NMR spectra in CDCl3, Proton exchange peak at 5.1 PPM observed at low temperature?

I found NMR In CDCl3, an unknown peak observed at 0, -5, -10, and -15 degrees celcius. The peak value is 5.1 ppm broad peak, which is not observed in the room and high temperature. Please suggest...

29 April 2021 889 7 View