I have recently purchased cdcl3. The water peak is at 1.62. As per literature it should be at 1.56. Can someone tell me is this normal or is a impurity. Also is there anyway we can quantify the undeuterated chcl3 which appears at 7.26.

 

I have recently purchased cdcl3. The water peak is at 1.62. As per literature it should be at 1.56. Can someone tell me is this normal or is a impurity. Also is there anyway we can quantify the undeuterated chcl3 which appears at 7.26.

 

 

Why are you trying to quantify it? You can normally get a good idea of how good / bad it is by looking at the spectra of something. In any case, you could add a reference of known concentration to your CDCl3 and compare integration. If you know the volume of CDCl3 in the tube, you should be able to work out the % impurity.

 

Water peaks do not always come up at 1.56 ppm. It can and often does vary. I wouldn't be too concerned by it, provided you are sure it is water.

I could be wrong about this, but perhaps the chemical shift is concentration-dependent. As the concentration of water in the chloroform increases, there is more opportunity for hydrogen bonding. I don't have a citation handy, however.

Can someone save me the trouble of looking up the shifts for HOD and CHCl₃ in CDCl₃?

Those will be present in you add ordinary water (eg, from the air) to CDCl₃

CHCl3 is 7.26ppm. Water varies, but it is generally visible at 1.56 ppm. BabockHall is correct in stating that H-bonding can and will change this, however.