Question

can someone tell me wjat this is the IR of my product means this is a lab where we produced 1,4-diphenyl-1,3-butadiene from benzyltriphenylphosphonium chloride and trans-cinnamaledyde using sodium hydroxide as the base

TVV 129535 10735102770 1870.22 Outsvors 102487078 737 05 Webes cm.) d n sh United States Focus MacBook Air

Answer 1

The above-mentioned IR spectra is of the compound 1,4-diphenyl-1,3-butadiene. The structure of 1,4-diphenyl-1,3-butadiene is

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So the compound 1,4-diphenyl-1,3-butadiene contains Alkenyl C-H ( =C-H) and aromatic C-H bond. The stretching frequency of these kinds of C-H appears between 3100 cm-1 to 3000 cm-1 with the signal intensity being weak in nature. So signals appearing at 3054.37 cm-1 and 3015.17 cm-1 are due to these ( =C-H) and aromatic C-H bond stretching.

Now there are aromatic C=C and alkenyl C=C bonds in the compound. The stretching frequency of aromatic C=C appears at 1600 cm-1 to 1400 cm-1 region and for alkenyl C=C bonds the stretching frequency falls at 1680 cm-1 to 1600 cm-1 region. So the peaks appearing at 1443.02 cm-1, 1489.54 cm-1, 1570.71 cm-1, and 1592.96 cm-1 are due to aromatic C=C and alkenyl C=C bonds stretching.

The aromatic C-H bending appears in the 2000-1650 cm-1 region. So the peaks at 1953.46 cm-1 and 1870.22 cm-1 are due to the C-H bending of aromatic C-H bonds that are present in the compound. The C-H bending of alkene appears in the 1000 cm-1 to 675 cm-1 regions. So the peaks appearing in this region are due to the bending of the alkenyl C-H present in the compound.

As there is no peak at around 2950 cm-1 to 2850 cm-1 regions which correspond to the characteristic C-H stretching of alkyl C-H, so the starting material benzyltriphenylphosphonium chloride is not left. And also there is no peak at around 1740 cm-1 to 1720 cm-1 regions which correspond to the characteristic aldehydic C=O stretching, so no trans-cinnamaldehyde is left in the reaction mixture.