IR Flashcards
(15 cards)
No. of carbon
100/1.1 (A. of M+1/A. of M)
[A=abundance]
Ratio of isotopes of chlorine in chloroalkane and dichloroalkane
3:1
9:6:1
Ratio of isotopes of bromine in bromoalkane and dibromoalkane
1:1
1:2:1
Isotope halogen masses in haloalkane and diholoalkane
m:m+2
M:M+2:M+4, where M=m+m
What is the expected abundance of H•, •CH and •CH3 radicals detected by the ir mass spectrometry?
0; only detect ions
Molecules will certainly break up when shot with electrons in ir mass spectroscopy. Yes or No and why?
No. C2H6, when shot can either
- ONLY get one electron removed, giving a radical cation
- BREAK up into two smaller compounds, 1 is cation and another is radical (not detected)
How to know the molecular mass through ir mass spectroscopy?
The peak with heaviest mass is the molecular mass (IF C is assumed to be one isotope)
How to tell a mass spectroscopy is showing carboxyl?
There is a peak on the mass that is 28 unit less than molecular due to CO breaking off from the original molecule
Does the peak in ir mass spectroscopy tell you anything otherthan abundance? Can you find something other than Mr of an element?
No.
Ir spectroscopy of organic compound for O-H in carboxylic acid is characteristics of…
(Refer data booklet)
Broad peak with only a little distinction with the neighbouring C-H peak
Ir spectroscopy of organic compound for O-H in alcohol is characteristics of…
(Refer data booklet)
Narrow peak with obvious distinction with the neighbouring C-H peak
Ir spectroscopy of organic compound for CN in nitrile is characteristics of…
VERY NARROW AND SHARP peak in its range
Ir spectroscopy with peak engulfing C-H indicates
hydroxyethanoic acid
Both C=O AND CN shows up as narrow peaks. how to differentiate?
CN is seen closer to the left (above 2000 cm-1)
How to write eqn to show the breaking of molecule in an ir mass spectroscopy?
[C4H6O]•+ → C3H3O+ + •CH3
REJECT
C4H6O → C3H3O+ + •CH3
