Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
22 Cards in this Set
- Front
- Back
|
3600-3200
|
O-H
Strong, Broad |
|
|
N-H
|
3500-3200
Medium |
|
|
C-H
Csp3 Csp2 Csp |
3000-2850
Strong 3150-3000 Medium 3300 Medium |
|
|
C=_C (triple bond)
|
2250
Medium |
|
|
C=_N (triple bond)
|
2250
Medium |
|
|
C=O
|
1800-1650 (often ~1700)
Strong |
|
|
C=C
|
1650
Medium |
|
|
Benzene
|
1600+1500
Medium |
|
|
If bonds are nonpolar (no net dipole), will they appear in an IR spectroscopy graph?
|
No; there must be a change in dipole moment during vibration for a bond to show up on IR.
|
|
|
What is the unique IR pattern of an amine? How does this differ from a nitrile?
|
An amine/amide will have 2 peaks, while a nitrile will have a sharp, medium triple bond peak.
Amides have very strong double peaks (beta to a carbonyl) Amines have short, double peaks when they are not adjacent to other polar molecules (like oxygen). |
|
|
What determines how peaks and splitting occurs in HNMR?
|
Not all protons absorb at the same frequency.
Protons in different electronic environments (in other words, have a different part to play in the geometry of the molecule) absorb at slightly different frequencies, so they are distinguishable by NMR. |
|
|
What does upfield/downfield mean?
|
Upfield means the proton reading is to the right of another proton reading.
Downfield means the proton reading is to the left (more deshielding). |
|
|
What does it mean for a proton to be more deshielded?
|
A proton is more deshielded when the adjacent carbon (or oxygen) has its electron density drawn away by adjacent electronic conditions.
|
|
|
Can protons bonded to the same carbon be in different electronic environments?
|
Yes; cyclic rings are a prime example, as well as hydrogens bound to the same alkene carbon.
|
|
|
HNMR ppm:
Csp3 RCH3 R2CH2 R3CH |
0.9-2
~0.9 ~1.3 ~1.7 |
|
|
HNMR ppm:
Proton allylic to a double bond Proton of a terminal alkyne Proton bonded to carbon bonded to electronegative atom |
1.5-2.5
~2.5 2.5-4 |
|
|
HNMR ppm:
Proton bonded to alkene Proton on benzene ring/aryl ring Proton on aldehyde Proton on a carboxylic acid substituent |
4.5-6
6.5-8 9-10 10-12 |
|
|
HNMR ppm:
Alcohol Amine |
1-5
1-5 |
|
|
CNMR ppm:
sp3 sp3 with electronegative atom alkyne |
5-45
30-80 65-100 |
|
|
CNMR ppm:
Alkene benzene C carbonyl |
100-140
120-150 160-210 |
|
|
CNMR ppm:
Csp2 of an arene |
120-150
|
|
|
HNMR ppm:
Benzylic H |
1.5-2.5 ppm (somewhat deshielded Csp3-H)
|
