Choose a spectrum and click START!
Use the buttons in the frame on the left to answer the questions. Help will appear in this frame if you press the "?" button or choose the wrong answer. Repeat a question by pressing "<". Have fun!
To reverse the x-axis on the spectrum, scroll down in the top frame and click on "Reverse X". You can expand regions of the spectrum by dragging the mouse. Click on the spectrum to see the whole spectrum again.















Help for Aromatic
If aromatic you should see something in the following regions
C-H stretch 3080-3030 (often rather weak)
C=C stretch 1625-1580 and 1515-1450
C-H bend 910-670 (one or more bands depending on substitution)

Don't forget that other groups can give bands which sometime resemble aromatics
C-H stretch is similar to alkenes
C-H bend is similar to cis alkenes and C-Cl stretch
C=C stretch overlaps the nitro stretch, the N-H bend, and the CH2 and CH3 bend.
Is it aromatic?








You got the aromatic question Wrong
Either you misread frequencies or you mistook the bands for something else

If aromatic you should see something in the following regions
C-H stretch 3080-3030 (often rather weak)
C=C stretch 1625-1580 and 1515-1450
C-H bend 910-670 (one or more bands depending on substitution)

Dont forget that other groups can give bands which sometime resemble aromatics
C-H stretch is similar to alkenes
C-H bend is similar to cis alkenes and C-Cl stretch
C=C stretch overlaps the nitro stretch, the N-H bend, and the CH2 and CH3 bend.








Correct!




















Help for Subtypes:
The type of substitution can often be determined by analysis of the C-H bending bands.
The following has been observed for simple aromatics:
monosubstituted770-730 and 710-690
Di-ortho770-735
Di-meta900-860, 810-750, and 725-680
Di-para860-800
1,2,3-tri780-760, and 745-70
1,2,4-tri885-870, and 825-805
1,2,5-tri865-810 and 730-675
Tetrasubstituted and pentasubstituted derivatives give a weak band between 870 and 840, with the exception of the 1,2,3,4-tetra case, which is between 810 and 800. The overtones of these strong bands can also be useful
The region of interest is 2000-1667.
CAUTION
Alkene bendings and C-Cl stretch can interfere with analysis of the 910-670 region
The overtone region can be obscured by a carbonyl or by unrelated overtones








You got the subtype question wrong.
The type of substitution can often be determined by analysis of the C-H bending bands

The following has been observed for simple aromatics:
monosubstituted770-730 and 710-690
Di-ortho770-735
Di-meta900-860, 810-750, and 725-680
Di-para860-800
1,2,3-tri780-760, and 745-70
1,2,4-tri885-870, and 825-805
1,2,5-tri865-810 and 730-675
Tetrasubstituted and pentasubstituted derivatives give a weak band between 870 and 840, with the exception of the 1,2,3,4-tetra case, which is between 810 and 800.
The overtones of these strong bands can also be useful, the region of interest is 2000-1667.
CAUTION
Alkene bendings and C-Cl stretch CAN interfere with analysis of the 910-670 region the overtone region can be obscured by a carbonyl or by unrelated overtones the actual substituent type is 1

Now we try to identify substituents;
first those containing carbon and hydrogen









That's Right!





















Help for Alkyne:
Monoalkynes show C-H stretch at 3310-3200(M-S), and C-C stretch at 2140-2100(M).
Disub alkynes show weak C-C STR at 2260-2190(W)
CAUTION-alcohol OH stretch can overlap with alkyne C-H stretch.
Also:
Misc overtones will sometimes appear in the C-C stretch region the stronger nitrile and isocyanate stretchings are nearby.











You got the Alkyne Question Wrong:
Either you misread frequencies or you mistook the bands for something else.








Yes, Good!





















Help for Alkene:
Alkenes show C-H stretch at 3100-3010(M), C=C stretch at 1680-1640 (W-M), and CH bend at 1000-666(S)
The 1000-666 bend can show one or more bands, depending on the type of alkene
Remember that other groups interfere.
Aromatics show similar C-H stretch.
The C-H bend overlaps with that of some aromatics and with the C-Cl stretch.
Here is some more info about alkenes:
The C=C stretch becomes more intense when conjugated with carbonyl
The C-H bend is a good diagnostic for alkene type
Mono-substituted 995-985(S) and 910-905(S)
Disub-gem 895-885(S)
Disub-trans 980-965(S)
Disub-cis 730-665(S)(here you may see two bands)













Correct!





















Help for Saturated Carbon:
Saturated alkyl groups show C-H stretch bands between 2965 and 2850(M-S) and C-H bend bands between 1485 and 1355(M-S)

Here is some more info about saturated alkyl:
Methyl CH stretch 2972-2952(S) and 2882-2862(S)
Methyl bend 1470-1430(M) and 1380-1370(M-S)
Both are shifted approx 25 lower when methyl is bonded to carbonyl.
Methylene C-H stretch 2931-2921(S) and 2858-2848(S)
Methylene bend 1480-1450(M), shifted 40 lower when bonded to carbonyl.
The methyl bend at 1380-1370 is split into a rather symmetrical doublet when a gem-dimethyl is present. If a t-butyl group is present, this band is split into an unsymmetrical doublet, with the low-frequency line more intense.
Unrelated methyls in the molecule will obscure these.








Very good!





















Help for Geminal-dimethyl and t-Butyl:
The methyl bend at 1380-1370 is split into a rather symmetrical doublet when a gem-dimethyl is present. If a t-butyl group is present, this band is split into an unsymmetrical doublet, with the low-frequency line more intense.
Unrelated methyls in the molecule will obscure these.

















