Nmr

Question 1

Explain how properties of Si(CH3)4 is used

Answer 1

1. Dissolve the sample in solvent that has no H atoms so gives no signals in spectrum e.g. CCl4/ CDCl3
   - CCl4 = non polar so good solvent for non polar organic molecules
   - CDCl3= polar so good solvent for polar organic molecules
2. TMS is used as a reference to measure chemical shifts - all peaks are measured relative to this standard
   - TMS= inert so doesn’t react with the sample
   - volatile so easily removed from sample
   - gives one signal (12 protons in 1 environment)
   - signal is at v low ppm so it’s far away from other H signals

Question 2

Integration ratio H1 e.g. 2:3:3 tells u

Answer 2

How many protons in that environment