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The double-ion chamber (DIC) method has been used to measure photoabsorption cross sections in the ionization region of the sample gas. In this study, we introduce a method to extend the wavelength region of the DIC measurements beyond the ionization threshold wavelength by using the photoion currents from the impurities in the sample gas. To verify this method, the photoabsorption cross sections of C2H2 (ionization threshold wavelength λth = 108.8 nm) have been measured from 105 to 137 nm. The natural impurity, acetone (λth = 127.8 nm), contained 1% in high-purity grade acetylene (C2H2) sample gas, allowing for measurements in the non-ionizing region of C2H2 up to 127.7 nm. By adding 1% benzene (λth = 134.6 nm) in the sample gas, measurements were possible even further, to 134.5 nm. This new method enables the measurement of the photoabsorption cross section by photoions that are produced from the impurities in the sample gas in a substantial amount. The current measurement methodology aligns well with the previous measurements of Suto and Lee [Suto and Lee, J. Chem. Phys. 80, 4824 (1984)]. [ABSTRACT FROM AUTHOR]

The random-phase approximation (RPA) includes a subset of higher than second-order correlation-energy contributions, but stays in the same complexity class as the second-order Møller–Plesset perturbation theory (MP2) in both Gaussian-orbital and plane-wave codes. This makes RPA a promising ab initio electronic structure approach for the binding energies of molecular crystals. Still, some issues stand out in practical applications of RPA. Notably, compact clusters of nonpolar molecules are poorly described, and the interaction energies strongly depend on the reference single-determinant state. Using the many-body expansion of the binding energy of a crystal, we investigate those issues and the effect of beyond-RPA corrections. We find the beneficial effect of quartic-scaling exchange and non-ring coupled-cluster doubles corrections. The nonadditive interactions in compact trimers of molecules are improved by using the self-consistent Hartree–Fock orbitals instead of the usual Kohn–Sham states, but this kind of orbital input also leads to underestimated dimer energies. Overall, a substantial improvement over the RPA with a renormalized singles approach is possible at a modest quartic-scaling cost, which encourages further research into additional RPA corrections. [ABSTRACT FROM AUTHOR]

We demonstrate massively parallel spectroscopic measurements of 12C2H2 using an optical frequency comb. This allows for the rapid and simultaneous estimation of self-broadening and self-shifting of more than 50 optical transitions between 1512 and 1538 nm. The use of a temperature-controlled sealed gas cell allows us to measure both pressure- and temperature-mediated broadening and shifting. We present the results for the pressure-mediated self-broadening and self-shifting coefficients for 59 optical lines that make up the v1 + v3 combination band and a selection of hot bands. Our ability to measure the broadening of numerous transitions allows for the confirmation of prior work that shows that there is no measurable vibrational dependence across all acetylene bands, despite the strong dependence of the broadening coefficient on the rotational number. We also present an extensive measurement of the temperature dependence of the self-broadening for each of these 59 lines. This work shows the revolutionary power afforded by the frequency combs for rapid generation of large datasets related to thermodynamic variations of the key spectroscopic parameters of important gases. [ABSTRACT FROM AUTHOR]

The hydrogenation of acetylene to ethylene is of great industrial interest. Achieving both high selectivity and high conversion of acetylene to ethylene via semi‐hydrogenation is quite challenging. Bimetallic catalysts offer opportunities to selectively control reaction pathways by altering the electronic and geometric properties of active sites on the catalyst surface. Recent advancements in the synthesis of bimetallic catalysts enabled the creation of random alloys, intermetallics, segregated structures, or single‐site alloys with precision. These catalysts could be tailored for semi‐hydrogenation of acetylene by tuning the features including adsorption energy, active site isolation, and the d‐band center. Modern machine learning tools are also helpful for catalyst design. In this article, an overview of the conceptual advances in the design aspects of bimetallic catalysts, advances and challenges involved in the acetylene semi‐hydrogenation, has been presented. [ABSTRACT FROM AUTHOR]

2D carbon allotropes with moderated electronic bandgaps are highly desirable for next‐generation carbon‐based nanoelectronics beyond graphene. Herein, the structural and electronic properties of bilayer α‐graphyne have been systematically investigated by using first‐principles calculations. Consequently, in addition to typical van der Waals (vdW) stacks of single‐layer α‐graphyne, new 2D carbon allotropes with purely sp2 or sp3 hybridizations can be achieved, arising from the absence of intralayer acetylene linkages during structural relaxation. Compared to the Dirac semimetallic behavior of monolayer α‐graphyne, the electronic structure of vdW bilayer α‐graphyne can be further modulated by stacking patterns, yet retains metallic characteristics. In contrast, intrinsic semiconducting characteristics can be observed in the proposed new 2D carbon allotropes with tunable bandgaps dependent on the in‐plane biaxial strain. Correspondingly, a pristine 2D carbon sheet with only sp2 hybridization exhibits a promising direct bandgap of 1.062 eV, while the sp3‐hybridized carbon network possesses an indirect bandgap of 1.708 eV, which can be further converted to the direct type under small compressive strains, implying great potential in future carbon‐based nanoelectronic applications beyond graphene. Also, this work provides a new approach for developing novel carbon allotropes via the vertical stacking of graphyne with acetylenic linkages. [ABSTRACT FROM AUTHOR]

