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Problem 5

Formula: C4H8O2

Spectroscopy Reference

IR spectrum NMR spectrum

Rule 2, omit O, gives C4H8
4 - 8/2 + 1 = 1 degree of unsaturation.
Look for 1 pi bond or aliphatic ring.

The band at 1743 indicates a carbonyl, probably a saturated aliphatic ester. The bands at 3000-2850 indicate C-H alkane stretches. The bands in the region 1320-1000 could be due to C-O stretch, consistent with an ester.

Structure answer

This is the structure. See if you can assign the peaks on your own.

NMR answer

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