A surface active agent is a substance added to a liquid that is useful for increasing the spreading properties by weakening the surface tension of the liquid. The need for biosurfactants continues to ...increase along with industrial developments and increasing human awareness of good health and the environment. In this study, the surfactant alkyl diethanolamide (Alkyl-DEA) was synthesized using one type of amine alcohol, namely diethanolamine, through an amidation reaction between palmitic acid and using hexane-isopropanol solvent and calcium oxide catalyst. Surface properties in the form of acid number, saponification number, and HLB value were studied by observing the effect of the reaction variables on the three surface properties. This study showed that the best conversion of palmitic acid was obtained at 70oC and 80oC for a reaction time of 5 hours and a stirring speed of 150, 200, and 250 rpm. The relationship between reaction rate and time is directly proportional; the longer the reaction time, the reaction rate will increase. However, increasing the reaction time did not give significant results to the surfactant product. The relationship between reaction temperature and conversion gain decreased with increasing reaction temperature. The acid number obtained under the best conditions was 39.27, the saponification number was 30.85, and the HLB value was 4.29.
The front cover picture, depicts Metalaxyl, an acylalanine fungicide, which was synthesized through catalytic continuous sequential‐flow reactions. A halide‐free approach including two ...continuous‐flow catalytic processes, heterogeneous Pt‐catalyzed reductive alkylation and homogeneous acid‐catalyzed amidation with an acid anhydride, was developed to minimize waste and enhance efficiency. Systematic examination of the two reactions in flow mode enabled a high‐yielding, two‐step sequential continuous‐flow process, achieving continuous synthesis of an agrochemical. Details can be found in the Communication by Shu Kobayashi and co‐workers (H. Ishitani, Z. Yu, T. Ichitsuka, N. Koumura, S.‐y. Onozawa, K. Sato, S. Kobayashi, Adv. Synth. Catal. 2022, 364, 18–23; DOI: 10.1002/adsc.202100898).
Here we report a cytochrome P450 variant that catalyzes C2-amidation of 1-methylindoles with tosyl azide via nitrene transfer. Before evolutionary optimization, the enzyme exhibited two undesired ...side reactivities resulting in reduction of the putative iron-nitrenoid intermediate or cycloaddition between the two substrates to form triazole products. We speculated that triazole formation was a promiscuous cycloaddition activity of the P450 heme domain, while sulfonamide formation likely arose from surplus electron transfer from the reductase domain. Directed evolution involving mutagenesis of both the heme and reductase domains delivered an enzyme providing the desired indole amidation products with up to 8400 turnovers, 90% yield, and a shift in chemoselectivity from 2:19:1 to 110:12:1 in favor of nitrene transfer over reduction or triazole formation. This work expands the substrate scope of hemoprotein nitrene transferases to heterocycles and highlights the adaptability of the P450 scaffold to solve challenging chemoselectivity problems in non-natural enzymatic catalysis.
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•Fine pyrite (−26 μm) flotation was improved by combined use of two reagents.•Particle size of fine pyrite was flocculated to a value suitable for flotation.•Amidation of two reagents ...caused hydrophobic and flocculation of fine pyrite.•Reticulated polymeric hydrophobic product may generate on the surface.
Hydrophobic flocculation is one of the effective method to solve the fine flotation. In this paper the hydrophobization and flotation performance of coco-alcyl-amine-acetate (C-1) on fine pyrite (−26 μm) was improved by ethylenediamine-N, N'-bis (2-hydroxyphenyl) acetic acid (C-2) and the corresponding interaction mechanism was discussed. Turbidity and microscope measurements show that fine pyrite can be better flocculated to an easily floated size using mixed C-1/C-2 (1:1) reagent scheme pH 8.5. Surface micropolarity results display that the flocculation of fine pyrite using mixed C-1/C-2 is mainly through the hydrophobization of it by reagent adsorption. C-2 and C-1 promoting the adsorption of each other could be implied by the significantly change in the surface roughness of pyrite. FTIR results show the amidation between the –NH– in pre-adsorbed C-1 with the –COO– of C-2. Hydrophobic and bridging flocculation are the primary and secondary factors of the bigger floc size. Considering the possibility of the amidation between –NH– in C-2 and -COS- in C-1 and thus the formation of reticulated polymer, the importance of the bridging flocculation may go up, which needs further study. The better flotation recovery of fine pyrite with mixed C-1/C-2 is consistent with the detection results and deductions.
The construction of C(sp3)–N bonds via direct radical–radical cross-coupling under benign conditions is a desirable but challenging approach. Herein, the cross-coupling of alkyl and amidyl radicals ...to build aliphatic C–N bonds in a concise, mild, and oxidant-free manner is implemented by nickel/photoredox dual catalysis. In this protocol, the single electron transfer strategy is successfully employed to generate N- and C-centered radicals from sulfonyl azides/azidoformates and alkyltrifluoroborates, respectively. The photocatalyst-induced triplet–triplet energy-transfer mechanism, however, might not be applicable to this reaction. The oxidative quenching pathway of the excited photocatalyst (RuII/*RuII/RuIII/RuII) combined with a possible NiI/NiII/NiIII/NiI catalytic cycle is proposed to account for the nickel/photoredox dual-catalyzed C(sp3)–N bond formation based on synergistic experimental and computational studies.