Transition metal carbide shows excellent performance in selective hydrogenation of acetylene, however, the carburization of Pd-based intermetallic compounds remains infeasible. Here we report the successful synthesis of an unprecedented Pd3ZnCx intermetallic carbide, via co-infiltration of zinc and carbon in one-step carburization by syngas. Utilizing state-of-the-art in situ characterizations and theoretical calculation, we unveil the dynamic evolution of Pd3ZnCx during carburization, forming a Pd3Zn like cubic phase carbide structure. A unique transitional state (Pdt) with low content of Zn/C co-infiltration is clearly identified facilitating phase transition and sustain incorporation of carbon and zinc at elevated temperatures. The Pd3ZnCx carbide shows by far the best catalytic performance in the selective hydrogenation of acetylene with a high selectivity (>90%) even at a high H2/C2H2 ratio. Our results therefore provide a co-infiltration strategy and dynamic insights for the one-step synthesis of Pd based intermetallic carbides, towards high-performance intermetallic compound for selective hydrogenation of acetylene. Transition metal carbides exhibit outstanding performance in the selective hydrogenation of acetylene, but carburizing Pd-based intermetallic compounds has been challenging. Here, the authors present a successful synthesis of Pd3ZnCx intermetallic carbide for selective hydrogenation of acetylene through a one-step co-infiltration of zinc and carbon using syngas. [ABSTRACT FROM AUTHOR]

Acetylene/polyynes −(C≡C−)n and cumulenes =(C=)n are connectors widely used for the realization of one‐dimensional (1D) π‐conjugates. Although both π‐moieties are constituted by sp carbon atoms, their different bond connectivity confers distinct physicochemical properties to the resulting systems. In this context, while many acetylene/polyyne‐ and cumulene‐based derivatives have been prepared and studied, no reports have tackled the possibility to reversibly alter the acetylene/polyyne‐cumulene electronic character of these derivatives using mild conditions. Herein, we present a novel approach to enhance the cumulene character of 1D acetylene‐based conjugates consisting in the preparation of derivatives featuring an acetylene moiety connecting two pro‐diradicaloid species, namely cyclopenta[h,i]aceanthrylene (CPA), at their pro‐radical positions. A thoughtful spectroscopic study of the prepared dimers, complemented by theoretical calculations, suggest a high π‐electronic delocalization of the pro‐diradicaloid CPAs through the central acetylene spacer upon the dimers’ planarization which, in turn, increases the cumulenic character of the acetylenic π‐bridge, a feature enhanced for one of the two dimers at low temperature and in methylcyclohexane due to an aggregation‐induced planarization process. We reckon that the proposed approach offers an interesting avenue towards the realization of 1D systems which cumulenic character of the acetylenic π‐connector could be altered in response to external stimuli. [ABSTRACT FROM AUTHOR]

The potential of acetylene is extremely high both in chemical industry and synthetic applications due to unsaturated nature and the smallest active C≡C unit. The production of many essential necessities is originated from acetylene; however, the formation of acetylene molecule requires a lot of energy. Currently, the access to acetylene is based on coal processing, methane reforming and calcium carbide hydrolysis. Recently, extensive research has been done to decrease the cost of acetylene. In this review, the routes to acetylene were highlighted, considering the energy consumption in kW ⋅ h/t of the product to evaluate the best approach. Since energy prices depend on various regions, the cost of the product is complicated. The manufacturing of acetylene is usually accompanied by formation of by‐products, which may be valuable or not. The review should help to identify current status and not overlook promising approaches. [ABSTRACT FROM AUTHOR]

The development of photosensitizers with extended π‐conjugation and spectral matching to sunlight and fluorescent light is crucial for achieving high power conversion efficiency (PCE) in dye‐sensitized solar cells (DSSCs). This study presents a series of novel anthracene‐based photosensitizers, AMO1–AMO4. This series has been designed with bulky modified Hagfeldt donors to suppress undesired molecular aggregation, double anthracene groups for enhanced π‐conjugation, acetylene groups for improved molecular planarity, and four distinct acceptors to fine‐tune their photophysical and electrochemical properties. The performance of the novel dyes in DSSCs is investigated using two copper redox shuttles, CuI/II(dmp)2 and CuI/II(dmodmbp)2. Among the investigated dyes, AMO2 mediated with CuI/II(dmodmbp)2 exhibits the highest power conversion efficiency (PCE) of 10.05% (JSC = 13.72 mA cm 2, VOC = 1.035 V, and FF = 0.71) under sunlight illumination and an outstanding PCE of 34.64% under T5 illumination (6000 lux). These achievements underscore the remarkable potential of anthracene‐bridged sensitized DSSCs in indoor and outdoor applications. [ABSTRACT FROM AUTHOR]

With the shortage of international oil resources and rising oil prices, the acetylene chemical industry has been revitalized. As an important basic raw material in the petrochemical industry, it can produce many chemical products and extend the acetylene production chain. Firstly, the production, conversion, and utilization of acetylene are outlined. Subsequently, this paper focuses on reviewing the core production process routes and the corresponding research progress in the acetylene production chain and points out the development trends of the domestic acetylene downstream conversion. Then, considering that acetylene is produced by calcium carbide technology in Ningdong and the extended downstream polyvinyl chloride industry chain is a large energy consumer and the focus of environmental safety monitoring, the entire process from coal-based calcium carbide acetylene production to polyvinyl chloride synthesis is elaborated from the perspective of process systems engineering. The resource utilization status and bottlenecks in the process are declared, and the direction of process improvement and optimization is proposed. Finally, the entire acetylene production chain is briefly analyzed and reviewed. [ABSTRACT FROM AUTHOR]

A new palladium‐based catalyst system modified with dibenzofuran (DBF) was developed for acetylene hydrochlorination. The optimal Pd‐DBF/SAC catalyst with the 0.5 wt% Pd loading and the 15 wt% DBF loading exhibits an elevated performance of 99.9% acetylene conversion and 99.9% vinyl chloride selectivity for more than 400 h. Characterization analysis and density functional theory (DFT) simulations revealed that the presence of oxygen‐containing DBF species of the Pd‐DBF/SAC catalyst prevents the reduction and loss of Pd species, inhibits the carbon deposition and enhances the HCl adsorbability, resulting in superior catalytic activity and stability for acetylene hydrochlorination. [ABSTRACT FROM AUTHOR]

