Broad-band hydrogen decoupling

Compound Qhas the molecular formula CyHs- The broad-band proton decoupled spectrum of Qhas signals at 8 50 (CH), 85 (CHs). and 144 (CH). On catalytic hydrogenation Qis converted to R (CyHig)- Propose structures for Qand R... 

A technique that completely removes C-H coupling is called broad-band hydrogen (or proton) decoupling. This method anploys a strong, broad radio-frequency signal that covers the resonance frequencies of all the hydrogens and is applied at the same time as the... 

There are many possible variations on this simple pulse sequence. For example, in Chapter 4 we learned that it is possible to transmit two signals into the sample. In NMR spectroscopy, a pulse sequence similar to that shown in Figure 10.1 is transmitted at the absorption frequency of the nuclei. At the same time, a second transmitter, tuned to the frequency of the hydrogen ( H) nuclei in the sample, transmits a broad band of frequencies to decouple the hydrogen nuclei from the nu-... 

The broad-band-decoupled NMR spectrum (125 MHz, 6 in ppm relative to TMS) of a CDCI3 sample with 20 common solvents (0.05-0.4 vol%) shown below serves as a guide to identify possible solvent impurities. Chemical shifts of signals marked with an asterisk ( ) may change up to a few ppm if the sample contains solutes having functional groups that can form hydrogen bonds. 

---