Solvent dependent N-14 chemical shifts in quinoline

N-14 chemical shifts of neat quinoline and 90% quinoline in different solvents have been measured. DMSO-d(6) was used as an internal locking agent NH4NO3 wits used as an external standard. The N-14 chemical shift of neat quinoline with respect to NO3. ion is -71.75 ppm previously reported N-14 chemical shifts by this group in pure quinoline was -72 +/- 2 ppm in external lock mode. The internal lock result are more accurate. The chemical shifts of 90% quinoline in carbon tetrachloride, chloroform and dioxane are nearly the same i.e -71.57, -73.61 and -70.14 ppm respectively. The N-14- chemical shifts of 90% quinoline in water and methanol are relatively low i.e. -135.87 and -109.96 ppm respectively. This is due to hydrogen-bonding of nitrogen with water and methanol. In DMSO and acetone the N-14 chemical shifts are - 63.41 and -62.78 ppm respectively. This may be due to complex formation of these compounds with quinoline. In all such cases N-14 studies has been done at a frequency of 6.43 MHz using JEOL FX 90Q FT NMR. To avoid the base line rolling due to low frequency and acoustic ringing a delay time of 400 mus has been used.

A W K KHANZADA ,SHAMA PATHAN ,