91影视

It is defined as the resonant frequency of the nucleus in relation to the standard magnetic field which is defined to be at 0 ppm (parts per million).

2.Anisotropy due to the pi-bonds that coupling the double bond and 鈥渘鈥� hydrogens splits the signal by the n+1 rule.

The molecule shows a deshielding effect because the direction of the induced magnetic field is the same as the direction of the applied magnetic field in that the net magnetic field is increased and here, the benzene shows a high chemical shift.

The molecule shows a shielding effect because the direction of the induced magnetic field is different from the direction of the applied magnetic field that the net magnetic field is decreased and here, the methane shows a low chemical shift.

Hence, as per the effect of shielding and deshielding the more reactive molecule due to de-shielding and the less reactive molecule due to shielding the order is as follow:

${\mathrm{CH}}_4<\mathrm{cyclohexane}<{\mathrm{CH}}_3{\mathrm{COCH}}_3<{\mathrm{CH}}_2{\mathrm{Cl}}_2{\mathrm{H}}_2\mathrm{C}={\mathrm{H}}_2\mathrm{C}<\mathrm{benzene}$