Spectroscopy:

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Today
Conclusion Unknown 2/ Introduction Unknown
3 Nitro compounds. Inert Compounds.
Spectroscopy UV spectra MiniQuiz
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Nitro Compounds

• Preliminary tests?
• Solubility
• Classification tests
• Derivatives
• Spectra

Typical properties?
Classification test
Iron (II) Hydroxide Test for Nitro Groups Nitro
Compounds                                         
                                                  
                                                  
                                  
Always do with a known compound to compare!
Derivatives (if no other functional group
available) Reduce to amine and then prepare
amine derivatives
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Carboxylic Acids

• Preliminary tests?
• Solubility
• Classification tests
• Derivatives
• Spectra

IR
OH in gas phase (non-H-bonded)
H-NMR
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Amines
IR
Voodoo Lily
H-NMR
Amorphophallus
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Amides

• Preliminary tests?
• Solubility
• Classification tests
• Derivatives
• Spectra

IR?
H-NMR
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Unknown 3can be anythingAny of the
functional groups of unknowns 1 and 2also
Inert compounds
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Inert Compounds
Alkanes Aromatic Hydrocarbons Alkyl halides. Aryl
halides. Chemical tests and derivatives depend
on compound.

• Beilstein test (p.626) for Cl, Br Compare with
  known compound!

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UV/Visible Spectrophotometry

• Range of UV in nm?
• Which compounds generally absorb in the UV?
  CH4? CH3(CH2)10CH3? Ethanol?
  Benzene? Naphtalene? ?-Carotene? FeCl3?
• Which compounds absorb in the visible range?
• CH4? CH3(CH2)10CH3? Ethanol?
  Benzene? Naphtalene? ?-Carotene? FeCl3?

• See Chapter in your Lecture text (conjugated
  systems)
• to p HOMO to LUMO
• A e x C x l
• A absorbance e molar absorptivity
• C concentration in mol/L l sample pathlength
  in cm

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UV/Visible Spectrophotometry
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lmax
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• Next time
• Infrared spectrophotometry (IR)
• MiniQuiz on todays class