Ambient-condition acetylene hydrogenation to ethylene (AC-AHE) is a promising process for ethylene production with minimal additional energy input, yet remains a great challenge due to the difficulty in the coactivation of acetylene and H2 at room temperature. Herein, we report a highly efficient AC-AHE process over robust sulfur-confined atomic Pd species on tungsten sulfide surface. The catalyst exhibits over 99% acetylene conversion with a high ethylene selectivity of 70% at 25 oC, and a record space-time yield of ethylene of 1123 molC2H4 molPd−1 h−1 under ambient conditions, which is nearly four times that of the typical Pd1Ag3/Al2O3 catalyst, and exhibiting superior stability of over 500 h. We demonstrate that the confinement of Pd-S coordination induces positively-charged atomic Pdδ+, which not only facilitates C2H2 hydrogenation but also promotes C2H4 desorption, thereby enabling a high conversion of C2H2 to C2H4 at room temperature while suppressing over-hydrogenation to C2H6. Ambient-condition acetylene hydrogenation to ethylene (AC-AHE) is a promising process for ethylene production yet remains a challenge. Here the authors report a highly efficient AC-AHE process over robust sulfur-confined atomic Pd species on tungsten sulfide surface, achieving over 99% conversion and 70% selectivity, with a record-breaking ethylene yield and excellent stability exceeding 500 h at 25 °C. [ABSTRACT FROM AUTHOR]

Researchers demonstrated that implementing new combustion technology and optimising fuel quantity results in a significant reduction in traditional fossil fuel usage and emission levels. The Reactivity Controlled Compression Ignition (RCCI) combustion strategy is one of the low temperature combustion technologies, and it is used to reduce the overall combustion temperature while also providing better combustion control. This study looks into RCCI combustion technology, which uses conventional diesel fuel as the high reactivity fuel (HRF) injected through the injector and acetylene gas as the low reactivity fuel (LRF) injected into the cylinder via a modified inlet manifold alongside air. The modified engine setup was tested for performance, emissions, and combustion under various load conditions, as well as different mass flow rates of acetylene gas, a low reactivity fuel that is injected with air. The flow field of the low reactivity fuel at the inlet manifold is analysed using the Computational Fluid Dynamics principle, which is used to determine the best flow rate for improving combustion quality. According to the simulation results, the optimal acetylene flow rate is 3 Litres Per Minute (LPM), and experimentation shows that at 3 LPM acetylene injection, the brake thermal efficiency (BTE) improves by about 3.2%, and emissions such as carbon monoxide (CO), hydrocarbon (HC), smoke intensity, and oxides of nitrogen (NOx) are reduced by about 35%, 17%, 10%, and 21%, respectively. [ABSTRACT FROM AUTHOR]

Electrocatalytic hydrogenation of acetylene to ethylene in aqueous electrolytes under ambient conditions faces efficiency and selectivity limitation due to the competitive formation of 1,3‐butadiene and hydrogen. In this study, the development of a  copper nanoparticle/FeNC composite catalyst is reported through a simple mechanical grinding approach that demonstrates remarkable performance, achieving a highest ethylene Faradaic efficiency of 97.7% at 180 mA cm−2 and selectivity of 92.6% at 200 mA cm−2. Experimental investigations reveal that Cu atoms serve as the active sites, and the integration of FeNC improves the specific surface area through its 2D nanosheet morphology. Further analysis utilizing in situ Raman measurements coupled with theoretical calculations confirms that FeNC accelerates water dissociation to provide abundant protons and improving their transfer, thereby suppressing 1,3‐butadiene formation and elevating acetylene selectivity. Notably, the integration of FeNC also transforms the desorption of *C2H4 into an exothermic process, further facilitating ethylene production. Overall, this study introduces a simple and innovative preparation approach of composite catalysts for selective ethylene synthesis, expanding the application scope of Cu‐based FeNC materials in various electrocatalytic hydrogenation reactions. [ABSTRACT FROM AUTHOR]

Achieving light-induced manipulation of controlled self-assembly in nanosized structures is essential for developing artificially dynamic smart materials. Herein, we demonstrate an approach using a non-photoresponsive hydrogen-bonded (H-bonded) macrocycle to control the self-assembly and disassembly of nanostructures in response to light. The present system comprises a photoacid (merocyanine, 1-MEH), a pseudorotaxane formed by two H-bonded macrocycles, dipyridinyl acetylene, and zinc ions. The operation of such a system is examined according to the alternation of self-assembly through proton transfer, which is mediated by the photoacid upon exposure to visible light. The host–guest complexation between the macrocycle and bipyridium guests was investigated by NMR spectroscopy, and one of the guests with the highest affinity for the ring was selected for use as one of the components of the system, which forms the host–guest complex with the ring in a 2:1 stoichiometry. In solution, a dipyridine and the ring, having no interaction with each other, rapidly form a complex in the presence of 1-MEH when exposed to light and thermally relax back to the free ring without entrapped guests after 4 h. Furthermore, the addition of zinc ions to the solution above leads to the formation of a polypseudorotaxane with its morphology responsive to photoirradiation. This work exemplifies the light-controlled alteration of self-assembly in non-photoresponsive systems based on interactions between the guest and the H-bonded macrocycle in the presence of a photoacid. [ABSTRACT FROM AUTHOR]

