Show how you would distinguish between the following by spectroscopy
Q.2. (b) Show how you would distinguish between the following by spectroscopy
(i) Aldehyde and Ketone
(ii) Alcohol and Ether
(iii) Mono substituted benzene and Di-substituted benzene
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(i). Aldehyde and Ketone
Highly polar C=O bond (1710 - 1720 cm-1) (present in both aldehydes & ketones)
C-H bond sp2 carbon (2700-2800 cm-1) (present only in aldehydes)
Figure 2.3 (butyraldehyde)
Figure 2.4 (2-heptanone)
(ii). Alcohol & Ether
IR spectra:
C—O bond 1050-1275 cm-1
1o ROH 1050
2o ROH 1100
3o ROH 1150
ethers 1060-1150
O—H bond 3200-3640 cm-1
(iii). Mono & Di-substituted benzene
IR spectra:
=C—H bond, “unsaturated” “aryl”
(sp2) 3000-3100 cm-1
+ 690-840
Mono-substituted + 690-710, 730-770
ortho-disubstituted + 735-770
meta-disubstituted + 690-710, 750-810(m)
para-disubstituted + 810-840(m)
C=C bond 1500, 1600 cm-1