Double Addition Research Articles

Gold‐Catalyzed Annulation Between 1‐[2‐(Dimethoxymethyl)phenyl]prop‐2‐yn‐1‐yl Acetates and α‐Diazo Esters or Anilines to Form Substituted Naphthoates and Indeno[1,2‐b]quinoline, Respectively

AbstractThis work describes gold‐catalyzed annulations of 1‐(2‐(dimethoxymethyl)phenyl)‐1‐prop‐2‐yn‐1‐yl acetate substrates with α‐diazo esters and anilines, respectively yielding substituted naphthoates and indeno[1,2‐b]quinoline derivatives. Our mechanistic analysis indicates 1‐methoxy‐2‐carbonyl‐1H‐indenes as their common intermediates. In the formation of naphthoates, α‐diazo ester attacks at gold‐bound intermediate via an SN2 pathway to enable a allylic methoxy substitution. For indeno[1,2‐b]quinoline derivatives, there are two main reactions, including (i) a reversible formation between intermediate and a double amine addition product and (ii) an arylation reaction of intermediate. Species N‐(phenyl((2E)‐1‐(phenylimino)‐1,3‐dihydro‐2H‐inden‐2‐ylidene)methyl)aniline was converted to indeno[1,2‐b]quinoline in the presence of gold catalyst.

Mechanistic Insights into the cis-Selective Catalytic Ring-Opening Metathesis Polymerization.

Cis-selective ring-opening metathesis polymerization (ROMP) with the commercial Grubbs "nitrato catalyst" has shown promise for synthesizing stereoregular materials, but it comes with the drawback of losing control over the molecular weight due to the poor initiation rate of the catalyst and the need for stoichiometric ruthenium complex loading. To address these issues, we developed a chain transfer polymerization method that allows for the catalytic synthesis of polymers while controlling the degree of polymerization. This allowed us to produce shorter polymers with exceptional chain-end control. Analysis of the polymers revealed a novel double monomer addition mechanism for this catalyst. MALDI-ToF mass spectrometric measurements showed that when using small monomers like norbornene, the polymer chains contained only odd numbers of monomers. In contrast, the polymerization of norbornene-imide-type monomers shows a major distribution with odd numbers of monomers along with a minor distribution of even numbers. This unique distribution of polymer chain types had not been previously observed in ROMP. We explain this phenomenon by the chiral nature of the catalyst that yields two isomeric catalytic species with dissimilar reactivities toward monomer and chain transfer agents.

Preparation and properties of polyamide elastomers by a new synthesis route of Michael addition reaction

At present, the mainstream industrial synthesis method of polyamide is still bulk fusion polymerization, which is not in line with the concept of green synthesis because of the high threshold of reaction conditions and large energy consumption. Based on this, a new synthesis route of polyamide elastomer was studied in this paper. By synthesizing the end-functionalized long carbon chain diacrylamide (DDA) containing amide bonds, the synthesis mechanism was made by the thiol double bond Michael addition reaction. A series of polyamide elastomers with different ratios of hard and soft segments were synthesized by using dimercaptan chain extenders with different molecular weights. The results showed that the new synthesis route successfully prepared DDA and polyamide elastomers. The mechanical properties of the products were excellent, and the strain rate could reach 383 %. Tensile strength up to 23.08 MPa. The synthesis route has the characteristics of simple reaction process, mild reaction conditions and high reaction conversion rate. It provides theoretical guidance for the new synthesis route of polyamide elastomer.

Tetrasubstituted Chromanone Synthesis by a Tandem Oxa‐Michael/Michael Addition Reaction of 2‐Hydroxyacetophenones and Alkynyl Nitriles

An efficient transition metal‐free approach for the synthesis of chroman‐4‐ones via double conjugate additions of 2‐hydroxyacetophenones on alkynyl nitriles utilizing NaH as a base has been realized. This operationally simple protocol offers library of 4‐chromanones in moderate to good yields.

Vortex-Assisted Magnetic Solid-Phase Extraction of Heavy Metals in Water and Food Samples Using Iron Oxide Nanoparticle-Impregnated Carboxymethyl-β-Cyclodextrin.