According to city road tests conducted during peak vehicle traffic hours, vehicle idle times constitute about 30-38% of the total running time. Therefore, when it comes to urban transportation, the fuel consumption and resulting exhaust emissions from passenger cars powered by internal combustion engines and constitute a large portion of the number of vehicles, become significant while idling. This study investigates the effects of using acetylene as fuel on the idling performance of a gasoline engine. Experiments conducted on a four-stroke, four-cylinder, water-cooled, spark-ignition automobile engine showed that using gasoline-acetylene mixtures and 100% acetylene instead of gasoline alone resulted in a decrease in carbon monoxide and hydrocarbon emissions and an increase in nitrogen oxide emission. Carbon monoxide emissions, which were 2.2% in gasoline operation, decreased to 1.1% and 0.7% with the addition of acetylene to gasoline at 100 and 150 g/h flow rates, respectively, while HC emissions, which were 895 ppm, became 576 ppm and 520 ppm. In experiments using 100% acetylene in the test engine, it was observed that there was a 96% reduction in carbon monoxide and hydrocarbon emissions and a 650% increase in nitrogen oxide emissions compared to running on gasoline. It was found that there was a 20.5% decrease in the energy flow to the engine. [ABSTRACT FROM AUTHOR]

Acetylene hydrogenation reactions (AHR) are typically carried out in fixed bed reactors (FBRs) with high diameter‐to‐particle diameter (D/d). In this study, first, a real catalyst bed was built using the discrete element method, and the suitability of the bed was assessed using empirical equations. Second, a discrete element method‐computational fluid dynamics (DEM‐CFD) model was developed using CFD in conjunction with the reaction mechanism to simulate the AHR in the FBR and was compared with the experimental results. The results show that the DEM‐CFD can well predict the 3D interactions of velocity, temperature, and species for different D/d. The results can provide favorable theoretical guidance for the optimization of FBR and process intensification. [ABSTRACT FROM AUTHOR]

Acetylene and methylacetylene are impurities commonly found in the raw materials used for the production of polymers such as polypropylene and polyethylene. Experimental evidence indicates that both acetylene and methylacetylene can decrease the productivity of the Ziegler-Natta catalyst and alter the properties of the resulting polymer. However, there is still a lack of understanding regarding the mechanisms through which these substances affect this process. Therefore, elucidating these mechanisms is crucial to develop effective solutions to this problem. In this study, the inhibition mechanisms of the Ziegler-Natta catalyst by acetylene and methylacetylene are presented and compared with the incorporation of the first propylene monomer (chain initiation) to elucidate experimental effects. The Density Functional Theory (DFT) method was used, along with the B3LYP-D3 functional and the 6-311++G(d,p) basis set. The recorded adsorption energies were −11.10, −13.99, and −0.31 kcal mol−1, while the activation energies were 1.53, 2.83, and 28.36 kcal mol−1 for acetylene, methylacetylene, and propylene, respectively. The determined rate constants were 4.68 × 1011, 5.29 × 1011, and 2.3 × 10−8 M−1 s−1 for acetylene, methylacetylene, and propylene, respectively. Based on these values, it is concluded that inhibition reactions are more feasible than propylene insertion only if an ethylene molecule has not been previously adsorbed, as such an event reinforces propylene adsorption. [ABSTRACT FROM AUTHOR]

The development of all kinds of covalent drugs had a major impact on the improvement of the human health system. Covalent binding to target proteins is achieved by so‐called electrophilic warheads, which are incorporated in the respective drug molecule. In the last decade, specifically acrylamides emerged as attractive warheads in covalent drug design. Herein, a straightforward palladium‐catalyzed hydroaminocarbonylation of acetylene has been developed, allowing a modular and diverse synthesis of bio‐active acrylamides. This general protocol features high atom efficiency, wide functional group compatibility, high chemoselectivity and proceeds additive free under mild reaction conditions. The synthetic utility of this protocol is showcased in the synthesis of ibrutinib, osimertinib, and other bio‐active compound derivatives. [ABSTRACT FROM AUTHOR]

A convenient method for the construction of 9,10‐diarylphenanthrenes through one‐pot multicomponent reactions of iodoarenes, o‐bromobenzoic acids, and calcium carbide is described. A series of target compounds are efficiently synthesized via Csp2−H activation and the simultaneous construction of five C−C bonds. The salient features of this method are the use of inexpensive and easy‐to‐handle solid alkyne source as an alternative of flammable and explosive gaseous acetylene. Meanwhile the use of commercially available substrates, wide functional tolerance, and simple workup procedure are also advantage of this protocol. In addition, the corresponding products can also be synthesized on gram scale. [ABSTRACT FROM AUTHOR]

The bottom‐up synthesis of carbon nanotubes (CNTs) is a long‐standing goal in synthetic chemistry. Producing CNTs with defined lengths and diameters would render these materials and thus their fascinating properties accessible in a controlled way. Inspired by a recently reported synthesis of armchair graphene sheets that relied on a benzannulation and Scholl oxidation of a poly(p‐phenylene ethynylene), the same strategy is applied on a cyclic substrate with a short, but well defined CNT as target structure. Herein we report the synthesis of a derivatized [12]cycloparaphenylene acetylene ([12]CPPA) that was accessible employing a Sonogashira macrocyclization. The obtained macrocycle is the largest [n]CPPA reported to date and displays bright turquoise fluorescence with a large quantum yield of 77 %. The [12]CPPA can be transformed by a 12‐fold benzannulation that converts each alkyne to a naphthalene and therefore allows formation of an armchair [12,12]CNT precursor. The final 72‐fold Scholl oxidation to the [12,12]CNT turned out to be challenging and its optimization requires an improved synthetic strategy to produce large quantities of the final precursor. The developed approach poses a potential break through strategy for the production of CNTs and certainly incentivizes synthetic chemists to apply the same methodology for various conjugated macrocycles. [ABSTRACT FROM AUTHOR]

We report on the insertion of electron deficient alkyne, dimethyl acetylene dicarboxylate (DMAD), into the E–Si bond of hypersilyl tetrylenes, PhC(NtBu)2ESi(SiMe3)3 (E = Ge and Sn), at room temperature. Uniquely, the germylene leads to cis alkenes, while the stannylene gives access to trans alkenes, and the insight into divergent stereoselectivity has been obtained by DFT studies. [ABSTRACT FROM AUTHOR]