A nickel-catalyzed reductive amidation of unactivated esters was recently reported, employing readily available and low-cost nitroarenes as nitrogen sources. Here, we describe a comprehensive ...experimental and computational study, which reveals an intricate mechanism of this process. The reaction profile indicated azoarene as the terminal nitrogen intermediate formed from the reduction of nitroarene. The activation of azoarene en route to amidation was probed by kinetics, Hammett plots, and density functional theory (DFT) calculations. The activation likely involves Ni-catalyzed, ZnCl2-promoted, reductive cleavage of the NN double bond in an azoarene to form a bridging imido species, which then reacts in a rate-determining step with an ester to give an amide. Besides the nickel catalyst, ZnCl2 has an important influence on the rates and orders of the reaction. DFT computations suggest ZnCl2 stabilizes many of the intermediates in the reaction pathway of azoarene activation, including forming the key Ni–Zn heterobimetallic imido intermediate. The mechanistic insights revealed in this study lay the foundation for the development of synthetic methods employing azoarenes as stable and easily accessible nitrogen sources.
•Amidation of diphenolic acid can avoid by-reactions in the epoxidation.•Amidation was found to be able to lower toxicity of diphenolic acid.•Diphenolic amides exhibited an autocatalytic effect on ...epoxy polymerization.•The amidation strategy realize superior material properties than DGEBA resin.•Enhanced compatibility with cotton fibers for preparing was observed.
Bisphenol A (BPA) is the main precursor in the synthesis of epoxy resins. However, because of its toxic and nonrenewable nature, BPA is unsuitable in the sustainable preparation of epoxy resins. In contrast, Diphenolic acid (DPA) is renewable but its carboxyl group limits its applications in bio-based thermosets. In this study, we report a novel amidation route to tailor DPA to produce epoxide monomers that present epoxy resins with a high performance. The diphenolic amides exhibited very low toxicities when compared with that of BPA, and also provided an unexpected autocatalytic effect on the curing reactions when succinic anhydride (SA) was used as the hardener. Dynamic mechanical analyses (DMA) and tensile test results confirmed the remarkable thermomechanical properties of the cured epoxy resins, which may be attributed to the increased cross-linking density and enhanced hydrogen bonding by the amide groups. Among the SA-cured epoxy resins, diglycidyl ether of diphenolic ethylamide exhibited the best performance, which included a high Tg of 114 °C, char yield (CY) of 20%, tensile strength of 60.2 MPa, and toughness value of 185 MPa. In addition, the DPA-derived epoxy resins have great potential in the preparation of bio-based composites because they act as excellent interfaces between the resin and cotton fibers (CoFs). Our study presents a new strategy to prepare bio-based epoxy resins with a high performance, emphasizing the greater potential of amidated DPA derivatives to replace BPA in the epoxy resin market.
The Ir‐catalyzed mild CH amidation of benzoic acids with sulfonyl azides was developed to give reactions with high efficiency and functional‐group compatibility. Subsequent protodecarboxylation of ...ortho‐amidated benzoic acid products afforded meta‐ or para‐substituted (N‐sulfonyl)aniline derivatives, the latter being inaccessible by other CH functionalization approaches. The decarboxylation step was compatible with the amidation conditions, enabling a convenient one‐pot, two‐step process.
Without a trace: Carboxylic acids are used as traceless directing groups in the Ir‐catalyzed direct CH amidation of arenes with sulfonyl azides under mild conditions. The tandem protodecarboxylation of the ortho‐amidated benzoic acid products afforded meta‐ or para‐substituted (N‐sulfonyl)anilines, which are difficult to obtain by other CH functionalization approaches.
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In this study, we report on the ability of DMTMM PF6 to improve the amidation reaction. The on-DNA amidation reaction using DMTMM PF6 demonstrates higher conversion rates than those ...using HATU or DMTMM Cl, particularly with challenging sterically hindered amines and carboxylic acids. The developed method enables the expansion of available building blocks and the efficient synthesis of high-purity DNA-encoded libraries.
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•Simple and efficient strategy for the oxidative cross-coupling CN bond formation.•Using a nontoxic and easily available ligand free iron catalyst and an atom-efficient oxidant ...(O2).•The reaction has broad substrate scope.
An efficient iron-catalyzed dehydrogenative cross-coupling amidation/imidation reaction between N,N-dimethylanilines and amides/imides is reported. The protocol uses an inexpensive and readily available Fe(NO3)3·9H2O/O2 catalytic system in the absence of additional ligands at room temperature.
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