Carbon Double Bond Research Articles

Formation of Carbon–Carbon Double Bond between Cp Ligand and Alkenyl Carbon of Titanacyclopentenes

AbstractReactions of bis(cyclopentadienyl)titanacyclopentenes with BiI3 gave coupling products of one Cp ligand and the alkenyl carbons in moderate yields. An NMR study of the tetracyanoethylene (TCNE) adduct of the product showed that the coupled Cp ring and the alkenyl carbons were connected by one carbon–carbon double bond. This is in sharp contrast to coupling reactions of one Cp ligand with the diene moiety in bis(cyclopentadienyl)titanacyclopentadienes, where two carbon–carbon single bonds were formed between those two components to give dihydroindenes or spiro compounds.

Cyclization Strategies in Carbonyl–Olefin Metathesis: An Up-to-Date Review

The metathesis reaction between carbonyl compounds and olefins has emerged as a potent strategy for facilitating swift functional group interconversion and the construction of intricate organic structures through the creation of novel carbon–carbon double bonds. To date, significant progress has been made in carbonyl–olefin metathesis reactions, where oxetane, pyrazolidine, 1,3-diol, and metal alkylidene have been proved to be key intermediates. Recently, several reviews have been disclosed, focusing on distinct catalytic approaches for achieving carbonyl–olefin metathesis. However, the summarization of cyclization strategies for constructing aromatic heterocyclic frameworks through carbonyl–olefin metathesis reactions has rarely been reported. Consequently, we present an up-to-date review of the cyclization strategies in carbonyl–olefin metathesis, categorizing them into three main groups: the formation of monocyclic compounds, bicyclic compounds, and polycyclic compounds. This review delves into the underlying mechanism, scope, and applications, offering a comprehensive perspective on the current strength and the limitation of this field.

Toward new applications of terpenes in polymeric materials: Synthesis and characterization of myrcene‐modified unsaturated polyester resins

Abstractβ‐Myrcene, a terpenic monomer, holds potential for developing sustainable polymer‐based materials with enhanced properties. This study examines the synthesis of a myrcene‐based monomer and its incorporation into unsaturated polyesters, focusing on polymerization, curing, and final properties. Unsaturated polyesters were synthesized with varying myrcene‐based monomer content (6, 12, and 24 mol%), phthalic anhydride, maleic anhydride, propylene glycol, ethylene glycol, and diethylene glycol. Polymerization achieved conversion values of 0.92–0.93, resulting in polyesters with molar masses between 1400 and 1700 g mol−1 and dispersity indices of 2.0 to 2.3. Nuclear magnetic resonance (1H NMR) demonstrated short branch formation in myrcene‐modified polyesters and a high maleate‐to‐fumarate isomerization rate (92.66%–95.7%), affecting carbon–carbon double bonds per polyester mole (2.27 to 4.28) and final resin performance. Rheological analysis in a styrene solution (70/30 wt%) indicated shear‐thinning behavior, with viscosities ranging from 0.59 to 3.8 Pa·s, suggesting branching affects chain entanglement. Differential scanning calorimetry (DSC) revealed decreased curing enthalpy with increasing myrcene content, and it was inferred that myrcene's double bonds did not participate in curing. Glass transition temperatures of cured polyesters (70–107 °C) correlate with enthalpy trends. Thermal stability of myrcene‐modified polyesters is similar to the reference polyester, highlighting myrcene's potential as a sustainable monomer for customizable unsaturated polyesters.

Asymmetric Alkylative Difunctionalization of Carbon–Carbon Double Bonds by Aliphatic C─H Bond Activation

AbstractThis paper highlights the latest advancements in asymmetric alkylative difunctionalization of carbon–carbon double bonds by utilizing aliphatic C─H substrates as alkyl radical precursors. By integrating different hydrogen atom transfer (HAT) processes with various transition metal catalytic systems, various alkane substrates can be efficiently converted into corresponding alkyl radicals, which then participate in radical additions to carbon–carbon double bonds followed by stereoselective functionalizations with a third component. These strategies leverage inexpensive, abundant, and readily available alkane feedstocks to rapidly construct complex chiral molecules, demonstrating high step and atom economy. This paper focuses on recent progress and applications in this area, provides a comprehensive perspective on current developments, and suggests future directions in alkane‐involved asymmetric transformations.

