ch 12 Flashcards
In mass spectrometry, the substance with a 1+ charge and a mass equal to the molar mass of an organic compound is called the
molecular ion
Identify the type of functional group that is most likely to give a fragment ion at m/z = M-18.
alcohols
In mass spectrometry, there are patterns in the molecular ion region due to isotopic abundances.
Identify the pattern that would correspond to a molecule containing one chlorine.
II
Energy of a photon is ______ proportional to frequency, and _______ proportional to wavelength.
directly, inversely
Which functional group might be present in a compound if it shows IR absorptions at 1715 cm⁻¹ and 2500-3100 cm⁻¹ (broad)?
carboxylic acid
In which region of the IR spectrum would a ketone give a very characteristic band?
2000-1500cm-1
Vibrational transitions in molecules typically require energies that correspond to the _________ region of the electromagnetic spectrum.
IR
examining the infrared spectrum of a compound allows us to determine what?
the types of functional groups present in a compound
What is the frequency of a peak that is most likely to correspond to a sp² C-H stretch of an alkene in an IR spectrum.
The sp² C-H stretch of an alkene typically appears between 3100-3000 cm⁻¹.
An IR spectrum of an unknown compound is shown below. Predict the primary structural feature present in this compound.
alkane
In mass spectrometry, the peak with the greatest relative abundance is called a
base peak
In mass spectrometry, there are patterns in the molecular ion region due to isotopic abundances.
Identify the pattern that would correspond to a molecule containing one bromine.
I
Identify the type of functional group that is most likely give a molecular ion having m/z = an odd number.
amines
max number of hydrogens equation
2n+2
if you have an EVEN number of carbons the minimum amount of hydrogens you can have is __
2
if you have an ODD number of carbons the minimum amount of hydrogens you can have is __
4
IHD formula (degrees of unsaturation)
An ODD M+ means …
there is an odd number of nitrogen
Chlorine
Bromine
The base peak is the ________ and most __________ fragment
tallest, stable
IR range for C=O
1700
IR range for -OH
3200-3600
IR range for C-O-C
1200
IR range for C=C
1650
IR range for C triple bond C
2150
IR range for C triple bond N
2250
IR range for a benzene
1450-1650
IR range for carboxylic acid
2500-3200
to do a mclaffery you must…
have a c double or triple bonded to an EN atom