Organic substances in which the-OH group is directly attached to the carbon atom are called alcohols. Unsaturated alcohols are obtained by replacing the hydrogen of ethylene or acetylene-type compounds with a hydroxyl group. Allyl alcohol, the first representative of the class of unsaturated alcohols, contains oxygen. Allyl alcohol is used in optical resins, protective glasses, paints and coatings and polymer cross-linking agents, as well as in the production of pharmaceuticals, organic chemicals, plastics, herbicides, and pesticides. In organic chemistry, alcohols can be oxidized to aldehydes, ketones, carboxylic acids, and esters that carry a higher oxidation state of carbon. Therefore, the selective oxidation of alcohols is an important issue. The properties and selective oxidation reaction of allyl alcohol were investigated in the presented work. [ABSTRACT FROM AUTHOR]

[Display omitted] The Gibbs free energies of the formation of several polyynes (C 6 H 2 , C 10 H 2 and C 16 H 2) and aromatic species (C 6 H 6 , C 10 H 8 and C 16 H 10) from methane and acetylene at temperatures of 1000–2600 K and atmospheric pressure were obtained by quantum chemical calculations using the RI-MP2 method in the ORCA open source software. At lower temperatures, aromatic species form more readily than polyynes, while at temperatures >2200 K the trend reverses and polyyne formation becomes predominant. [ABSTRACT FROM AUTHOR]

The selective hydrogenation of acetylene is of industrially indispensable in the production of polymer-grade ethylene. The design of non-precious metal catalysts with outstanding performance is of pivotal importance in order to replace the supported Pd–Ag catalysts. Our previous work showed that a copper carbide (CuxC)-containing catalyst exhibited high hydrogenation activity and selectivity under mild conditions. In the present work, Mg(OH)2 was used to modify the CuxC-containing catalyst in order to improve its catalytic performance. Mg(OH)2-modified CuxC-containing catalyst was prepared from a coprecipitate of Cu(OH)2 and Mg(OH)2, which was obtained by precipitation of Cu(NO3)2 and Mg(NO3)2 solution with dropwise addition of NaOH solution, by thermal treatment in C2H2/Ar (0.5%) at 120 ℃ followed by H2 reduction at 150 ℃. The introduction of Mg(OH)2 led to reduced CuxC crystalline size and to increased amount of CuxC crystallites. In addition, the basic nature of Mg(OH)2 is favorable to suppress the undesired oligomerization. The prepared catalyst showed excellent catalytic performance with complete acetylene conversion, low selectivity to unwanted ethane (24%), and high stability at 100 °C and atmospheric pressure in the presence of large excess ethylene in 100 h. [ABSTRACT FROM AUTHOR]

A series of 1-carbonyl-1H-indoles were prepared by 2-iodoanilines and calcium carbide in a one-pot reaction catalyzed by recyclable10% Pb/C, resulting in the corresponding substituted indoles in good yields. This protocol offers several advantages, including the utilization of sustainable, low-cost calcium carbide, an easy-to-handle acetylene source, and recyclable Pb/C catalysts. The synthesis of a series of 1-carbonyl-1H-indoles were prepared by 2-iodoanilines and calcium carbide in a one-pot reaction catalyzed by 10% Pb/C, resulting in the corresponding substituted indoles in good yields. This protocol offers several advantages, including the utilization of sustainable, low-cost feedstock, an easy-to-handle acetylene source, and recyclable Pb/C catalysts. [ABSTRACT FROM AUTHOR]

The main patterns of oxidative chlorination (oxychlorination) with such unsaturated hydrocarbons as propylene, acetylene, 1,3-butadiene, and benzene are considered. It is shown that when the processes are conducted in the gas phase, having heterogeneous copper or palladium based catalysts in the system is preferable. It is shown that palladium in a catalyst promotes processes of substitutive oxychlorination. Stagewise schemes of reactions are given for processes of propylene, acetylene, and benzene oxychlorination along with corresponding kinetic equations. Applied aspects of the above processes are discussed. [ABSTRACT FROM AUTHOR]

This study aimed to reduce smoke and NOx emissions in a diesel engine fuelled with a 20% blend of Calophyllum inophyllum and Prosopis juliflora biodiesel (B20) with neat diesel, supplemented with acetylene at flow rates of 1, 2, and 3 liters per minute (lpm) in dual-fuel mode. Using the Grey-Taguchi method and an L9 (3^3) orthogonal array, the effects of compression ratio, fuel type, and acetylene flow rate were examined. Regression models were developed to predict brake thermal efficiency, smoke, and NOx emissions based on these controllable factors. The study found that the optimal individual values for NOx, brake thermal efficiency, and smoke were 2353 ppm, 31.52%, and 48.7 ppm, respectively. The best-combined results were achieved with a compression ratio of 17.5 and an acetylene flow rate of 3 lpm using the CI20 blend. The findings demonstrated significant improvements in output response factors when the optimal combination was applied, as validated by experimental and artificial neural network (ANN) simulations. The Grey-Taguchi approach proved effective in reducing emissions while enhancing engine performance. [ABSTRACT FROM AUTHOR]

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The rising costs of petroleum-based fuels for internal combustion engines and their detrimental environmental impacts have spurred the search for alternative fuels. This study explores minor modifications to a compression ignition engine, enabling it to operate in dual fuel mode using biofuels as a viable alternative to neat diesel. A novel biofuel was developed using cedar wood oil, and its performance was experimentally investigated in a single-cylinder diesel engine operating at a constant speed. Acetylene was continuously introduced to the engine at a flow rate of 6 L per minute, chosen for its optimal performance, yielding a brake thermal efficiency of over 30.7%. The engine was operated under constant conditions, including a compression ratio of 18, an ignition timing of 23°CA before top dead centre, and an injection pressure of 220 bar. Comparative evaluations were performed by analyzing the combustion characteristics and emission levels of diesel and cedar wood oil-based fuels with and without nanoadditive for diesel, B50 and B100 with a constant acetylene gas supply at 6 Lit/min. The primary objective was to reduce toxic emissions, including smoke, carbon monoxide, hydrocarbons, and nitrogen oxides, released during fuel combustion with the help nanoadditives in fuel. The effects of cerium nanoparticles as an additive were considered in this study due its thermal stability and activation energy which reduce CO and HC emission significantly.The smoke, CO and HC were decreased for B100 + 6L A + 50 ppm blend by 20.21%, 65.52% and 51.42% for 100% load. It is found that cedar wood oil oil with nanoparticle additives could effectively reduce smoke and hydrocarbon emissions while maintaining comparable efficiency to neat diesel and pure biodiesel modes. [ABSTRACT FROM AUTHOR]