Tow-way regulation strategy for in-situ electropolymerization additives coordinated by double bonds and boric acid groups in lithium secondary batteries

The stability and cycle life of the cathode material directly affect the electrochemical performance of the secondary battery, and the dendrite problem of the anode material greatly destroys its safety. To solve the above problems, here we report a small organic molecule monomer, 2,2-dimethylvinylboronic acid (DEBA) containing carbon–carbon double bonds and boric acid groups as electrolyte additive for lithium secondary battery. The unsaturated carbon–carbon double bonds in DEBA can undergo in-situ electropolymerization during the electrochemical process, forming a polymer network. The electron-deficient boron element can easily combine with the electron-rich lithium salt anion to form a B-F bond. It can promote the transport rate of Li+, alleviate the Li+ concentration gradient at the interface, and achieve uniform and dense deposition on the Li metal surface. The Li//graphite and Li//LiFePO4 half-cell experiments show that DEBA has an excellent tow-way regulation effect. This rationally designed dual-functional electrolyte additive provides a broad prospect for future electrolyte engineering.

Multireference calculations on bond dissociation and biradical polycyclic aromatic hydrocarbons as guidance for fractional occupation number weighted density analysis in DFT calculations

This study explores open-shell biradical and polyradical molecular compounds based on extended multireference (MR) methods (MR-configuration interaction with singles and doubles (CISD) and MR-averaged quadratic coupled cluster (AQCC) approach) using the numbers of unpaired densities NU. These results were used to guide the analysis of the fractional occupation number weighted density (FOD) calculated within the finite temperature (FT) density functional theory (DFT) approach. As critical test examples, the dissociation of carbon–carbon (CC) single, double and triple bonds and a benchmark set of polycyclic aromatic hydrocarbons (PAHs) have been chosen. By examining single, double, and triple bond dissociations, we demonstrate the utility and accuracy but also limitations of the FOD analysis for describing these dissociation processes. In significant extension of previous work (Phys Chem Chem Phys 25: 27380–27393), the assessment of FOD applications for different classes of DFT functionals was performed examining the range-separated functionals ωB97XD, ωB97M-V, CAM-B3LYP, LC-ωPBE, and MN12-SX, the hybrid (M06-2X) functional and the double hybrid (B2P-LYP) functional. In all cases, strong correlations between NFOD and NU values are found. The major task was to develop a new linear regression formula for range-separated functionals allowing a convenient determination of the optimal electronic temperature Tel for the FT-DFT calculation. We also established an optimal temperature for the semiempirical extended tight-binding GFN2-xTB method. These findings significantly broaden the applicability of FOD analysis across various DFT functionals and semiempirical methods.

Identification and quantitation of carbon–carbon double bond isomers of fatty acid in livestock and poultry meat

Livestock and poultry meat is one of the main consumption sources of fatty acids (FAs) in China. FAs are the main component of lipids and essential nutrients for the human body. The location of carbon–carbon double bond (CC) in unsaturated fatty acids (UFAs) significantly affects the nutrition and flavor quality of meat products. This study established an analytical method for identifying the CC positions of UFAs based on the Paternò-Büchi (PB) reaction using ultra-high performance liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOF). The FA extract was derivatized with 2-acetylpyridine under ultraviolet light at 254 nm. The derivatized FA was then analyzed using targeted MS/MS mode in positive electrospray ionization. Limits of detection (LOD) and limits of quantitation (LOQ) of 21 UFAs were 0.004–0.680 and 0.013–2.267 μg/L, respectively. Furthermore, for the diagnostic ions at the same functional group terminal fragmented from derivatives of FA CC isomers, the abundance ratio was linear with that of the corresponding content, which could be applied to non-targeted screening of CC positions in FAs. Based on this method, a total of 28 UFAs were screened in five types of livestock and poultry meats in this study. Among them, four isomers of C17:1, four of C18:1, two of C18:2, two of C20:3 and two of C22:5 were identified. The precise identification and quantitation of the double bond positions of fatty acids will be of great significance for the exploration of the nutritional components in livestock and poultry meat.

