Question

I need help with my chem lab report.

I need to identify the unknown structure.

Please help me identify the importance of each peak in the spectrums.

What would the reactions look like for this structure when it reacts with ethanol for DNPH test, CrO3 and dioxane and NaOH for iodoform test.

The compound was a clear liquid. It is insoluble in water. tests positive for DNPH test, positive for CrO3 test and negative for iodoform. These results tell me that the compound is non polar, is an aldehyde with no methyl ketone.

This unknown is insoluble in water so it is non polar. What does this tell me about the structure?

Thank you !!

Transmittance [%] 50 60 70 80 30 40 90 100 BRUKER 3500 3000 3033.06 2921.91 me 2824.72 2732.72 2500 Wavenumber cm-1 2000 1685.52 1603.00 1576.28 1500 1387.02 1306.41 1207.51 1167.08 1000 845,87 806.20 756.56

Answer 1

From mass spectra

mol weight of compound = 120 g/mol

chemical tests

positive DNPH test shows -aldehyde or ketone may present

Negative iodoform suggests that no -COCH3 group is present

CrO3 test positive suggest That compound is aldehyde or primary or secondry alcohol

putting all chemical test together indicates that compound is ALDEHYDE

proton nmr

peak at 9.8 ppm corresponds to -CHO proton

peak at 2.4 ppm confirms Ar-CH3 proton

symmetric doublets in aromatic region (7.3 and 7.8 ppm) suggests para substitution.

Expected compound is 4-methylbenzaldehyde

IR Spectra

2824 cm-1 suggests aldehydic C-H

2931 cm-1 suggests C-H of CH3

3033 cm-1 aromatic C-H

1685 cm-1 aromatic aldehyde

all data suggests 4-methylbenzaldehyde is the compound in question