Question

The following involves a question related to a spectrum of two samples. I am confused as to how I am supposed to take the H-NMR spectrum and determine the mass of the specified compound. Thanks

2) Shown below are two spectra of N-phenylbenzylamine in CDCl3. In spectrum B, 2.1 mg of p- dimethoxybenzene has been added to the sample. The resonances of p-dimethoxybenzene have chemical shifts of 6.9 and 3.8 ppm a) The peak integration represents area under the peaks. The peak areas indicate what type of ratio: mass, volume or mole? b) What is the mass of the N-phenylbenzylamine in the sample? 2.01 0.56 1.0x) 6.90 0.51 0.98 3.82 CHEM 4024/5024 page 2 of 5

Answer 1

(a) The peak integration represents area under the peaks The peak areas indicate molar ratio (b) Take any one of the two Either 6.9 or 3.8 (Both will give same result) Had it been only p - dimethony benzene in the solution, the peak integration for the protons should have been 4 But in the mixture of the two compounds the peak integration comes to be 0.26 so, the percentage amount of no on is - 0.26/(0.26 + 4) times 100 = 6.1 % so, the solution contains 6.1 % of with respect to Let the amount of be x so, x times 6.1/100 = 2.1 implies x = 2.1 times 100/6.1 = 34.42 mg