Water sorption behavior of poly(norbornene)-based anion exchange polyelectrolytes: Experiments and simulation

Poly(norbornene)s (PNBs) are great potential candidates for anion exchange polyelectrolytes (AEPs), however, PNBs-based AEPs usually suffer from excessive water sorption. Herein, the underlying mechanism behind high water sorption was proposed by using the quaternized PNBs as a model AEP. With a moderate ionic content of 2.15 mmol/g, the hydrogenated AEP has a high water uptake of 253 % at 25 °C, which is caused by heterogeneous quaternization and weak interchain interactions. When the brominated AEP was immersed in trimethylamine aqueous (TMA/H2O) solution, TMA penetrates tightly packed polymer chains, seriously destroying vdW interchain interactions. Subsequently, the quaternized cationic groups induce spontaneous water sorption. Although ionic moieties possess strong interchain electrostatic interactions, the solid AEPs restrict polymer chains to form highly cohesive domains for resisting water sorption. Additionally, carbon–carbon double bonds in the PNBs preferentially interact with TMA/H2O, further increasing water uptake. This work provides theoretical guidance for preparing high-performance AEPs based on all-hydrocarbon aliphatic backbones.

Multifunctional and immunoregulatory microenvironment-responsive hydrogel for whole course management of infected diabetic wounds

Infective diabetic wounds can significantly delay healing and pose severe infection risks. The process of infective diabetic wounds healing (DWH) are not only re-epithelialization and angiogenesis but also anti-bacterial, hair follicles regeneration and nerve growth. In this study, a stable dynamic hydrogel system was formulated by incorporating dynamic borate easter bond and carbon–carbon double bond, which based on tannic acid (TA) − acrylic phenyl boric acid (APBA) and acrylamide (AM). Subsequently, a hydrogel (ATAN-Met) was obtained by modifying the antibacterial ammonium cationic (N+) and loading metformin (Met). This system demonstrated impressive wet adhesion, self-healing, wearable and peelable properties, responding to glucose/reactive oxygen species (ROS) for drug release. In vitro and vivo experiments illustrated that ATAN-Met recruited mesenchymal stem cell (MSC), facilitating interaction between MSC and neural cells, regulating macrophage polarization, and modulating the diabetic wound microenvironment while exhibiting anti-bacterial property, ultimately leading to re-epithelialization and neurovascular-hair follicles regeneration. RNA and metabolomic sequencing indicated that ATAN-Met activate the Hippo pathway, inhibit the TNF pathway, and regulate wound metabolism to improve the diabetic wound microenvironment. These results suggest that the microenvironment-responsive ATAN-Met hydrogel shows considerable potential for the whole course management of infective DWH.

One‐Pot Cascade Reaction from Epoxide to Carboxylic Acids Using Bifunctional Fe‐ZSM‐5

AbstractThe quest for sustainable synthesis of carboxylic acids has led to the exploration of innovative routes and catalysts for the oxidative cleavage of carbon−carbon double bonds, prevalent in bio‐derived molecules. This process involves multiple steps including epoxidation, hydrolysis and vicinal diol cleavage, often catalysed by unsustainable homogeneous or noble‐metal catalysts. In this study, we present the utilization of Fe‐ZSM‐5 as a versatile bifunctional catalyst capable of catalysing both hydrolysis and vicinal diol cleavage steps, utilizing propylene oxide as model compound and H2O2 as oxidizing agent. The prepared Fe‐ZSM‐5 features the zeolite intrinsic Lewis and Brønsted acidity functions, essential for the hydrolysis step, as well as high fractions of monomeric FeOx species, crucial for the subsequent vicinal diol cleavage, leading to streamlined carboxylic acids formation in a one‐pot, two‐step process. Moreover, by combining Fe‐ZSM‐5 with TS‐1, renowned for its epoxidation activity, we demonstrate the complete cascade reaction in one pot, under mild conditions, starting from ethylene. Our study expands the utility of cost‐effective zeolite‐based catalysts enriched with abundant Fe metal for the one‐pot oxidative cleavage of C=C double bonds, offering a promising pathway towards sustainable carboxylic acid synthesis.

