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spectroscopy spectrometry proton nmr carbon 13 ir infrared mass organic chemistry CHM 325
CHM 325 Organic Chemistry
In Ultraviolet-Visible(UV-Vis) spectroscopy, a molecule is treated with ultraviolet-visible light to excite and electron and causes _____ (the molecular effect)
In infrared spectroscopy, absorption of infrared light by a molecule causes _____ (molecular effect)
In nuclear magnetic resonance spectroscopy, absorption of radio frequency by a molecule causes _____ (molecular effect)
nuclear spin transition
Which spectroscopy causes electronic transition?
Which spectroscopy causes molecular vibration?
Which spectroscopy causes nuclear spin transition?
Nuclear magnetic resonance spectroscopy
What light is used in infrared spectroscopy?
What light is used in nuclear magnetic resonance spectroscopy?
What happens in mass spectrometry?
A molecule is ionized and broken apart into more ions (fragments).
How do you calculate element of unsaturation?
What is 1 element of unsaturation?
What is 2?
[2(number of C + 0.5 number of N)+2-(number of H + number of halogens)]/2
1 = ring or double bond
2 = triple bond
IR spectrum: Why are peaks broad for O-H and N-H?
Hydrogen bonding allows for different enviornments (ex: variances in strength of H bond vibrations, dimerization) and causes the molecules to absorb different lights.
Why are absorptions of C=O for amides lower than other C=O bonds?
Amides don't have a full C=O bond due to resonance structures so we see a lower rate number.
IR spectrum: How does conjugation effect absorbance?
Conjugation is when multiple bonds can alternate into single bonds (resonance structures). Conjugated molecules do not have full C=O bonds so they have lower rate number.
Mass spectrometry: What is M
Found at mass of the molecular ion on the spectrum
Mass spectrometry: How do you identify Cl?
+2 is a third of M
Mass spectrometry: How do you identify Br?
+2 is as large as M
Mass spectrometry: How do you identify S?
+2 is larger than 4% of M
peak (not as clear as Br or Cl)
Mass spectrometry: How do you identify I?
Peak at 127 or fregment that is M
Mass spectrometry: How do you identify a loss of an alcohol?
A peak at M
NMR: Absorption on the left of the spectrum is referred to as _____
Downfield or deshielded
NMR: Absorption on the right of the spectrum is referred to as _____
Upfield or shielded
What is TMS and what is its structure?
H NMR: What is the ppm of H next to a saturated center?
H NMR: What is the ppm of H next to an unsaturated center or an acetylenic H?
What is acetylene?
(red is acetylenic hydrogen)
H NMR: What is the ppm of H next to a highly electronegative atom (O, N, halides)?
H NMR: What is the ppm of a vinylic H (C=C-H)?
H NMR: What is the ppm of an aromatic H?
H NMR: What is the ppm of an aldehyde H (O=C-H)?
H NMR: What is the ppm of a carboxylic acid proton (O=C-O-H)?
H NMR: What is the n+1 rule?
The number of splits is number of H on the adjacent center causing splitting (n) + 1
C NMR: What is the ppm of a Csp
C NMR: What is the ppm of a Csp
C NMR: What is the ppm of a C=O of amide/ester/carboxylic acid?
C NMR: What is the ppm of a C=O of ketone/aldehyde?
C NMR: What is the ppm of sp hybridized C?