Question

Given the HNMR and the IR spectra, which of the four compounds above could it be? make sure that your limiting reagent and percent yield calculations are presented.

DMAD (dimethyl acetylenedicarboxylate) DEAD (diethyl acetylenedicarboxylate) DPAD (dipropyl acetylenedicarboxylate) DIAD (diisopropyl acetylenedicarboxylate) What is the final product? Is this DMAD, DEAD, DPAD, or DIAD? Initial volume of dienophile: 1.5 mL Initial volume of cyclopentadiene: 2.0 mL Final weight of Diels-Alder product: 1.296g Time spent boiling off Starting material: 12 minutes 800 600 500 300 200 100 8.0 7.5 7.0 6.5 6.o s.5 5.0 4.5 4,0(pp3.5 3.0 2.5 2.0 1.5 1.00.50.0-os fi (ppm DMAD (dimethyl acetylenedicarboxylate) DEAD (diethyl acetylenedicarboxylate) DPAD (dipropyl acetylenedicarboxylate) DIAD (diisopropyl acetylenedicarboxylate)

Answer 1

Answer: DPAD

It is clear that DMAD will show only one signal for methyl protons -CH3

DEAD can show two signals one triplet (-CH3) & one quartet (-CH2-)

DPAD will show 3 signals one triplet (-CH3), one sextet (middle -CH2-), and one more triplet (end -CH2)

DIAD also shows two signals only - one septet (-CH-), and one doublet (two -CH3)

DPAD: IR analysis:

alkyl C-H stretching 2850-3000 cm-1 region

alkyl C-H bending 1350-1480 cm-1

absence of peak in the region 2100-2260 cm-1 confirms that given alkyne is symmetrical

strong signal in the region 1735-1750 cm-1 due to ester C=O str

two more bands in the region 1000-1300 cm-1 are due to C-O stretch

DPAD 1H NMR analysis:

4.2 ppm, triplet, 4H, -CH2-O-CO-

1.7 ppm, triplet of quartet, 4H, middle -CH2-

0.9 ppm, triplet, 6H, -CH3

Simulated 1H NMR spectrum has been attached below for you!

·r ﹃[ Chemical structure with hydrogen exploded ? | | List of signals Drop or paste a jcamp file ssignm.. Delta N.. Mult J(Hz) 18,17,18.. 0.902 8 t 4,15,23 1,7014 toq 19,20,21.. 4.1884t Paste or drop a molfile or SMILES 8.99 7.120.89 7.12 Click to superimpose Nud. Solv... Exp.File HNMR: 00.90 (6H, t, J 6.9 Hz), 1.76 (4H, tq. J7.1, 6.9 Hz), 4.17 (4H,t, J 7.1 Hz). 1H NMR spectra Double click to zoom out, SHIFT+ double click to zoom out by step, SHIFT+drag to move spectrum 2.46 ppm 6.0 Simulate spectrum Advanced options Frequenoy: 400 Line wridth Download all

make sure that your limiting reagent and percent yield calculations are presented.

Without complete reaction scheme and data table it is impossible for me to do that.

Hope this helped you!

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