Abstract:

The N-Arylmethacrylamides including N-Phenylmethacrylamide(N-PhMA), N-p-Tolylmelhacrylamide (N-p-TMA), N-o-Tolylmethacrylamide(N-o-TMA),N-p-Bromomethacrylamide(N-p-BrPhMA),N-p-Nitrophenylmethacrylamide (N-p-NPhMA), N-o-Nitrophenylmethacrylamide (N-o-NPhMA), were prepared via the acid route and the chemical shifts of these N-Arylmethacrylamide were determined (see Table 1) on a Varian FT-80A NMR spectrometer.
The substituent groups affect the chemical shifts of adjacent aryl protons as shown in Table 2. Since chemical shifts depends on the electron density around the aryl proton, the methyl group, which is a weak electron releasing group on the benzene ring, increases the electron density on the aryl proton thus will tend to cause an up-field shift; the nitro group, which is a strongly electron withdrawing group on the benzene ring, decreases the electron density on the aryl proton, thus will tend to cause a down-field shift. As an evidence the shifts dH are 7.54ppm, 7.44ppm, 7.76ppm for N-PhMA, N-p-TMA, and N-p-NPhMA, respectively.

In compounds N-o-NPhMA and N-o-TMA the protons labelled dH at lower fields than those in N-p-NPhMA and N-p-TMA, since the former lies in the deshielding zone of the carbonyl group.
This is illustrated below:

The values of the chemical shifts of the six kinds of N-Aryimcthacrylamide were estimated so as to obtain a good agreement between observed and calculated.

Key words: N-Arylmethacrylamide, ¹H-NMR of unsaturatcd amide