Mass spec & IR Flashcards
What is the most important feature of the mass spectra for alkyl chlorides and alkyl bromides?
The presence of the M+2 peak
Where does the M+2 peak in alkyl bromides/chlorides come from?
They are both present in nature in two isotropic forms each have a significant natural abundance
What are the two prominent isotope values for bromine?
79
81
What are the two prominent isotope values for chlorine?
35
37
What is the equation to work out the frequency of vibration?
frequency of vibration = 1 / 2πc √K/μ
Where is cyano functional group found on IR spectrum?
Easy to spot
2260 - 2240
Why is the O-H stretch easy to find?
Peak often broad
Around 3500
Are C-H stretches easy to spot?
Yes
Around 3000
Where abouts is the stretch for the sp2 C-H (alkene)?
Occurs at values >3000
Where does the c=c stretching frequency occur?
Between 1670 and 1640 for simple non-cyclic alkenes
What happens to the C=C stretching frequency when alkyl groups are added?
Increases
What happens to the C=C stretching frequency if there is conjugation with carbonyl or other double bond?
Lowers
What is the effect of ring strain on the C=C stretching frequency?
The higher the ring strain, eg. Square, the lower the frequency value
Where is the hydrogen bonded OH broad at?
3400-3300
How many bands do primary amines show and where?
2
3500-3300