Tuning the Permeation Properties of Poly(1‐trimethylsilyl‐1‐propyne) by Vapor Phase Infiltration Using Trimethylaluminum

AbstractVapor phase infiltration (VPI) has emerged as a promising tool for fabrication of novel hybrid materials. In the field of polymeric gas separation membranes, a beneficial impact on stability and membrane performance is known for several polymers with differing functional groups. This study for the first time investigates VPI of trimethylaluminum (TMA) into poly(1‐trimethylsilyl‐1‐propyne) (PTMSP), featuring a carbon–carbon double bond as functional group. Saturation of the precursor inside the polymer is already attained after 60 s infiltration time leading to significant densification of the material. Depth profiling proves accumulation of aluminum in the polymer itself, but a significantly increased accumulation is visible in the gradient layer between polymer and SiO2 substrate. A reaction pathway is proposed and supplemented by density‐functional theory (DFT) calculations. Infrared spectra derived from both experiments and simulation support the presented reaction pathway. In terms of permeance, a favorable impact on selectivity is observed for infiltration times up to 1 s. Longer infiltration times yield greatly reduced permeance values close or even below the detection limit of the measurement device. The present results of this study set a strong basis for the application of VPI on polymers for gas‐barrier and membrane applications in the future.

Investigating the mechanism of Bacillus amyloliquefaciens YUAD7 degrading aflatoxin B1 in alfalfa silage using isotope tracing and nuclear magnetic resonance methods

BackgroundFungal toxins are highly toxic and widely distributed, presenting a considerable threat to global agricultural development. Addressing the issue of aflatoxin B1 (AFB1) contamination in feed, it is crucial to ascertain the effectiveness and mechanisms of microbial strains in degradation.ResultsThis study used isotope tracing and nuclear magnetic resonance (NMR) to investigate the degradation products of Bacillus amyloliquefaciens YUAD7 in complex substrates. By tracing 14C34-AFB1 and utilizing NMR, ultra-performance liquid chromatography–quadrupole time-of-flight/mass spectrometry (UPLC–Q-TOF/MS) purification and identification techniques, it was confirmed that AFB1 was degraded by YUAD7 into C12H14O4, C5H12N2O2, C10H14O2, and C4H12N2O, effectively removing 99.7% of AFB1 (100 μg/kg) from alfalfa silage. YUAD7 targeted the ester bond in the vanillin lactone ring structure, the ether bond in the furan ring structure, and the unsaturated carbon–carbon double bond in the furan ring structure during AFB1 degradation, disrupting the toxic sites responsible for AFB1's carcinogenic, teratogenic, and mutagenic effects and achieving biodegradation. Moreover, B. amyloliquefaciens YUAD7 transformed AFB1 through processes like hydrogenation, enzyme modification, and the loss of the -CO group while also being associated with metabolic pathways such as alanine, aspartate, glutamate metabolism, glutathione metabolism, cysteine and methionine metabolism, and pentose and glucuronate interconversions.ConclusionsThe utilization of isotope tracing allowed for rapid identification of degradation products in complex substrates, while NMR elucidated the structures of these products. This deepens our understanding of AFB1 biodegradation mechanisms, providing technical support for the practical application of these bacteria in degradation, and new insights into studying the biological degradation mechanism. B. amyloliquefaciens YUAD7 can be used as a potential strain for degrading AFB1 in large-scale silage.Graphical

Effect of number of intramolecular double bonds on photophysical properties and ESIPT processes for Cha-NH2 and its derivatives: A theoretical study

In recent years, the research on excited-state intramolecular proton transfer (ESIPT) reactions has aroused increasingly attention theoretically and experimentally. For a deep exploration, we designed three derivatives of Cha-NH2 with different numbers of carbon–carbon double bonds: Cha-NH2-1, Cha-NH2-2, and Cha-NH2-3. Using density functional theory and time-dependent density functional theory methods, we systematically studied the photophysical properties and ESIPT processes of Cha-NH2 and its derivatives. Detailed analysis revealed that the number of carbon–carbon double bonds within the molecule has a significant impact on the ESIPT behavior and spectral properties of Cha-NH2 and its derivatives. Specifically, as the number of carbon–carbon double bonds increases, the strength of intramolecular hydrogen bond is gradually weakened, leading to a red shift in the spectrum and a increase in the forward energy barrier for ESIPT, which is unfavorable for the occurrence of the ESIPT reaction. Therefore, this finding opens up broad application prospects for the adjustment and optimization of future ESIPT process.

