organic chem Flashcards
more conjugated system = ______ energy of transition = ______ wavelength of maximum absorbance
lower energy
greater wavelength
pi/NB electrons can be excited by UV to higher-energy antibonding orbitals. the less gap = the more excited = ______ wavelengths
longer (lower frequency/energy)
α-state
nuclei aligned with the magnetic field
β-state
nuclei not aligned
chemical shift (δ) units
parts per million
what do we use to set the reference peak of NMR
TMS, skip the first peak
most H atoms come into resonance ___ to ____ ppm downfield from TMS
0 to 10
what makes peaks go to the left
being attached to more EN atoms, they pull the electron density away
when are H too close
when they are within three bonds away
subpeaks
n + 1 (n = # of adjacent H)
aldehyde chemical shift
9-10 ppm
COOH chemical shift
10.5-12
H of aromatic ring chemical shift
6-8.5
alkyne carbon chemical shift
2-3
alekene chemical shift
4.6-6
aromatic chemical shift
6-8.5
simple distillation
separates liquids below 150 degrees C, 25 degree difference
vacuum distillation
boiling points over 150 degrees
fractional distillation
separates liquids with similar boiling points