The excessive accumulation of heavy metals has adverse effects on the human body. Here, magnetic iron oxide-impregnated carboxymethyl-β-cyclodextrin was synthesized. The synthesized material was employed as a magnetic solid-phase extracting adsorbent for specific heavy metals like lead (Pb), nickel (Ni), copper (Cu), and cobalt (Co). Characterization was performed by X-ray diffraction, energy dispersive X-ray spectroscopy, scanning electron microscopy, Brunauer-Emmett-Teller, and Fourier-transform infrared spectroscopy. The analytical merits, like detection limits (Pb: 1.38ng/mL, Ni: 0.5ng/mL, Co: 0.14ng/mL, and Cu: 0.55ng/mL) andquantification limits (Pb: 4.14ng/mL, Ni: 1.62ng/mL, Co: 1.85ng/mL, and Cu: 1.82ng/mL) were calculated. Similarly, the preconcentration and enhancement factors (15) and relative standard deviation (Pb: 3.5, Ni: 0.92, Co: 2.7, and Cu: 1.5) were also calculated. The interfering study shows that the method is highly selective. For validation, it was applied to certified reference materials such as the Institute of Nuclear Chemistry and Technology ornamental Basma tobacco leaves and trace metal double addition 63.4 environmental water with good percent recovery values (92%-99%). Real water and food samples were also used with satisfactory (90%-99%) recovery results.

Metal-free double azide addition to strained alkynes of an octadehydrodibenzo[12]annulene derivative with electron-withdrawing substituents.

Strain-promoted azide-alkyne cycloaddition (SpAAC) is a powerful tool in the field of bioconjugation and materials research. We previously reported a regioselective double addition of organic azides to octadehydrodibenzo[12]annulene derivatives with electron-rich alkyloxy substituents. In order to increase the reaction rate, electron-withdrawing substituents were introduced into octadehydrodibenzo[12]annulene. In this report, the synthesis of new octadehydrodibenzo[12]annulene derivatives, regioselective double addition of organic azides, and an application to crosslinking polymers are described.

Efficient and facile dual post-polymerization modification using acetoacetate-acrylate Michael addition

Post-polymerization modification (PPM) is a valuable strategy for achieving diversified functional polymers; nonetheless, the pursuit of achieving mild and efficient dual modification along the polymeric backbone remains as a challenge. In this work, the Michael addition reaction of acetoacetates and acrylates have been demonstrated as a robust PPM technique. The reversible addition-fragmentation chain transfer polymerization of commercially available 2-(acetoacetoxy)ethyl methacrylate provides a polymer scaffold with controlled molecular weight and acetoacetate groups. These pendant groups are capable of undergoing efficient double addition reactions with acrylates, leading to an increased density of functional moieties within the polymeric backbone. This PPM reaction exhibits unique advantages such as mild reaction conditions (at 40 °C), rapid kinetics (completion within 1 h), and high atom economy. Consequently, a series of polymers with tunable thermal stability, glass transition temperature, and hydrophilicity have been successfully synthesized. Applications have been demonstrated for both the synthesis of polymers exhibiting aggregation-induced luminescence and the preparation of luminescent materials with adjustable mechanical properties. This pioneering work unveils a robust post-polymerization modification technique, significantly advancing the synthesis of innovative functional polymers.

Zn–Al with NO2− as a corrosion inhibitor epoxy-coated carbon steel under artificial atmospheric conditions

