Solved Problem Analysis: Below is an IR & MS analysis for 1-chloro-2methyl-2-phe

Question

Solved Problem Analysis: Below is an IR & MS analysis for 1-chloro-2methyl-2-phenylpropane. Read the analyses then critique the presented solutions. Determine if the solutions are correct or not. Write a paragraph on how you would convey the same information (include corrections or suggestions to improve the analysis presented). Analysis: The IR spectrum shows a large bundle of signals around 3000 cm^-1 which corresponds to the C-H stretches. The aromatic overtones are the medium-strong signals from 1450-1500 cm^-1. The CH_2Cl peak is around 1300 cm^-1 and has a medium absorption. The cluster of signals from 700-800 cm^-1 is due to the aliphatic C-Cl absorptions. Analysis: The mass spectrum shows the molecular ion (M^+) at 168 m/z and the M + 2 ion at 170 m/z. The M + 2 ion is present because chlorine has 2 isotopes in almost equal abundance (^34Cl and^36Cl). There are two other predominant peaks in the spectrum: one at 119 m/z and one at 91 m/z. The peak at 119 m/z correspo

Explanation / Answer

The analysis is right.

From the IR spectra it is clear that it has C-X bond. But from the mass spectra it is clear that the halogen present is Chlorine. If it had to be other halogen, the isotopic pattern would have been different. Therefore, we are clear about three important facts, There exists an aromatic ring and a C-X bond. Apart from this, i.e. 168- (77+35.5) = 55.5. Hence, we will have to be acountable for 55.5 m/z mass. As the mass spectrum also has a peak at 119 which correspond to PhC(CH3)2 and (CH3)2CCH2Cl, the structure must the same as that of the one given above

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