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Ionic Chain-Reaction and Complex Coordination Polymerization (Addition Polymerization)
Published in Charles E. Carraher, Carraher's Polymer Chemistry, 2017
While the major metal site is zirconium, other metals have been successfully used, including Ti, Hf, Sc, Th, and rare earths (such as Nd, Yb, Y, Lu, and Sm). Cyclopentadienyls (Cps) have been the most commonly used ligands, though a number of others have been successfully employed, including substituted Cps and bridged Cps. The most widely used metal–ligand grouping is zirconocene dichloride. Zirconocene dichloride has a distorted tetrahedral geometry about Zr (5.53).
Biomass of ryegrass from field experiments: toward a cost-effective and efficient biosourced catalyst for the synthesis of Moclobemide
Published in Green Chemistry Letters and Reviews, 2021
Marie Hechelski, Christophe Waterlot, Pierrick Dufrénoy, Brice Louvel, Adam Daïch, Alina Ghinet
Five main synthetic strategies have been applied to synthesize this molecule. The most studied was the reaction between 4-chlorobenzoic acid and 2-morpholin-4-ylethanamine in the presence of various catalysts as tetramethyl orthosilicate (TMOS) (19), diphenylphosphoryl azide (DPPA)/Et3N (20), bis(pentamethylcyclopentadienyl) zirconium perfluorooctanesulfonate (21) or zirconocene dichloride (ZrCp2Cl2) (22) in different solvents such as toluene, dichloromethane or tetrahydrofurane to provide target molecule in 85–100% yield. The second synthetic pathway used 4-chlorobenzoic acid chloride and 2-morpholin-4-ylethanamine in the presence of triethylamine (3 eq.) in dichloromethane (23), disodium carbonate or sodium hydroxide (24) to provide Moclobemide in 35–95% yield. The third strategy was a transamidation of 4-chlorobenzoic amide in presence of 2-morpholin-4-ylethanamine catalyzed by mesoporous niobium oxide spheres (Nb2O5) at 160°C under argon atmosphere and allowed the synthesis of Moclobemide in 90% yield (25). The fourth method was based on the reaction between p-chlorobenzonitrile (1 eq.) and 2-morpholin-4-ylethanamine (8 eq.) with 10% mol of iron nitrate nonahydrate (Fe(NO3)3.9H2O) as catalyst under heating (125°C) for 24 h. The conversion was 71% and Moclobemide was isolated in 54% yield (26). Finally, a recent procedure reported the synthesis of the title compound in 90% yield using methyl 4-chlorobenzoate (1 eq.) and 2-morpholin-4-ylethanamine (2 eq.) and necessitating an excess of strong base LiHMDS (3 eq.) in THF (10). In the current study, Moclobemide was obtained from an equimolar mixture of methyl 4-chlorobenzoate 1 and 2-morpholin-4-ylethanamine 2 in the presence of the biosourced catalyst (Scheme 1). The reaction was conducted under two temperature conditions (40°C and 100°C) and blank was made to evaluate the effect of our biosourced catalyst on the reaction rate and yield. For the four conditions, an equilibrium was reached 24 h after the beginning of the reaction. The reaction yields at 40°C were below 5% in the absence of catalyst and 40% in the presence of biocatalyst whereas they were 25% and up to 80% at 100°C, respectively. The melting point of Moclobemide was 141°C and the retention factor (Rf) was 0.31. The characteristic infrared bands were 3276, 2969, 2943, 2812, 1634, 1541, 1486, 1310, 1116 cm−1 (Figure 1) and the nuclear magnetic resonance (NMR) of the nuclei 1H and 13C (Figures 2A and B) were described hereafter.