The proton NMR peak of water changes with respect to the solvent; e.g. 1.56 in CDCl3, 3.33 in DMSO-d6, 0.40 in benzene-d6 etc.
Not only water even any material peaks changes with respect to the solvent. Addition to the inherent characteristics of the material , the interaction of the material with the solvent also important in defining the peak values.
In water proton attached to the electronegative atom so it is considered as a exchangeable proton. If the NMR solvent is able to make hydrogen bond the then peak value going to be more down field, if not peak value going to be low. CDCl3 has ability to make hydrogen bond due to the polar bond between the C-Cl but not benzene. That is the reason water shows at 1.56 in cdcl3 and 0.40 in benzene.
Right. In addition to what Yalagala said, there are solvents (like CD3OD) or compounds in the sample, which contain hydroxy groups. These are going to exchange fast with the hydroxy group of water making them indistinguishable on NMR. Furthermore, the hydrogen ions of acidic solvent or compound (or compounds which can be readily protonated) also exchage with water causing a large downfield shift.
Even beside the effects mentioned above, the magnetic susceptability of different solvents are different. Thus, the magnetic field at a water impurity in chloroform will be different from that in benzene even without any direct interaction between molecules. I'm not sure which effect dominates.
Hydrogen bond acceptor solvents such as DMSO-d6 or acetone-d6 affect the chemical shifts of protons near a good hydrogen bond donor such as OH in any compound. This effect is particularly marked (and useful for structure elucidation) with pyridine-d5.
Dear All,
I done NMR spectra in methanol for ionic liquids containing HSO4, CH3SO4 and CF3SO3. The spectra is ok but the NMR peak of methanol appera at 5.15 instead of 4.87. Please give me solid reason
in C13 NMR how much peak is possible if two cyclohexane connecting by ethyl to one another.
In general, the stronger intermolecular hydrogen bond between the NMR solvent and water molecules, the more their 1H NMR signal appears at the lower magnetic field (higher frequency). And this is the reason why the 1H NMR signal of water is observed at about 0.4, 1.5, 3.3, 4.8 and 5 ppm for deuterated forms of benzene, chloroform, dimethyl sulfoxide, water and pyridine, respectively.
The water peak vary in the proton- NMR spectroscopy when recorded in different solvents is due to variation of hydrogen bonding interactions with different solvents.
Dr. Amir Sada I believe that signal in 4.87 ppm is not of CH3 of methanol but the signal of water in methanol.
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