Enrichment of nervonic acid in Acer truncatum Bunge oil by combination of two-stage molecular distillation,one-stage urea complexation and five-stage solvent crystallization

Nervonic acid is the world’s first and only potent substance that can repair damaged nerve fibers and promote nerve cell regeneration with high nutritional value.The wide variety of fatty acids in plant oils and fats with similar structures makes the large-scale separation and purification of high-purity nervonic acid very difficult.A new combined process of molecular distillation,urea inclusion and solvent crystallization was established to prepare high-purity nervonic acid with the mixed fatty acids obtained after saponification and acidification of Acer truncatum Bunge oil as raw materials.First,according to the difference in the mean free path of fatty acids,molecular distillation was used to separate and remove C16 saturated fatty acid of palmitic acid and four C18-C20 fatty acids of stearic,oleic,linoleic,and linolenic acids.The content of C16-C20 fatty acids decreased from 72.92% to 19.22% after two-stage molecular distillation processes,in which the contents of saturated fatty acid of palmitic acid decreased to about 0.5%.Then,according to the difference in carbon chain length and saturation of fatty acid,the contents of C22-C24 saturated fatty acids of tetracosanoic and docosanoic acids decreased to 0.21% and 0.07% by urea inclusion with urea/free fatty acid preparation by saponification(SPOMFs)ratio as 0.6.In addition,all saturated fatty acids were basically separated.Finally,according to the difference in the solubility of fatty acids in solvents,the C18-C20 unsaturated fatty acids of oleic,linoleic,and linolenic acids and C22 unsaturated fatty acid of erucic acid were removed by solvent crystallization.The content of C18-C20 unsaturated fatty acids decreased to less than 5% with pentanol as the solvent after the first stage solvent crystallization.The content of erucic acid decreased to 3.47% with anhydrous ethanol as the solvent after the second to fifth stage solvent crystallization.The combined process of molecular distillation,urea inclusion and low temperature crystallization innovatively adopted an efficient,simple and easy-toindustrial solvent crystallization method to separate erucic and nervonic acids,obtaining nervonic acid with purity of 96.53% and final yield of 47.99%.

Structural and AC electrical properties study of solid metal urea complexes

The complexation of solid urea with(Co^(2+)),(Cu^(2+))or(Ni^(2+))ions has been studied by using dielectric spectroscopy technique over a wide frequency range at different temper atures.Samples'structure were investigated by XRD,FTIR and FT-Raman spectroscopy.FIIR and Raman analy sis indicated that the urea coordinates with the metal atoms through the same oxygen-metal bond(O-M).Furthermore,XRD analysis showed that the samples have polycrystalline structure with single phase.The pemittivity of complexes was found at much higher values than that of the ligand(pure urea),showing structure dependency.Furthermore,two relaxation peaks were observed in the dielectric loss spectra corresponding to the orientation po larization of urea molecule,and some parts of urea molecule may be NH2 groups.Both relaxation peaks correspond to thermally activated because they were shifted to higher frequency with the temperature increase.The peak position for the low frequency relaxation peak was observed lht the same relaxation time(τ=7.6× 10^(-4) s),corresponding to the coordination mode through the same O-M bond.Novelty of this work is the successful finding of the relationship between the crystalline phase,coordination mode and the dy namic molecular behavior of solid urea and its complexes using the dielectric spec-troscopy techn ique.

Isomorphism in ternary complex:Poly(ethylene oxide),urea and thiourea

Herein,we demonstrated that poly（ethylene oxide）（PEO）,urea and thiourea can crystallize into novel ternary complex with the molar ratio of guest polymer and host small molecule as 3：2,and proved that the ternary complex behaves isomorphism phenomenon by varying the ratio between urea and thiourea for the first time.This observation gives a boost to prepare co-crystals of different small molecules that cannot be obtained by direct mixing without the aid of polymer chains.