Term
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Definition
measures molecular vibrations which can be seen as
bond stretching/bending/combos of vibrational modes |
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Term
IR range in the unit of (cm-1)
max to min |
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Definition
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Term
| give max to min of fingerprint region |
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Definition
1500-400
(wont be tested but still good to know) |
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Term
given these frequencies :
2,800& 1,200
match to:
C-H
C-C
why? (explain the trend) |
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Definition
C-H: 2,800
C-C: 1,200
H bonded to any atom will have a higher frequency.
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Term
given these frequencies :
1,645 & 1,200
match to:
C=C
C-C
why? (explain the trend) |
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Definition
C=C: 1,645
C-C: 1,200
as we add more bonds between carbon atoms the frequency increases. |
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Term
given these frequencies :
3,080& 1645
match to:
=C-H
C=C
why? (explain the trend) |
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Definition
=C-H:3,080
C=C: 1645
remeber any atom bonded to H will have the larger frequency |
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Term
given these frequencies :
2,200& 3300
match to:
C=C
= C-H
why? (explain the trend) |
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Definition
C=C: 2,200
= C-H: 3300
again the H |
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Term
Which compound would have the lower frequency in an IR spectrum:
carbonyl vs a carbonyl in conjugation with double bonds? |
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Definition
| a carbonyl in conjugation with double bonds b/c the delocization of the pi electrons causes the C=O bond to lose double bond character, causing to absorb near C-O frequencies (1,000-1250) |
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Term
give the peak for alcohol
is it (sharp/broad)? |
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Definition
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Term
| compare the frequency of an ether vs alcohol |
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Definition
(OH) alcohol: 3300
(ROR) ether: 1050
remember H = higher frequency |
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Term
| what is the frequency for the C=O (carbonyl bond) |
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Definition
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Term
using 1750 as a base : who will have a frequency above this value and at this value?
aldehyde vs ketone |
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Definition
Above 1750: aldehyde (2,700)
H-C=O
has a Hydrogen & 1 R grp |
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Term
give an estimate IR peak for:
ketone
carboxylix acid (2) |
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Definition
ketone: 1700-1750 (carbonyl)
c. acid will have 2 peaks: 1700-1750 (carbonyl)
& 3300 (alcohol) |
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Term
give IR peak for amine
(how does it differ from alcohol) |
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Definition
3100- 3500
(same range as alcohol BUT has a sharp peak) |
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Term
| Will Br2 have show up on an IR? |
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Definition
no, for a compound to a frequency it must experience a dipole moment
(aka an atom is attached to an electronegative atom.)
Br2 is symmetrical (and CCl4) and cant be detected by IR. |
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Term
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Definition
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Term
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Definition
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Term
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Definition
this bond is too weak for IR (
C2 just like Br2 does not have dipole moment) |
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