Solventless Amide Synthesis Catalyzed by Biogenic CaCO₃ Materials

Abstract

Biogenic carbonates were studied as catalysts in this work for the direct synthesis of amides under solvent-free conditions. Solids were synthesized by microbial coprecipitation of CaCl 2 and Ni salts and Cu and Fe salts. The catalysts were characterized by thermogravimetric analysis, nitrogen physisorption measurements, X-ray diffraction, and X-ray photoelectron spectroscopy. The polymorphism, hydrophilicity, and textural properties depended on the metal oxides type incorporated on CaCO 3 . N-Arylsuccinimides synthesis was employed as test reaction, obtaining remarkable selectivity and conversion in the reaction of succinic acid with p-toluidine and aniline, respectively. Optimized conditions were subsequently extended to the solvent-free synthesis of diverse amides in good yields using CuO−CaCO 3 as the catalyst in air. The direct amidation protocol was amenable to the use of different primary amines and nonactivated carboxylic acids.

Large-Scale Amide Coupling in Aqueous Media: Process for the Production of Diazabicyclooctane β-Lactamase Inhibitors

“…Water is the most economical solvent; it is abundant in nature, readily recyclable, environmentally benign, less harmful, safe to transport, nonflammable, easy to handle, and has a higher heat capacity. , The use of water as a solvent instead of toxic and hazardous solvents considerably reduces waste generation. , Using EDC.HCl/1-hydroxybenzotriazole (HOBt) has multiple advantages over other coupling agents. Limited reports are available for describing the amide coupling in aqueous media at room temperature. ,,,,,− …”

Synthesis, Characterization, and DFT Studies of N-(3,5-Bis(trifluoromethyl)benzyl)stearamide

“…The releasing of water as the unique by-product gives this approach a remarkable ecofriendly quality. Accomplishing the synthesis of the amide 3 contributed to expanding our previous amide library [27]. The MEP total density showed an electron-rich region around the carbonyl oxygen, whereas an electron-deficient region is located around the amide nitrogen.…”

“…Hence, in the past two decades, there was a significant increase in the development of sustainable catalytic methods for amide bond formation under mild conditions with a broad synthetic scope [23][24][25][26]. In particular, we recently reported a solventless direct amidation of non-activated carboxylic acids with amines employing a biogenic CuO−CaCO 3 catalyst for amide synthesis in moderate to high yields under normal atmospheric conditions [27]. Despite the elegant progress that has been accomplished, most catalytic direct amidation methods are unattractive for large-scale production owing to the limited substrate scope, low energy efficiency, poor sustainability, and not industrially relevant levels of recyclability of most current catalysts [23,24].…”

“…Importantly, the metal-and catalyst-free direct amidation of carboxylic acids with amines has been neglected for many years owing to its high temperatures and long reaction times; nonetheless, this thermal approach can eliminate some of the previously reported synthetic drawbacks. In connection with the ongoing development of efficient and simple protocols for the construction of carbon-nitrogen bonds [27][28][29][30][31] and our current studies on the synthetic utility of benzylamine derivatives [32,33], we describe a solventless synthesis of N-(3,5bis(trifluoromethyl)benzyl)stearamide 3 through an uncatalyzed process under normal atmospheric conditions. Moreover, molecular electrostatic potential studies, determination of quantum descriptors, fundamental vibrational frequencies, and intensity of vibrational bands were computed by the B3LYP method using 6-311+G(d,p) basis set in gas phase.…”

Ring Opening/Site Selective Cleavage in N-Acyl Glutarimide to Synthesize Primary Amides

“…For instance, primary amides observed in many drugs show biological activity, such as Gilteritinib, an anticancer drug, ribavirin, which is used to treat hepatitis C, and safinamide, , which is for treating Parkinson’s disease. Generally, primary amide preparation can be carried out via the conventional method by the reaction of ammonia with carboxylic acids − and carbonyl derivatives , or through the hydration of nitriles , (Figure a). Because of the importance of amides, various new nonclassical strategies were developed.…”