Styrene-butadiene-styrene block copolymer modified bitumen with ultraviolet absorbent intercalated layered double hydroxide: Compatibility and anti-ageing properties

2-hydroxy-4-methoxybenzophenone-5-sulfonic acid (ultraviolet absorbent, BP) intercalated layered double hydroxide (LDH) was synthesized to enhance the anti-ageing properties of styrene–butadiene–styrene block copolymer (SBS) modified bitumen (SMB). X-ray diffraction and UV–vis spectroscopy indicated that BP has been successfully substituted into LDH interlamination, and BP intercalated LDH (BP-LDH) exhibited better UV absorptive capacity than LDH. Then, the physical and rheological properties, chemical structure of BP-LDH and LDH modified SMB before and after ageing were comprehensively studied. Compared with LDH, BP-LDH possessed the smaller difference in solubility parameters (δ) and the stronger interaction energy (Einter) with SMB, resulting in the better compatibility of BP-LDH modified SMB. The high-temperature stability of SMB was promoted with the addition of BP-LDH or LDH, especially BP-LDH. After ageing, the temperature susceptibility, low-temperature anti-cracking and anti-fatigue cracking of SMB were deteriorated, the oxygen-containing groups (C = O and S = O) in SMB noticeably increased and carbon–carbon double bond (C = C) concurrently decreased. LDH could mitigate the ruin of ageing on the performance and chemical structures of SMB, and strengthen the anti-ageing performance. Furthermore, BP intercalated modification could further significantly heighten the performance of LDH.

Study of UV-cured tung oil-based polyalcohol resin with isophorone diisocyanate as crosslinker

Petroleum-based resins are associated with increasing energy demands and biodegradability issues. Resins produced from biomass raw materials are a suitable alternative and hold significant potential across various applications, including the manufacture of molding materials, oil-based resins, and adhesives. Particularly in the field of coatings, biomass-based resins are recognized for their environmental friendliness and renewability, although there remains room for improvement in terms of strength and curing speed compared with petroleum-based resins. In this study, we developed a high-strength tung oil-based polyurethane photocurable resin (TOPP). To produce the resin, tung oil was first converted into tung oil polyol, and then acrylic ester along with isophorone diisocyanate was used as a bridging agent to confer photocuring properties. Analysis via infrared and nuclear magnetic resonance spectroscopy confirmed the TOPP structure and demonstrated the reaction of carbon–carbon double bonds to form polyol. TOPP exhibited impressive mechanical properties, including a tensile strength of 21.02 MPa and an elastic modulus of 954.63 MPa, achieved through the optimization of the amount of hydroxyethyl methacrylate added. Additionally, TOPP exhibited excellent hydrophobicity with a maximum water contact angle of 88.78° and a low thermal conductivity of 0.26 W·(mK)−1. As a wood coating, TOPP significantly enhanced resistance to oil and improved waterproof performance. The curing speed was notably accelerated without emissions of volatile solvents, which demonstrates the substantial potential of the resin for coating applications on wooden products, particularly in the furniture industry.

An atom economy polyamide elastomer derived from polyether amine‐based bis‐acrylamide and dithiol monomer and synthesized by thiol‐Michael addition click reaction

AbstractTraditional polyamide elastomer synthesis via polycondensation of diamines and dicarboxylic acids involves high energy use and by‐product mass loss. Here, we present a novel method using thiol‐Michael addition click chemistry to produce these elastomers under mild conditions, marking the first use of this strategy. The polymerization involves coupling bis‐acrylamide (BAA) with 3,6‐dioxa‐1,8‐octanedithiol (DODT), catalyzed by 1,5‐diazabicyclo[4.3.0]non‐5‐ene (DBN). BAA is synthesized from polyetheramine and acryloyl chloride, creating a compound with amide groups and carbon double bonds at chain ends. These double bonds' electron‐withdrawing effect facilitates the click reaction efficiently, avoiding high energy and mass loss. The resulting polymers have a molecular weight of approximately 10,000 g/mol, verified by 1H NMR and FTIR spectroscopy, which show amide group presence. SAXS and AFM confirm nanophase separation of these groups. Tensile strength ranges from 0.235 to 0.542 MPa, decreasing with lower polyetheramine content but still showing notable elasticity. This method's low energy use, no mass loss, and good mechanical properties make it promising for developing high‐performance polyamide plastics and elastomers, appealing to researchers in both academia and industry.Highlights High elasticity, softness, and high tensile polyamide elastomer. Thiol‐Michael addition click reaction conforms to atomic economy. Long molecular chain contains extraordinary evolution of hydrogen bonding.

