to which atom the proton from HCl is attached. And the solvent is of utmost importance here - the content of water, hydrogen bond donations/acceptance ability of simple polarity will all influence the signal of RH+, which sometimes might be simply too much interchanged, or too broad, but sometimes is well distinguishable and narrow. And, btw. 10% D2O / 90% H2O is _not always_ a common solvent, especially if you are outside of biomolecular community...

You don't have to be in the "biomolecular community" to mix D2O with H2O.

In protic solutions exchangeable protons such as those in hydroxyl or amine group exchange protons with the solvent. And this occurs with D2O and MeOD. You need to use deuterated DMSO or any NMR solvents where the Deuterium from the solvent does not exchange with the protons of your molecule. I am not sure you can identify that signal specifically, however you can always try.

Hope it helps.

Good luck

My compound is not soluble in water. Also, the NMR in DMSO doesn't show any extra peaks. So most likely it is present as free salt.

Thanks for the answers.

You can use deuterated methanol

Hi Rajiv, what if you take a 15N NMR? From the shift of your Nitrogen- 15 spectrum it would be easy to distinguish between amine from ammonium. You can use the same solvent that you have 1H NMR in.

thanks

I think you should try to dissolve it in CDCL3 then check the nmr.. Also try the 2D nmr it may help...

Rajiv, An alternative to the N-15 NMR would be using an dipolar aprotic solvent in which your compound is soluble (DMSO-d6, THF-d8, ACN-d3 etc). If you want to confirm the extra proton you need to prevent its exchanging with the solvent. Usually DMSO is a good solvent to see all protons on organic compounds including the exchangeable ones (COOH, NH, OH). I agree with Dr. Flávio Alberto da Silva Figueira.

Thanks

Perhaps easier than looking for the extra signal from the acid in proton NMR would be to compare the shifts of other peaks in either proton or especiallyin carbon NMR. Carbons in the vicinity of a protonated amine should come at different positions than those in a neutral amine. You could look for some examples to see what to expect.

You take mass to know the new molecule formed by molecular mass of the compound and take nmr and ir to confirm the structure of the compound formed

I agree with Mark Minton. You should take the H1 NMR of the salt form in something like CDCl3. l would then deprotonate with a base and take the H1 NMR of the free base also in CDCl3. The protons in the CH2 or CH attached directly to the nitrogen will be shifted farther downfield in the salt form because of the effect of the positive charge on the nitrogen in the salt form.

Chemical shifts should tell.

Otherwise you may exchange HCl for acetic acid and check for acetate peak (or CF3COOH if you have F NMR)