We used the chemical vapor deposition process to deposit carbon film at a high temperature (900 °C). The carbon films were deposited on AISI 1006 foils using an acetylene gas. We analyzed the carbon film deposited on the surface using Raman spectroscopy, scanning electron microscopy, and high-resolution transmission electron microscopy to define changes in the bonding structure of the carbon film. The results of Raman spectroscopy and high-resolution transmission electron microscopy revealed that as the acetylene flow rate increased, the shape of the deposited carbon film changed from graphene to graphite. In addition, in order to compare the quality of the carbon film in terms of mechanical and electrical properties, carbon films treated under various conditions were closely analyzed using nano-indenter and a sheet resistance meter. Therefore, the optimal condition (1 Torr-50 sccm) was selected in which graphene was uniformly deposited and had the lowest electrical resistance (500 Ω/sq) and highest hardness (12 GPa). [ABSTRACT FROM AUTHOR]

The mechanism of 1‐azadienes formation from aldimines and arylacetylenes in the KOtBu/DMSO superbasic medium has been explored theoretically using a DFT approach [B2PLYP(D2)/6‐311+G(d,p)//B3LYP/6‐31+G(d)] and a sophisticated model taking the potassium tert‐butoxide and the nearest solvation shell of the potassium cation explicitly into account. The main focus is placed on (i) a detailed analysis of the kinetic and thermodynamic characteristics of the isomerization of intermediate propargylamine into 1‐azadienes, and (ii) the factors determining the isomeric composition of 1‐azadienes with different substituents in the starting arylaldimines and arylacetylenes. Our findings clearly indicate that the mild experimental conditions of 1‐azadienes formation are accounted for by the relatively small activation barrier (ΔG≠≤16.2 kcal/mol) of the limiting step (ethynylation of aldimine with arylacetylenes). The rapid isomerization of propargylamine to 1‐azadiene is found to be due to low activation barriers (ΔG≠≤9.1 kcal/mol) related to the protons transfer. The isomeric composition in the case of various substituted 1‐azadienes is determined solely by the difference in the thermodynamic stability of the 1E,2E‐ and 1Z,2E‐forms. [ABSTRACT FROM AUTHOR]

The scientific and technical bases for ensuring fire and explosion safety in the handling of acetylene are considered. Safe operation with acetylene in the equipment can be ensured by localization of the combustion source by the following methods: phlegmatization of the medium; installation of protective devices, the main of which are fire barriers (their action is based on the phenomenon of flame extinguishing in narrow channels); choice of conditions for combustible gas transportation. To prevent explosion in case of emergency acetylene expiration and to extinguish the flame in closed volumes, the minimum concentration of carbon dioxide is 57% (vol.), nitrogen 70% (vol.). With the help of the Pecle criterion, the values of the critical flame extinguishing diameter for the investigated combustible mixture can be estimated and established. According to safety conditions, acetylene transportation should be carried out at low initial pressures, in pipelines of small diameter and with low hydraulic resistance of fire barrier nozzle.

A pulse-shaping technique in the mid-infrared spectral range based on pulses with a super-Gaussian temporal profile is considered for laser control. We show a realistic and efficient path to the population of a dark rovibrational state in acetylene (C2H2). The laser-induced dynamics in C2H2 are simulated using fully experimental structural parameters. Indeed, the rotation–vibration energy structure, including anharmonicities, is defined by the global spectroscopic Hamiltonian for the ground electronic state of C2H2 built from the extensive high-resolution spectroscopy studies on the molecule, transition dipole moments from intensities, and the effects of the (inelastic) collisions that are parameterized from line broadenings using the relaxation matrix [A. Aerts, J. Vander Auwera, and N. Vaeck, J. Chem. Phys. 154, 144308 (2021)]. The approach, based on an effective Hamiltonian, outperforms today's ab initio computations both in terms of accuracy and computational cost for this class of molecules. With such accuracy, the Hamiltonian permits studying the inner mechanism of theoretical pulse shaping [A. Aerts et al., J. Chem. Phys. 156, 084302 (2022)] for laser quantum control. Here, the generated control pulse presents a number of interferences that take advantage of the control mechanism to populate the dark state. An experimental setup is proposed for in-laboratory investigation. [ABSTRACT FROM AUTHOR]

Infrared (IR) spectroscopy using ultracold helium nanodroplet matrices has proven to be a powerful method to interrogate encapsulated ions, molecules, and clusters. Due to the helium droplets' high ionization potential, optical transparency, and ability to pick up dopant molecules, the droplets offer a unique modality to probe transient chemical species produced via photo- or electron impact ionization. In this work, helium droplets were doped with acetylene molecules and ionized via electron impact. Ion-molecule reactions within the droplet volume yield larger carbo-cations that were studied via IR laser spectroscopy. This work is focused on cations containing four carbon atoms. The spectra of C4H2+, C4H3+, and C4H5+ are dominated by diacetylene, vinylacetylene, and methylcyclopropene cations, respectively, which are the lowest energy isomers. On the other hand, the spectrum of C4H4+ ions hints at the presence of several co-existing isomers, the identity of which remains to be elucidated. [ABSTRACT FROM AUTHOR]

