# Which one is the correct molecule of the given properties of IR Spectroscopy?

1. $$\ce{CH3CH=CHCO2CH3}$$
2. $$\ce{CH3COOCH=CHCH3}$$

$$\pu{2950 cm-1}, \ \pu{2870 cm-1}, \ \pu{1740 cm-1}$$ are the observed peaks.

No peaks observed $$\pu{1700-1500 cm-1}$$.

The formula of the molecule is $$\ce{C5H8O2}$$.

My pre-answer is the first option. Because $$\pu{1500-1700 cm-1}$$ includes unsaturated carbons.

• Does not correspond to the literature spectrum for 1 chemicalbook.com/SpectrumEN_623-43-8_IR1.htm – Waylander Apr 20 '20 at 12:58
• So, the first one is wrong. And, the answer is 2. Nothing else?@Waylander – Yeliz Gülsün Apr 20 '20 at 13:59
• I'm not a fan of IR as a diagnostic for structural determination, and have not used it much for the last 30 years. NMR is much stronger. – Waylander Apr 20 '20 at 14:28
• Thanks for your comments. My professor is awaiting replies from me.@Waylander – Yeliz Gülsün Apr 20 '20 at 14:49
• 1740 is a bit low for the carbonyl of a vinyl ester according to my old copy of Williams & Fleming but it could be that signal – Waylander Apr 20 '20 at 15:08