This study evaluated Zn–Al–NO2− layered double hydroxide as a corrosion inhibitor in a high-thickness epoxy resin coating (200 µm). The layered double hydroxide was tested in a NaCl solution, using electrochemical impedance spectroscopy. The formed oxides were analysed by X-ray diffraction and energy dispersive X-ray spectroscopy. The corrosion resistance of the epoxy coating (with and without layered double hydroxide) was analysed by electrochemical impedance spectroscopy after exposure to a NaCl solution, salt spray, or a weather-O-meter chamber in a simulated atmospheric environment. The electrochemical impedance spectroscopy measurements for the free layered double hydroxide in a NaCl solution revealed that layered double hydroxide prompted the formation of a compact, protective, and insoluble oxide layer on the carbon steel surface. The Cl− permeability through the epoxy resin film was 5.88 times lower for the film containing layered double hydroxide than for the control. The layered double hydroxide was added to the epoxy coating at a 5 wt-% to evaluate the behaviour of the coating in aggressive environments. The entry of aggressive ions was controlled by the ability of the layered double hydroxide to capture them and release the corrosion inhibitors. Thus, the layered double hydroxide worked as a trap for these aggressive ions and enhanced the performance of the coating. Therefore, a layered double hydroxide addition could benefit a high-thickness coating exposed to an aggressive environment and UV radiation.

Improved Arithmetic on Koblitz Curves over Binary Field

The longest process in ECC is the elliptic curve scalar multiplication. The structure of this operation involves three mathematical levels; this work aims to study issues that arise in the efficient implementation of this operation, specifically targeting the point arithmetic level for the Koblitz curve over a binary field. Theorems have been made for a speedy point doubling and point addition operation, in these theorems Jacobian coordinate modification has been considered, where these coordinates represent each point: refers to a point on a curve over . This occurs when a coordinate system represents any point on a Koblitz curve over a binary field. By choosing the right coordinate system, it is possible to speed up the elliptic curve scalar multiplication using this method.

Organocatalytic Desymmetric Double Aza-Michael Addition Cascade: Enantioselective Synthesis of Fused Morpholines.

Double aza-Michael addition (DAM) has become an emerging strategy for the construction of two carbon-nitrogen bonds in a single step, which can significantly simplify the synthesis of N-heterocycles. Hitherto, their asymmetric catalytic genre remains unattempted. Herein, we describe the judicious design of an organocatalytic enantioselective desymmetric double aza-Michael addition cascade to access a series of functionalized fused morpholines with excellent yields and diastereo- and enantioselectivities. A one-pot telescopic synthesis was demonstrated for a bridged triheterocyclic compound. In addition, scale-up synthesis and various attractive postsynthetic modifications of the title products amplify the significance of the current methodology.

Methylmercury cycling in the Bohai Sea and Yellow Sea: Reasons for the low system efficiency of methylmercury production

Coastal seas contribute the majority of human methylmercury (MeHg) exposure via marine fisheries. The terrestrial area surrounding the Bohai Sea and Yellow Sea (BS and YS) is one of the mercury (Hg) emission “hot spots” in the world, resulting in high concentrations of Hg in BS and YS seawater in comparison to other marine systems. However, comparable or even lower Hg levels were detected in seafood from the BS and YS than other coastal regions around the word, suggesting a low system bioaccumulation of Hg. Reasoning a low system efficiency of MeHg production (represented by MeHg/THg (total Hg) in seawater) may be present in these two systems, seven cruises were conducted in the BS and YS to test this hypothesis. MeHg/THg ratios in BS and YS seawater were found to be lower than that in most coastal systems, indicating that the system efficiency of MeHg production is relatively lower in the BS and YS. The low system efficiency of MeHg production reduces the risk of Hg in the BS and YS with high Hg discharge intensity. By measuring in situ production and degradation of MeHg using double stable isotope addition method, and MeHg discharge flux from various sources and its exchange at various interfaces, the budgets of MeHg in the BS and YS were estimated. The results indicate that in situ methylation and demethylation are the major source and sink of MeHg in the BS and YS. By comparing the potential controlling processes and environmental parameters for MeHg/THg in the BS and YS with the other coastal seas, estuaries and bays, lower transport efficiency of inorganic Hg from water column to the sediment, slower methylation of Hg, and rapid demethylation of MeHg were identified to be major reasons for the low system efficiency of MeHg production in the BS and YS. This study highlights the necessity of monitoring the system efficiency of MeHg production, associated processes, and controlling parameters to evaluate the efficiency of reducing Hg emissions in China as well as the other countries.

