cyclopentanol Na,Cr,O, H,SO,

Propanoic acid and methyl ethanoate are constitutional isomers. (c) оооо (d) CH3 оооо CH₂ OH Show how to distinguish between them by IR spectroscopy. (Use the Appendix.) (a) Which IR bands would one expect for propanoic acid? propanoic acid оооо 1200-1250 cm 1375 1450 cm 1450 1475 cm 1630-1820 cm -1 1200-1250 cm 1375 1450 cm 1450-1475 cm 1630-1820 cm 1375 1450 cm -1 -1 -1 -1 1200-1250 cm (b) Which IR bands would one expect for methyl ethanoate? -1 -1 1450 1475 cm -1 -1 1630-1820 cm -1 00000000 −1 CH₂-C 0000 methyl ethanoate If the IR spectrum shows a band at 1780 cm-¹, which isomer is it? 1700-1725 cm 1735-1800 cm 2720 cm -1 2500-3300 cm 2720 cm Which IR bands are unique to, i.e. not shared between, the two sets? -1 1700 1725 cm 2500-3300 cm -1 CH3 1735-1800 cm -1 -1 -1 2720 cm -1 2500-3300 cm -1 1700-1725 cm -1 1735-1800 cm -1 -1 -1

Select the partial structure for a doublet integrating to 2H at 2.3 ppm. O=C-CH2-CH O-CH2-CH2 OC=C-CH₂-CH2 C-CH₂=CH

(a) (c) 12.4 Which IR spectrum is consistent with an alkene? 100 100 80 80 60 60 40 40- 20 20 1500 1000 2000 2500 Wavenumber (cm¹) 2000 2500 Wavenumber (cm¹) % Transmittance 0. 4000 100 % Transmittance 80- 60 40- 20. 0. 4000 3500 3500 3000 3000 1500 1000 (b) (d) % Transmittance % Transmittance 0 4000 100 80 60- 40- 20 0. 4000 3500 3500 3000 3000 mm y 1500 2500 2000 Wavenumber (cm¹) 2000 2500 Wavenumber (cm) 1500 1000 1000