In this report, we have established a Ru(η6-C6 H6)Cl2 catalysed ortho -C–H activation of benzyl thioethers with alkynes under milder reaction conditions. The sulfur atom of benzyl thioethers worked as a directing group for ortho -C–H activation of benzyl thioethers. The reaction was found to tolerate a range of benzyl thioethers as well as alkynes. Moreover, the reaction is significantly influenced by the length of alkyl and aryl thioethers, with the best results being obtained with benzyl thioethers. Kinetic isotopic experiments suggest that the ortho -C–H bond-breaking is not a rate-determining step for the present reaction. In an unusual observation that has not been reported, apart from ortho -C–H activation, under the same reaction conditions, a selective debenzylative hydrothiolation was exclusively obtained with acrylates, which broadens the synthetic impact of benzyl thioethers for the preparation of mixed chalcogen ethers. [ABSTRACT FROM AUTHOR]

Ambient hydrocarbons adsorbed on the contact surface of nanoelectromechanical (NEM) switches would impact its performance. In this study, we utilized reactive molecular dynamics simulations to investigate the cyclic contact/separation process of Pt(111)/C2H2/Pt(111) systems. Our results demonstrate that substrate damage decreases as acetylene coverage increases from sub-monolayer to multilayer. This suppression occurs due to the presence of acetylene molecules, which can suppress direct (Pt–Pt connection) and indirect (Pt–(Cx)–Pt-like connection) interfacial bonding between the two substrates, depending on their coverage. Moreover, we observed the formation of chain-like oligomers after multiple contact/separation simulations in the monolayer model, much more significantly compared with the sub-monolayer and multilayer models. These oligomers arise from polymerization reactions among fragmented acetylene molecules, primarily formed through acetylene dehydrogenation. In the sub-monolayer model, numerous transferred Pt atoms at the interface hinder bonding between acetylene fragments, whereas in the multilayer model, only a few acetylene fragments form during the contact process, due to the well-organized and dense acetylene layer adsorbed on the substrate surfaces. These insights shed light on the atomic-scale mechanisms underlying substrate damage and chain-like oligomers formation in metal NEM switches. [ABSTRACT FROM AUTHOR]

The relative energies of different phases or polymorphs of molecular solids can be small, less than a kilojoule/mol. A reliable description of such energy differences requires high-quality treatment of electron correlations, typically beyond that achievable by routinely applicable density functional theory (DFT) approximations. At the same time, high-level wave function theory is currently too computationally expensive. Methods employing an intermediate level of approximations, such as Møller–Plesset (MP) perturbation theory and the random phase approximation (RPA), are potentially useful. However, their development and application for molecular solids has been impeded by the scarcity of necessary benchmark data for these systems. In this work, we employ the coupled-cluster method with singles, doubles, and perturbative triples to obtain a reference-quality many-body expansion of the binding energy of four crystalline hydrocarbons with a varying π-electron character: ethane, ethene, and cubic and orthorhombic forms of acetylene. The binding energy is resolved into explicit dimer, trimer, and tetramer contributions, which facilitates the analysis of errors in the approximate approaches. With the newly generated benchmark data, we test the accuracy of MP2 and non-self-consistent RPA. We find that both of the methods poorly describe the non-additive many-body interactions in closely packed clusters. Using different DFT input states for RPA leads to similar total binding energies, but the many-body components strongly depend on the choice of the exchange–correlation functional. [ABSTRACT FROM AUTHOR]

Acetylene is produced from the reaction between calcium carbide (CaC2) and water, while the production of CaC2 generates significant amount of carbon dioxide not only because it is an energy-intensive process but also the raw material for CaC2 synthesis is from coal. Here, a comprehensive biomass-to-acetylene process was constructed that integrated several units including biomass pyrolysis, oxygen-thermal CaC2 fabrication and calcium looping. For comparison, a coal-to-acetylene process was also established by using coal as feedstock. The carbon efficiency, energy efficiency and environmental impacts of the bio-based calcium carbide acetylene (BCCA) and coal-based calcium carbide acetylene (CCCA) processes were systematically analyzed. Moreover, the environmental impacts were further evaluated by applying thermal integration at system level and energy substitution in CaC2 furnace. Even though the BCCA process showed lower carbon efficiency and energy efficiency than that of the CCCA process, life cycle assessment demonstrated the BCCA (1.873 kgCO2eq kg-prod−1) a lower carbon footprint process which is 0.366 kgCO2eq kg-prod−1 lower compared to the CCCA process. With sustainable energy (biomass power) substitution in CaC2 furnace, an even lower GWP value of 1.377 kgCO2eq kg-prod−1 can be achieved in BCCA process. This work performed a systematic analysis on integrating biomass into industrial acetylene production, and revealed the positive role of biomass as raw material (carbon) and energy supplier.

It was crucial to develop a catalyst with high catalytic activity at low temperatures, as the zinc‐based catalysts were prone to deactivation in the high‐temperature reaction of acetylene acetoxylation, and Ionic liquid (IL)‐silver (Ag) catalysts were synthesized and applied in acetylene acetoxylation. The X‐ray diffraction, transmission electron microscopy, and X‐ray photoelectron spectroscopy characterizations displayed that Ag species were stabilized in the state of Ag+, and the dispersion of the Ag active species was effectively improved in supported‐ionic‐liquid‐phase (SILP) system. Furthermore, we prepared Ag‐IL liquid phase catalysts for catalyzing acetylene acetoxylation in liquid phase systems. It was demonstrated that the presence of ILs could effectively stabilize the Ag+ active site. The catalytic performance of the Ag‐IL/AC catalyst prepared in this article at a low temperature of 180 °C was 2.5 times that of the traditional Zn/AC catalyst. The development of low‐temperature catalysts would play a driving role in the development of acetylene acetoxylation. [ABSTRACT FROM AUTHOR]