Step-growth irreversible deactivation radical polymerization: synergistic developments with chain-growth reversible deactivation radical polymerization

Abstract Recent advances in chain-growth reversible deactivation radical polymerization (CG-RDRP), i.e. the so-called “living radical polymerization”, have synergistically developed step-growth radical polymerizations via controlled formation of radical species from covalent bonds followed by irreversible deactivation of the resulting radical species. The monomers for radical polyaddition are thus designed to possess carbon–halogen or thioester bonds, which can generate radical species in the presence of transition metal catalysts and radical initiators, as well as carbon‒carbon double bonds, which will irreversibly form carbon–halogen or thioester bonds. Radical polycondensations are achievable via radical coupling reactions of carbon-centered radicals generated from carbon–halogen bonds or radical quenching reactions with nitroxides. Furthermore, radical addition-condensation polymerizations are achieved by a sequence of reactions, i.e. the formation of radical species from carbon–halogen bonds, radical addition to nitroso or thiocarbonylthio compounds, and coupling or quenching reactions with the resulting stable radical. These step-growth irreversible deactivation radical polymerizations (SG-IDRP) enable the synthesis of a variety of polymers, such as polyethers, polyesters, polyamides, and polyimides, which have aliphatic, aromatic, polar, and degradable groups in their main chains. Sequence-regulated vinyl polymer structures can also be constructed by designing monomers. Combinations with CG-RDRPs further lead to unique hybrid block, multiblock, graft, hyperbranched, and network polymers.

How the addition of atomic hydrogen to a multiple bond can be catalyzed by water molecules.

Observational data show complex organic molecules in the interstellar medium (ISM). Hydrogenation of small unsaturated carbon double bond could be one way for molecular complexification. It is important to understand how such reactivity occurs in the very cold and low-pressure ISM. Yet, there is water ice in the ISM, either as grain or as mantle around grains. Therefore, the addition of atomic hydrogen on double-bonded carbon in a series of seven molecules have been studied and it was found that water catalyzes this reaction. The origin of the catalysis is a weak charge transfer between the π MO of the unsaturated molecule and H atom, allowing a stabilizing interaction with H2O. This mechanism is rationalized using the non-covalent interaction and the quantum theory of atoms in molecules approaches.

One‐Pot Access to Sulfonyl 2,3‐Diarylnaphthalenes via tBuOK‐Mediated Benzannulation of o‐Bis‐sulfonylmethyl Arenes with Diarylacetylenes

AbstractOne‐pot access to sulfonyl 2,3‐diarylnaphthalenes was developed via tBuOK‐mediated (4+2) benzannulation of o‐bis‐sulfonylmethyl arenes, employing diverse diarylacetylenes. A plausible mechanism is proposed and discussed. The advantages of the system include the use of inexpensive reagents, wide substrate scope, and mild reaction conditions. The synthetic route allows for the formation of two carbon–carbon double bonds (C=C).

A Review of Chemical Modification of Vegetable Oils and Their Applications

In order to cope with the shortage of non-renewable energy and the increasingly environmental pollution, sustainable vegetable oils, as competitive alternatives, have widely been held in the good graces of the researchers. Vegetable oils are suitable for a wide range of applications such as biofuels and biodiesel. However, the development of vegetable oils is limited due to the characteristics of unsatisfactory oxidation stability and poor cold-flow properties. Chemical modification is considered as an effective solution to enhance the performance. The research progress of the chemical modification methods and applications of vegetable oils in recent years are summarized in this review. Reducing the content of carbon–carbon double bonds and increasing the degree of saturation are the keys to improve the physicochemical properties of vegetable oils. The prospects for the development direction and challenges of vegetable oils are proposed. Future research may focus on the use of multifunctional catalysts to optimize reaction conditions or to introduce active groups with lubricating properties in epoxidation reactions and explore the combination of chemical and auxiliary methods.