CHEM 3301

• c=o 


  • strong appearance
  • 1630-1750
• Aromatic (C=C)


  • medium appearance
  • 1450-1550
• C-O 


  • alcohol, esters, ether
  • 1050-1150
  • medium appearance
• C-H


  • alkane
  • sp3
  • variable
  • 2800-3000
  • usually 2900
• O-H (OH)


  • alcohol and phenol
  • 3200-3600
  • broad and strong appearance
  • "U" shape
• O-H (COOH)


  • broad and strong
  • 3200-3600
  • shark tooth shape
  • carboxylic acid
• C=O (COOH) 


  • strong
  • 1710-1780
• C=O (Esters) 


  • strong
  • 1730-1750
  • sp2
• C=O (ketones and aldehydes)

  • strong
  • 1680- 1750
• Single bond stretch 


  • 2500-4000
  • ex: OH, NH, SH
• Triple Bond Stretch

  • 2000-2500
  • C≡N, C≡C
• Double Bond Stretch


  • C=C, C=O
  • 1500-2000
• Single bond stretch 


  • 1000-1500
• Bending Modes 


  • 500-1500
• Alkane Stretch 


  • ~2900

  
• N-H 


  • amine or amides
  • 3300-3500
• O-H (alcohols) 


  
  

  • higher than 3600
• Alkane SP3 C-H stretch


  • below 3000
• Alkene SP2 (C-H)


  • between 3000-3100
• Alkyne SP C-H


  • 3300
• Amine shape 2H (2°)


  • NH

  A) 2 H's

  
• Amine shape (1°)

  • 2 Hydrogens

  A) ?

  
• C=O Ester 


  • 1730-1750
• C=O Aldehyde 


  • 1720- 1740
• C=O ketone 


  • 1710-1730
• C=O Amide 


  • 1630- 1690
• conjugation and absorption frequency

  • conjugation lowers the absorption
• IR VS UV vis

  • IR tells us possible FG in CM-1
  • UV tells us the level of conjugation nm
• Trends in λmax (UV vis )


  • the more conjugation the more stable, lower energy
  • Trend: the more conjugated, the greater the absorption length (nm)
  • less band gap space with conjugation
• IHD

  • 2n+2
  • subtract # of H and divide by 2
  • double bond = 1
  • triple bond = 2
  • ring = 1
  • Oxygen has no effect
  • nitrogen increases H by 1
  • halogens decrease H by 1
• ch 15. Base peak 


  • peak that hits 100% abundance

  
• M*+


  • heaviest mass charge (m/z)
  • overall mw

  
• 1:1 peak

  • Br
  • why?
  • M*+ and M+2 peaks almost same height
• 3:1 peak

  • Cl
  • M*+ and M+2 are significantly different in height
• NMR ch 17

  • NMR shows signal when you have an odd number of protons
  • even numbers are NMR silent
• Shielding 


  
  

  • the more en density the harder it is to spin flip
  • the closer it is to an EN atom the easier to spin flip
  • less shielding there is the higher the ppm (higher chemical shift)
  • ppm = chemical shift
  • the further you get from an EN atom the less shielded
• PPM in relation to shielding

  • the higher the PPM, the less shielding ( next to EN atom)
• chemical shift


  
  

  • closer en the higher the ppm
  • closer to EN the more deshielded
• ppm ~ 7


  -

  
• ppm ~ 9-10


  -