File c GCMs Data\\JB37OLMjbhs2017 37OLVDA.D JBH operator Instrument 25 Apr 2017

Question

File c GCMs DataJB37OLMjbhs2017 37OLVDA.D JBH operator Instrument 25 Apr 2017 15:57 using AcqMethod 37OL UNKNOWN HIGH BP.M FRANK Misc Name: Info Vial Number 1 Abundance TIC: DADVdata.ms 1.8e+07 1.6e+07 1.4e +07 1.2e+07 le 07 8000000 6000000 4000000 2000000 Time 1.50 2.00 2.50 3.00 3.50 4.00 4,50 5.00 5.50 6.00 6.50 7,00 7.50 8.00 8.50 Abundance Average of 1.892 to 1.998 min.: DA.Didata.ms 700000 650000 600000 550000 500000 450000 400000 350000 300000 250000 200000 150000 100000 270 62 69 77 91 m10 8 126 138 mm 177 187 203 219 230 240 250 260 2 146 56 m 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 50000

Explanation / Answer

1) The mass spec shows two peaks, one at m/z 84 and the other at m/z 55. The peak at m/z 84 is the molecular ion peak. The peak at m/z 55 is a fragment. A look at a table of common mass fragments shows that a fragment at m/z 55 is due to C4H7 fragment. A loss of m/z (84 – 55) = 29 may correspond to C2H5 or CHO. The compound is most likely C4H7C2H5 ( that is C6H12) or C4H7CHO.

2) The IR peak shows a number of notable peaks. The most intense peak is at 1746 cm-1 and is most likely due to –CH=O group of aldehyde. The peaks at 2965 and 2884 cm-1 are the two bands due to =C-H group. The peaks at 834 and 959 cm-1 are possibly due to C-H bending vibrations of the alkene.

At this point, we strongly believe that the compound is an unsaturated aldehyde. The compound is most likely 3-methyl-but-2-ene-1-al.

The NMR spectra doesnt support this compound though; and the NMR peaks show little information; it leads us to an alkene which negates the IR. Kindly check.

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