You got the Geminal-dimethyl question wrong:
Look for the symmetrical doublet at 1380-1370. This doublet can be quite small and can be obscured by other peaks. Spectral noise and nearby peaks can also distort the intensities, so the peaks don't look symmetrical.

















Yes, good going!




















You got the tert-butyl question wrong:
Look for the unsymmetrical doublet at 1380-1370. This doublet can be quite small and can be obscured by other peaks.

















Yes, excellent!




















Help for -CH2CH2CH2CH2-
Four or more consecutive methylene groups give a peak at 710-730. This peak is the concerted rocking of all four -CH2- groups.

















You got the -CH2CH2CH2CH2- question wrong:
Look for the small peak at 710-730. This peak can be quite small and can be obscured by other peaks. Sometimes it can be hard to find.

















You bet!




















Help for S-H
The S-H stretch is seen at 2600- 2550(W)















You got the S-H question Wrong!
Either you misread your frequencies or you are confusing other bands which happen to be in the area.














Yes!





















Help for P-H
The P-H stretch is seen at 2425- 2325(M)
















Yes!




















Help for Nitrile
Nitrile stretch is seen at 2260- 2220(M)



















You got the Nitrile question Wrong:
Either you misread your frequencies or you are confusing other bands which happen to be in the area

The isocyanate has a strong band nearby.











Very Good!





















Help for Isocyantes:
Isocyanates are seen at 2275-2240(S), Thiocyanates are seen at 2175- 2140(S).






















Yes!





















Help for Carbonyl:
Carbonyl compounds show strong absorptions between 1850 and 1640.
Not to be confused with W-M C=C stretch or misc overtones.




















Excellent!





















Help for Carbonyl Subtypes:
Carbonyl frequencies are useful:
Saturated Aliphatic
Functional
Group
5-member ring6-member ring
and acyclic
Aromatic
Aldehyde 1725-17151715-1695
Ketone1750-17401725-17051700-1680
Diaryl Ketone  1670-1660
Acid(dimeric) 1720-17101700-1680
Ester177017351725-1715
Amide 1690-16401705-1655
Anhydride1875-1855
& 1795-1775
1830-1790
& 1770-1740
1795-1775
& 1735-1715
Acid Chloride 1810-17901780-1750

1. Esters are confirmed by analysis of strong C-O bands:
Alkyl Acetates1250-1235& usually 1110-1030
Vinyl and Phenyl Acetates1220-1205
Higher aliphatic esters1205-1160
Esters of Aromatic Acids1300-1250 & 1150-1100
CAUTION: Ketones also give a M-S, sharp peak near 1200. However, the ester peaks in this vicinity are stronger and not so sharp.
2. Acids give OH stretch at 3300-2500(S-broad) & OH bend at 950-870(M-broad).
3. Aldehydes usually give two W-M, sharp C-H stretches near 2850 and at 2750-2720. The latter can be distinguished from alkyl chains, which don't usually extend to such low frequencies.




















You got the carbonyl type question Wrong:
Either you misread your frequencies or you are confusing other bands which happen to be in the area

Use the C-O region from 1300-1030. C-O absorptions are usually strong and broader than other peaks in the fingerprint region.











Good going!





















Help for Alcohols:
The OH str is a sharp weak peak at 3650-3600 in dilute solution
With moderate concentrations it appears as a sharp, weak peak at 3600-3500 and a strong broad peak at 3400-3200. If neat, you only see the broad band at 3400-3200.
The C-O str in alcohols and phenols gives a broad, strong band between 1260 and 1000.
   CHAIN TYPE
Type Straight Branched
Primary 1090-10501050-1000
Secondary1120-10901050-1000
Tertiary 1200-1100
Phenol 1260-1200











Correct!





















Help for Amine:
The NH2 stretch gives sharp, weak peaks at 3550-3420 and 3450-3320 in dilute solution. The NH stretch is at 3450-3310(W) if concentrated, both show stronger, often complex bands between 3300 and 3000.

NH2 bend is at 1650-1560(M-S), NH bend is 1600-1490(W)

These bands will overlap with aromatic ring stretchings.











You got the Amine question wrong!
Either you misread your frequencies or you are confusing other bands which happen to be in the area.


















Got that right!





















Help for Ethers:
Aliphatic ethers show a strong band at 1150-1070
Aromatic ethers show 2 bands, 1275-1200 and 1075-1020.
CAUTION, these will be obscured by such as alcohols and acids.











Yes, correct!





















Help for Nitro:
Aliphatic nitro shows bands near 1560 and 1350
Aromatic nitro is at about 1515 and 1350. All are strong.



















You got the Nitro question wrong:
Either you misread your frequencies or you are confusing other bands which happen to be in the area











Good!





















Help for S=O:
Here are some S=O frequencies, all are strong
Sulfoxide 1060-1040
Sulfone 1340-1300 and 1160-1135
Sulfonate 1420-1330 and 1200-1145
Sulfonamide 1370-1330 and 1180-1160












You got the S=O question wrong!
Either you misread your frequencies or you are confusing other bands which happen to be in the area.

















Very Good!





















Help for Halogen:
Compounds having one F show 1250-960, with several F, you will see several bands between 1425 and 800.
C-Cl STR is strong at 845-500, C-Br and C-I absorb below 667.












You got the Halogen question wrong!
Either you misread your frequencies or you are confusing other bands which happen to be in the area. Halogens are difficult to find using IR. However, you should suspect that halogens might be present if you haven't found anything else.

This is the end!
You have reached the end of the program! -> Review the printout, and propose 1 or 2 structures for the unknown.















Very Good!

This is the end!
You have reached the end of the program!
-> Review the functional groups, and propose 1 or 2 structures for the unknown.

Colby Chemistry