Mechnochemical Synthesis And Characterization Of Cerium (Lanthanum) Ferulate

Ferulic acid (4-hydroxy-3-methoxycinnamic acid) has received much attention in the study of Chinese medicine since it was found to be one of the effective components in Chinese medicine herbs such as Angelica sinensis and Cimicifuga heracleifolia. In recent years, there have been an increasing number of reports on the physiological functions of ferulic acid and its derivatives in human. Many applications of ferulic acid in the food industry have also been discovered. In this paper, we have synthesized some complexes of ferulic acid with rare earth elements by simple mechanochemical method, which may provide the investigation of pharmaceutical functions of ferulic acid and rare earth elements with basic materials.Cerium ferulate (CF) complex was synthesized via mechnochemical reaction using cerium nitrate (CN) and ferulic acid (FA) as starting materials. The effects of feeding molar ratio as well as the addition of proton acceptor hexamethylene tetramine (HMTA) and dispersant polyethylene glycol (2000, PEG) on the conversion percentage of cerium were investigated. The as-synthesized complex was characterized by means of IR and ¹H NMR spectra. The results showed that the direct cation exchange reaction between cerium nitrate and ferulic acid did not occur due to the weak acidity of ferulic acid. Therefore, the addition of HMTA had taken an important role in the formation of cerium ferulate complex. With the increase of addition amount of HMTA, the conversion percentage of cerium increased. However, in order to force cerium completely convert to complex, the molar rations of FA to CN and HMTA to FA should be reached up to 6:1 and 1.5:1 respectively. The addition of PEG also improved the conversion of cerium to its ferulate complex, and the suitable addition amount was found to be 1-2%. With above conditions, the milling time for a conversion percentage of cerium over 99.5% was only 30mins. The composition of the as-synthesized complex was determined by elementary analysis to be (C₁₀H₉O₄)₃Ce·3H₂O. And the coordination was confirmed by IR and ¹H NMR to occur between cerium ion and the oxygen atom of carboxyl in ferulate groupThe TG-DTA results showed that CF underwent two strong exothermal processes at 275℃and 325℃after losing water, and completely decomposed into ceria over 350℃. Therefore, ceria powders with size ranging from 50 to 100 run were obtained by calcining CF which was prepared with the addition of PEG.Lanthanum ferulate (LF) was also prepared by the similar method as CF. XRD patterns and IR spectra of the final product showed the formation of LF. The specific surface area of the as-synthesized CF was higher than that of CF, indicating the particles formed during milling were fine dispersed.At the same time, phenanthroline (Phen) or 8-hydroxyquinolin (8HQ) was used as a second ligand for coordinating to lanthanum ion with ferulate group. By milling the mixture of lanthanum nitrate (LN), FA, HMTA, PEG 2000 with Phen or with 8HQ for 1 h, and washing with water and alcohol, two ternary complexes with compositions of La(FA)₂₅(Phen)_0.9 3H₂O and La(FA)₂(8HQ)₂2H₂O were prepared.