Given the IR of an alcohol (unknown), IR of the product (ester) and the HNMR of
ID: 498211 • Letter: G
Question
Given the IR of an alcohol (unknown), IR of the product (ester) and the HNMR of the ester. Determine the alcohol structure and name. This was a reaction that occurred when the alcohol was put with 7 ml of glacial acetid acid and 1 ml of sulfuric acid. PLEASE HELP ASAP! THANK YOU!
alcoh of i (g) of a s (g) inciple Grt ses Peaks chemi triplet 41 Wave number [cm-11 Model Name FTAR- 100typeA 2. P Serial Number B086361016 a. W [Data informationj Date 3/14/2017 3:57 PM Data array type Linear data array Wavenumber (cm-11 Auto (7.1 mm) 599,753 cm-1 Auto (30000 Hz) 4000.6 cm-1 Data pitch 0.964233 cm-1 Data pointsExplanation / Answer
In presence of conc H2SO4,
ROH +CH3COOH <===> CH3COOR + H2O
Your IR spectrums show the formation of ester with appearance of C=O stretch at ca. 1800 cm-1 which was absent in the spectrum of alcohol. Unfortunately, the IR spectrum does not reveal much.
The 1H NMR spectrum shows that the sample used was highly concentrated. This is evident by comparing the integral of CDCl3 peak (7.26 ppm) and the two giant peaks at 2.0 and 1.0 ppm.
Looking at the structure we know that the ester will show a singlet arising from CH3 directly attached to the carbonyl carbon. Comparing these giant peaks, peak at 2.0 ppm is a singlet while the one at 1.0 ppm seems to be a multipet. This suggests that the peak at 2.0 ppm must arise from CH3 and will have an integral of 3. These two peaks are in the ratio of 35:61 or 3:5. So the multiplet at 1.0 ppm arises from 5 protons and must be from CH3CH2 group.
The peak at 1.5 ppm seems to be water of esterification. Please note that other peaks have very small integral values compared to the peaks at 1.0, 1.5 and 2.0 ppm. This suggests that the product contains impurities and these peaks can be ignored.
The ester formed is CH3COOCH2CH3 or ethyl acetate and the alcohol used was CH3CH2OH or ethanol.
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