High-efficiency anaerobic digestion of soybean curb residue with simultaneous phosphorus recovery by Mg[sbnd]Fe layered double hydroxides addition

Anaerobic digestion of food waste faces several technical problems, such as process failure caused by over-acidification, low heating value of biogas, and high treatment cost of liquid digestate. Layered double hydroxides (LDH) are expected to simultaneously enhance biogas production and quality and immobilize soluble phosphorus in AD due to their excellent anion exchange capability. This study first verified the above hypothesis, indicated by a dramatically enhanced methane yield of 17 folds under a high substrate load and a high quality of generated biogas with 89 % methane content and 90 % lowered hydrogen sulfide. Meanwhile, the soluble phosphorus was efficiently reduced to 3 mg/L after AD. Moreover, the calcined product of LDH showed comparable performance, indicating the possibility of reusing LDH in the AD process. The above results implied the great potential of LDH as a multifunctional material for enhancing the efficiency of waste treatment and energy/resource conversion in the AD process.

Double additive electrolyte solvation engineering to achieve long cycle and high capacity sodium-ion battery

Sodium-ion batteries are a promising energy storage system due to their rich sodium resources and many other advantages. However, its development is severely hampered by the electrolyte's low compatibility with the electrode contact. Herein, we propose a solvation control strategy with ethoxy (pentafluoro) cyclotriphosphazene (PFPN) and NaClO4 double additives to reconstruct the solvation structure of sodium ions in electrolytes. This enables the electrolyte to form a dense and stable solid electrolyte interlayer (SEI) and double-layer cathode electrolyte interphase (CEI) on the surface of the electrode material to achieve long-cycle and high-capacity sodium-ion batteries. PFPN can form a stable SEI rich in inorganic components at the anode interface. ClO4- can first reach the cathode surface to create a NaCl and polymer-like chain CEI with sodium ions and solvents, and then the PFPN derivatives are migrated to the cathode surface to open the ring and decompose, thus forming a double-layer stable CEI. Therefore, the PEDN electrolyte can simultaneously improve the interface stability of the battery's cathode and anode solid electrolyte. Hence, the capacity retention rate of the 4.5 Ah Na3Fe2(PO4)P2O7 (NFP)||hard carbon (HC) pouch cell after 2500 cycles at 1C is 88.26%.

Preparation of Hetero‐π‐Conjugated Compounds by Double Nucleophilic Addition to Haloalkynes and C−H Cyclization

AbstractWhen a mixture containing 1‐halo‐1‐alkyne, a dinucleophilic agent, and a base (Cs2CO3 or K3PO4) was heated in DMF, regio‐ and stereo‐selective nucleophilic addition of the dinucleophilic agent to the acetylenes occurred. This reaction yielded (Z,Z)‐bis(haloalkene), which subsequently underwent Pd‐catalyzed cyclization through C−H bond activation, resulting in the formation of two‐oxygen‐ or ‐nitrogen‐containing hetero‐π‐conjugated compounds. N‐(5‐Hydroxynaphthalen‐1‐yl)methanesulfonamide was treated with 2‐phenyl‐1‐chloroethyne followed by 1‐chloro‐1‐hexadecyne. After these reactions, Pd‐catalyzed double C−H cyclization was employed to produce 1H‐2‐phenyl‐7‐tetradecylbenzofuro[7,6‐g]indole. Notably, this compound transformed into a fan‐shaped structure at 86 °C and transitioned into a smectic A phase characterized by a layered structure.

Unexpected high yield of acrolein underlies the importance of the hydrogen-abstraction mechanism in photooxidation of allyl methyl sulfide (AMS).

