UV/Vis Spectroscopy

Empirical Rules Benzoyl Derivatives

Empirical Rules Benzoyl Derivatives
Base values:
  R = alkyl or ring residue   l = 246 nm
  R = H   l = 250 nm
  R = OH, OR   l = 230 nm
Increment for each substituent:
  -Alkyl or ring residue o,m   3
  p 10
  -OH, -OR o,m   7
  p 25
  -O- o,m 11
  p 20
  -Cl o,m   0
  p 10
  -Br o,m   2
  p 15
  -NH2 o,m 13
  p 58
  -NHC(O)CH3 o,m 20
  p 45
  -NHCH3 p 73
  -N(CH3)2 o,m 20
  p 85

Example 1:

Parent chromophore:   246 nm
o-Ring residue:   3 nm
m-Br:   2 nm
Calculated:   251 nm
Observed:   253 nm

Example 2:

Parent chromophore:   230 nm
p-OH:   25 nm
m-OH: 2 x 7 = 14 nm
Calculated:   269 nm
Observed:   270 nm

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