By subtracting the resonant frequencies of pairs of adjacent lines in the proton

Question

By subtracting the resonant frequencies of pairs of adjacent lines in the proton NMR quartets, calculate they values in Hz. Also calculate the chemical shift (ppm value) of each quartet by taking the average of the two central lines. Frequencies in Hz can be converted to ppm by dividing by the NMR frequency in MHz. Where resonant frequencies are given in units of ppm, convert from ppm to Hz by multiplying by the NMR frequency in MHz. J couplings should be reported to one value after the decimal point and ppm values to three values (e.g.: 6.6 Hz; 3.251 ppm).

Explanation / Answer

Calculating coupling constants-Rules-

For a quartet ,coupling constant J=difference of resonant frequency of adjacent lines(Hz)[All the gaps are of equal frequency in each quartet.peak intensity is1:3:3:1]

chemical shift=average frequency of two central lines(Hz)

frequency in ppm=frequency in Hz/NMR frequency in MHz

1)J=354.61Hz-348.80Hz=5.81Hz

2) chemical shift=348.80Hz+343.01Hz/2=345.9Hz

chemical shift (in ppm)=345.905Hz/300 MHz=1.153 ppm

Related Questions

Navigate

• Browse (All)
• Browse B
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.