3.15 NMR Flashcards
which 3 techniques do chemistry use to deduce structure of compounds
mass spec
ir spec
NMR
what does NMR stand for
nuclear magnetic resonance
what is the property called that atoms with an odd mass number have
nuclear spin, can behave like tiny magnets
what do atoms with an odd mass number in sample do when placed ina a magnetic field
either align with or against magnetic field
resonance
combination of magnetic field and radio frequency radiation causes nuclei to absorb energy and flip between the two nucear spin states
what do nuclei in different chemical environments require different amounts of
energy to flip between states
what can the energy required to cause resonance be
detected and processed to give NMR spectrum
solvent
deuterated solvents such as CDCL3 are used
reference
tetra methyl silene
where does TMS standard appear in NMR spectrum
0ppm
why is TMS suitable standard to use
inert, non toxic, volatile
12 equivalent Hs- one strong, sharp signal
what scale do chemists use to compare the positions of peaks in an NMR spectrum
chemical shift
what are the units of chemical shift
ppm
what does the chemical shift of a particular nucleus depend on
its molecular environment
C13 NMR: number of peaks =
number of different carbon environments
