Using Woodward-Fieser's Rule, Calculate Wavelengths of Maximum UV Absorption For Following Compounds [PDF]

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1. Using Woodward-Fieser's rule, calculate wavelengths of maximum UV absorption for following compounds:

a)

b)

Base value: alkyl groups:

217 nm 3x5

c)

Base value:

15 nm

alkyl groups:

253 nm 2x5

10 nm

calculated:

232 nm

calculated:

263 nm

observed:

234 nm

observed:

256 nm

d) Base value: alkyl groups or ring residues:

e) 4x5

Exocyclic double bond:

253 nm 20 nm

5 nm

calculated:

278 nm

observed:

275 nm

f)

Base value: alkyl groups or ring residues: Exocyclic double bond: extra conjugation: calculated: observed:

5x5

214 nm 25 nm

3x5

15 nm

1x30

30 nm 284 nm 283 nm

g)

Base value:

215 nm

α-alkyl groups or ring residues:

1x10

10 nm

β-alkyl groups or ring residues:

2x12

24 nm

calculated: observed:

Base value: alkyl groups: Exocyclic double bond: calculated: observed:

249 nm 249 nm

Base value: five membered ring parent enone β-alkyl groups or ring residues: Exocyclic double bond: calculated: observed:

202 nm

2x12

24 nm

1x5

5 nm

231 nm 226 nm

214 nm 3x5

15 nm 5 nm

234 nm 235 nm

h) Base value: five membered ring parent enone α-Br β-alkyl groups or ring residues: Exocyclic double bond: calculated: observed:

202 nm

2x12

25 nm 24 nm

1x5

5 nm

256 nm 251 nm