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Organic Chemistry 326 SI
November 21, 2016
Review SN1, SN2, E1, E2
Quiz Due tonight
70-80% new material
Final Exam Review
SN1, SN2, E1, E1cb, E2
Alkyl Halide Type (SM)
Primary Alkyl Halide
Strong Bulky Non-nucleophilic Base
(Tert-butyl oxide, DBN, DBU)
Leaving group is two carbons away from carbonyl group
Secondary Alkyl Halide
Weakly Basic Nucleophile
Polar Protic Solvent or Polar Aprotic Solvent
Polar Protic Solvent
E2 preferred (SN2 does occur as minor product)
Weak Base and Nucleophile
SN1 and E1
Tertiary Alkyl Halide
SN1 and E1
What is(are) the product(s) of this reaction?
Which mechanism does this reaction prefer to undergo?
A and C
What is the product?
I (major) and III (minor)
All of these form
What mechanism does this reaction follow?
Is this reaction concerted?
After the ionization step, what forms?
None of these
Used to measure molecular weight, which can be used to determine the molecular formula
Radical cations form from the bombardment:
These decompose into fragments
Cations and radicals
Cations are the analyzed fragments
Fragments sorted by mass-to-charge (m/z) ratio
z is almost always +1
Therefore, the measurements are of the mass of the ions
When analyzing a spectrum, what is used to determine the molecular fingerprint?
Molecular ion peak (M peak) (AKA Parent peak)
M + 1 Peak
All of these are important
Detected fragments form peaks
Multiple peaks form from unstable molecular ion breaks down into fragments with lower molecular weight
Represents unfragmented cation radical
Equals Molecular Weight
Molecular ion or Parent ion (M+)
Most intense Peak – Highest concentration
Assigned 100% intensity
What is the m/z ratio of the parent ion?
What is the MW of the sample molecule?
Not enough information
Hydrocarbons and compounds containing only C, H, O have an even mass
Compounds with a odd number of N have an odd mass
If there is an even number, the mass is even…
M + 2 Peak
Chlorine (isotopes form at a 1:3 ratio)
Molecular ion consist of two peaks (M and M + 2) at a 3:1 ratio
35Cl correlates with the larger peak (M peak)
37Cl correlates with the smaller peak (M + 2 peak)
Bromine (isotopes form at a 1:1 ratio)
Molecular ion consist of two peaks (M and M + 2) at a 1:1 ratio
79Br and 81Br
What molecule has this spectrum?
What compound is this?
What molecule is this?
Which is which?
Options: methylcyclohexane and ethylcyclopentane
Options: 2-hexene and 2-methyl-2-pentene