Direct Synthesis of Amides from Carboxylic Acids and Amines by Using Heterogeneous Catalysts: Evidence of Surface Carboxylates as Activated Electrophilic Species

Abstract

Amide synthesis: In situ IR spectroscopy and HRMS provided evidence of the activation of surface carboxylates at mild temperatures (about 323 K) for the direct synthesis of amides from carboxylic acids and amines.

Mechanochemical synthesis of TiO2/NiFe2O4 magnetic catalysts for operation under RF field

“…Second, the T1-P25-0.5 catalyst contains a mixture of anatase (37 wt.%) and rutile (27 wt.%) phases with the former being known to exhibit higher catalytic activity in direct amide formation [18]. It is well-known that the amide formation requires activation of the carboxylic acid on the titania surface through interaction of the carboxylate oxygen with surface Lewis acidic Ti 4+ species [40]. The Lewis acidity of the anatase surface increases after a treatment with a sulfuric acid solution, with a potentially a relatively limited effect on Brønsted acidity [41].…”

Direct amide synthesis over core–shell TiO2@NiFe2O4 catalysts in a continuous flow radiofrequency-heated reactor

“…To increase the reaction rate, many metal oxides demonstrated catalytic activity such as CeO2, CaO, MgO, ZnO, Y2O3, TiO2, ZrO2, Nb2O5, Al2O3, SiO2 10-13 as well as solid acids like Amberlyst-15, HBEA, niobic acid, mont-K10, nafion-SiO2 and IBA 10,14 . Among them, titania provides a unique combination of low price and high catalytic activity [15][16][17] . Hosseini-Sarvari et al 15 applied nanosized sulfated titania to direct amide synthesis in a batch reactor using a wide range of substrates and obtained the yields of 70 -98 % in 3 -12 h at 115 ºC.…”

Activity patterns of metal oxide catalysts in the synthesis of N-phenylpropionamide from propanoic acid and aniline

“…[2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] Apart from the recognized effectiveness of microwave irradiation on the condensation of carboxylic acids with amines, 4,6 and some catalytic redox routes using alternative reagents, 5,8,9,16 the most attractive option for amide bond formation is the heterogeneous catalytic condensation of amines with carboxylic acids. 18 In this context, Grosjean et al also emphasized the role of the reaction system, showing significant positive effects of heat input on the amidation kinetics because of faster rates of water removal. 15 In addition, Comerford et al recently reported that silica and SBA materials are highly active in the synthesis of N-IJphenyl)-phenylacetamide at 423 K in a continuous-flow reactor at short contact times, 17 while mechanistic issues of the condensation of formic and acetic acid with 1-pentanamine on titania have been recently addressed.…”