Abstract

Metathesis reaction was used to obtain barium, calcium and zinc soaps of hemp oil. Metal salt solutions were added to freshly prepared sodium soaps of hemp oil for this purpose. The coordination of metal ions with carboxylate groups by FTIR spectroscopy, the bilayer distance and unit cells of alkyl groups of metal soaps by X-ray diffraction were investigated in the present study. The hemp seed oil analysis by GC-MS showed mainly the presence of linoleic acid (55.89%), linolenic acid (20.16%) and oleic acid (10.82 %). However, parallel to metal soaps, metal hydroxides were formed during this reaction as shown by FTIR spectroscopy and X-ray diffraction. Asymmetric carboxylate stretching vibration was observed at 1511 cm-1 for Ba soap, 1539 and 1570 cm-1 for Ca soap and at 1543 cm-1 for Zn soap. The bilayer distance of the crystals was determined as 4.41, 4.82 and 5.09 nm for Ba, Ca and zinc soaps respectively using the intensity of the first seven orders of diffraction of the bilayer distance. Material balance, FTIR spectroscopy and X-ray diffraction showed the presence of Ca(OH)2 in Ca soap and Zn(OH)2 in zinc soap

Keywords: Cannabis sativa (hemp) seed oil, saponification, FTIR spectroscopy, X-ray diffraction