From the following HNMR spectrum of the compound C4H7N. It is interpetable as a

Question

From the following HNMR spectrum of the compound C4H7N. It is interpetable as a firs-order spectrum, but is clearly borederline second order. A) on the spectrum, label every signal with its pertinent information (intergration, multiplicity, assignment, spectroscopic notation), then identify the compound. B) determine the spectrometer frequency (use ruler and show your work) 1.(9 points total) The 'H NMR spectrum spectrum, but is clearly borderline second-order. s clearly borderline sem of a compound CiHtN is given below. It is interpretable as a first orde compound C CH2 CHs sex 2cm em 400 200

Explanation / Answer

There is no N-H proton as it would come at 3.5-4 ppm. All the protons are attached to C atoms.

The structure of the compound is CH3-CH2-CH2-CN. The protons attached to the C atoms adjacent to the CN comes at 2.4 and is a triplet due to the splitting with the adjacent CH2 protons. Splitting pattern= 2nI+1 = 2.2.1/2 + 1 =3, where n stands for no. of adjacent protons and I=1/2 for H+. A total of 2 protons have this same value as they are chemically are magnetically equivalent.

The next CH2 protons comes at 1.7, almost the value of alkane protons as the electronegative effec of N decreses through so many atoms and bonds. It splits in the following way: (2nI+1)(2nI+1)= (2.3.1/2+1)(2.2.1/2+1)= 4*3=12. But there are only six split signals as there is overlap of signals and exactly half the number appears on the spectrometer. So, 2 protons have the value 1.7, sextet.

The 3 CH3 protons have the value 1.2 and is split as: (2nI+1) = 2.2.1/2 + 1= 3 due to the adjacent CH2 protons. SO it appears as a triplet.

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