Hi there! I really need help analyzing this please, I tried looking at the chart

Question

Hi there! I really need help analyzing this please, I tried looking at the chart for the wavenumber but always get it wrong. Your help is very much appreciated!

In this exercise, you are given IR spectra and in some cases MS spectra. For each unknown, annotate the spectrum/spectra showing all key absorptions and use them to identify the functional groups and the compound name. Be explicit, the list of possible unknowns is on the last page. Some compounds contain more than one functional group. While some of the spectra contain peaks that might fit with more than one of the choices, there is a best choice for each spectrum. You must pay attention to the details.

Choose from the following list of functional groups: amine, alcohol, alkene, alkyne, aldehyde, carboxylic acid, nitrile, ester, arene (aromatic), ether, and ketone.

You must have annotated spectra to receive any credit for the problem. The annotations must also support your choice of functional groups and compound. Since sp3 is common, C-H, stretching is not considered a functional group and these are not to be annotated. Do not try to assign every peak – just the ones necessary to pinpoint the functional groups. What functional group? what is the name of it? what is the structure? Do not forget to annotate.

L0D 5D 4000 3000 1000 500 HAVENUMBERI 11 Functional Group(s) Name Structure 100 MS-NW-1217 M+ 82 80- 60 0 40 0) 20- 50 60 70 80 90 10 20 30 40 m/z

Explanation / Answer

A. Functional group is alkyne as it has peaks at 3310 & 2120 cm-1 for triple bonded CH (sp for CH stretch) and carbon - carbon triple bond (sp - sp carbon).

And from mass spectrum, it has m/Z -82 which corresponds to 1-Hexyne.(terminal alkyne)

B. It is an aliphatic unsaturated ester as it has peaks at 3100, 1740, 1660 and 1170 for =CH, C=O, C=C and C-O stretches respectively in IR spectrum.

While from mass it has m/Z-114 3 equivalent to C6H10O2.

Expected Name : ethylbut-2-enoate (CH3CH=CHCOOCH2CH3)

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