This work explores theoretically the gas phase oxidation of allyl methyl sulfide (AMS, H2CCHCH2SCH3) initiated by •OH radicals, focusing on the H-abstraction pathway at the M06-2X-D3/aug-cc-pVTZ and MN15/aug-cc-pVTZ levels of theory (m06Tz and mn15Tz). The formation of a prereactive complex (PRC) is involved in H-abstraction processes with two potential directions of approach for the OH radical, denoted as “α” and “β”. The PRCs, demonstrate increased reactivity, primarily due to the interaction between the sulfur atoms and the hydroxyl hydrogen. A scheme for the H-abstraction mechanism that supports the experimentally identified products and predicts the formation of some S-containing low volatility products is proposed. The comparison of the potential energy surface (PES) between the double bond addition and H-abstraction paths in the AMS molecule shows that at the m06Tz level of theory, the H-abstraction on C3 and the addition to C1 have nearly the same profile of energy, while at the mn15Tz level, the minimum energy channel is the addition to C1. The theoretical rate coefficient for each reaction channel was calculated, considering the formation of a PRC prior to reaching the transition state of each channel and assuming thermal equilibrium between reactants and the PRC. The rate constants were calculated in a multi-TS/multi-conformer way at the SVECV-f12/m06Tz and SVECV-f12/mn15Tz levels of theory. The SVECV-f12 method is consistent in its predictions in both systems and exhibits only minor deviations from the experimental rate constants. Despite some specific differences due to the DFT method supporting the SVECV-f12 calculations, both methodologies predict a significant H-abstraction contribution in the AMS + OH gas phase reaction, which explains the high formation yield for acrolein determined experimentally.

An Optimized Point Multiplication Strategy in Elliptic Curve Cryptography for Resource-Constrained Devices

Elliptic curve cryptography (ECC) is widely acknowledged as a method for implementing public key cryptography on devices with limited resources thanks to its use of small keys. A crucial and complex operation in ECC calculations is scalar point multiplication. To improve its execution time and computational complexity in low-power devices, such as embedded systems, several algorithms have been suggested for scalar point multiplication, with each featuring different techniques and mathematical formulas. In this research, we focused on combining some techniques to produce a scalar point multiplication algorithm for elliptic curves over finite fields. The employed methodology involved mathematical analysis to investigate commonly used point multiplication methods. The aim was to propose an efficient algorithm that combined the best computational techniques, resulting in lower computational requirements. The findings show that the proposed method can overcome certain implementation issues found in other multiplication algorithms. In certain scenarios, the proposed method offers a more efficient approach by reducing the number of point doubling and point addition operations on elliptic curves using the inverse of the targeted point.

Phenylpropynones as Selective Disulfide Rebridging Bioconjugation Reagents.

Simple 1-phenylpropynones undergo a selective double thia-Michael addition with thiols in buffered media, yielding an interesting dithioacetal linkage joining two thiols. The reactivity of various Michael-alkyne reagents is compared in this chemoselective, atom economical, and non-oxidative cross-linking of two thiols. The stability and chemical reactivity of the dithioacetal links are studied, and the utility of the disulfide targeting bioconjugation methodology is shown by the selective rebridging of native cyclic peptides after the reductive cleavage of their disulfide bridge.

Correction: High-precision measurement of Cd isotopes in ultra-trace Cd samples using double spike-standard addition MC-ICP-MS

Correction for ‘High-precision measurement of Cd isotopes in ultra-trace Cd samples using double spike-standard addition MC-ICP-MS’ by Hui Chang et al., J. Anal. At. Spectrom., 2023, 38, 950–962, https://doi.org/10.1039/D3JA00047H.

Phosphine-catalyzed (3+3) annulation of cinnamaldehyde-derived Morita-Baylis-Hillman carbonates with dinucleophiles.

The phosphine-catalyzed (3+3) annulation reaction of cinnamaldehyde-derived Morita-Baylis-Hillman (MBH) carbonates with 1,3-dicarbonyl compounds as dinucleophiles has been developed, giving hexahydrochromenone derivatives in high yields with moderate to good diastereoselectivities. The reaction worked through double conjugate addition of 1,3-dicarbonyl compounds to the phosphonium intermediates generated from the cinnamaldehyde-derived MBH carbonates.

Synthesis of dispiro-orthoester via an acetal oxo-carbenium ion.

The first dispiro orthoester via a spiroacetal oxo-carbenium ion is presented. Oxidative dearomatization of phloretic esters results in a bifunctional electrophilic spiroacetal oxo-carbenium ion, which undergoes a double nucleophilic addition by diol delivering a range of unusual dispiro-orthoesters with an excellent diversity.