NMR spectroscopy Flashcards
What is TMS (Si(CH3)4)?
the standard against which the bond environment peaks are measured in NMR spectroscopy
Why is TMS a suitable substance to use as a standard?
it contains 4 identical carbon and hydrogen environments so its chemical shift value is 0
What does chemical shift depend on?
the molecular environment
What must 1H NMR samples be dissolved in? Why?
in non-hydrogen-1 containing solvents e.g. deuterated solvents or CCl4, because these will not produce any peaks
What does NMR stand for?
nuclear magnetic resonance
What do integrated spectra indicate?
the relative numbers of 1H atoms in different environments
What does NMR tell us?
the position of 13C or 1H atoms in a molecule (it is an analytical technique)
What are deuterated solvents?
solvents containing deuterium (an isotope of hydrogen with 1 proton and 1 neutron)
Explain the n+1 rule with regards to the splitting pattern in 1H spectra
n = the number of hydrogens on the adjacent carbon(s)
singlet = no H on adjacent Cs
doublet = 1H
triplet = 2H
quartet = 3H
Why is 13C used instead of 12C?
12C has no nuclear spin but 13C does
What is chemical shift (δ) measured in?
parts per million (ppm)
What is chemical shift?
the difference in frequency between the resonating nucleus and that of TMS
What does the area of each peak in 1H NMR show?
the number of hydrogen atoms producing that peak