Efficient catalytic methods that allow the use of simple and abundant chemical feedstocks for the preparation of synthetically versatile compounds are central to modern synthetic chemistry. Acetylene is a basic feedstock with a remarkable production over one million tons per year, although it is underutilized in the stereoselective synthesis of fine chemicals. Here we report a facile catalytic multicomponent reaction that allows for the enantio‐ and diastereoselective allylboration of acetylene gas. This process is catalyzed by a chiral copper catalyst, operates without specialized equipment or pressurization, and provides chiral skipped dienes bearing stereodefined and orthogonally functionalized olefins with excellent levels of chemo‐, regio‐, enantio‐ and diastereoselectivity. The combined stereochemical features and orthogonal functionalization make the products privileged structural scaffolds to access the complete set of stereoisomers of the chiral skipped diene core through simple enantio‐ and diastereodivergent pathways. The utility of the method is demonstrated with the enantioselective synthesis of three bioactive natural skipped diene products, namely (+)‐Nyasol, (+)‐Hinokiresinol and Phorbasin C, and other related synthetically relevant chiral molecules. [ABSTRACT FROM AUTHOR]

Synthesis of new polysubstituted furans incorporating reactive phosphorus ylides or N‐acyliminophosphoranes was achieved by the heterocyclization of flexible α‐acyl ketene dithioacetals. This one‐pot tandem reaction was initiated by acyl‐directed desulfurative Sonogashira coupling, followed by 1,6‐addition of phosphine to the in situ‐generated enynone and subsequent 5‐exo‐dig cyclization, as well as phosphoranation. The selectivity toward the two products, i. e. α‐phosphorus ylides vs. α‐N‐acyliminophosphoranes‐substituted furans, was determined by both electron‐deficient acetylenes and copper salts. [ABSTRACT FROM AUTHOR]

The article describes for the first time the synthesis of the diaminoacetylene ligand, which is a by-product of the synthesis of [W(CN)6(bpy)]2− involving the thermal decomposition of (bpyH)3(H3O)[W(CN)8]·H2O. The formation of the diaminoacetylene ligand, H2NC≡CNH2, occurs through protonation of cyanido ligands and the formation of a C–C bond between two neighbouring CN− ligands through a reductive coupling mechanism. In this way, three salts of the anion [W(CN)6(C2N2H4)]2− with cations: PPh4+ (1), rubidium (2), and caesium (3) were isolated and then structurally and spectroscopically characterised. The formation of an additional by-product (PPh4)3[W(CN)8]·4.25H2O (4) was also discussed. IR measurements of the reaction mixture indicate that proton transfer from the Hbpy+ cation is accompanied by the formation of the acetylene ligand. NMR spectra indicate strong interactions between the cyanido ligands and the protons of the acetylene ligand. [ABSTRACT FROM AUTHOR]

Electrocatalytic acetylene hydrogenation to ethylene (E‐AHE) is a promising alternative for thermal‐catalytic process, yet it suffers from low current densities and efficiency. Here, we achieved a 71.2 % Faradaic efficiency (FE) of E‐AHE at a large partial current density of 1.0 A cm−2 using concentrated seawater as an electrolyte, which can be recycled from the brine waste (0.96 M NaCl) of alkaline seawater electrolysis (ASE). Mechanistic studies unveiled that cation of concentrated seawater dynamically prompted unsaturated interfacial water dissociation to provide protons for enhanced E‐AHE. As a result, compared with freshwater, a twofold increase of FE of E‐AHE was achieved on concentrated seawater‐based electrolysis. We also demonstrated an integrated system of ASE and E‐AHE for hydrogen and ethylene production, in which the obtained brine output from ASE was directly fed into E‐AHE process without any further treatment for continuously cyclic operations. This innovative system delivered outstanding FE and selectivity of ethylene surpassed 97.0 % and 97.5 % across wide‐industrial current density range (≤ 0.6 A cm−2), respectively. This work provides a significant advance of electrocatalytic ethylene production coupling with brine refining of seawater electrolysis. [ABSTRACT FROM AUTHOR]

A three-components regioselective synthesis of 3-[2-formamidovinyl(phenyl)amino]-acrylic acid based on an opening of the imidazole ring under the influence of acetylene carboxylic acids esters or cyanophenylacetylene in aqueous acetonitrile in up to 86% yields has been developed. [ABSTRACT FROM AUTHOR]

A selective one-pot method was developed for the synthesis of 2,4-dialkyl-6-(2-methoxyethyl)pyridines in yields of 70–82% by the reaction of terminal acetylenes with 3-methoxypropionitrile in the presence of EtAlCl2, Mg, and Cp2TiCl2 (10 mol.%). [ABSTRACT FROM AUTHOR]

Recently, we suggested liquid and high‐boiling TIPS‐CC‐SF5 (TASP) as a versatile reagent to access so far elusive SF5‐containing building blocks by less specialized laboratories under bench‐top conditions. The synthesis of non‐aromatic SF5 building blocks generally requires on‐site fluorination or pentafluorosulfanylation steps employing toxic and/or gaseous reagents. Herein, we underline the versatility of this reagent by reporting a benign bench‐top protocol for the synthesis of Z‐configured β‐pentafluorosulfanylated vinyl sulfides in good to excellent yields (up to 99 %) with exclusive (Z)‐diasteroselectivity and broad functional group tolerance. This method exploits an in‐situ protodesilylation‐hydrothiolation sequence. This so far uncharted class of compounds was characterized by means of NMR‐spectroscopy as well as SC‐XRD. Furthermore, we suggest the reaction to proceed via a kinetically controlled closed‐shell reaction pathway, corroborated by in‐silico experiments. [ABSTRACT FROM AUTHOR]

It is highly desired that performance of Pd catalysts is improved by the design and preparation of homogeneously dispersed and stablized in many industrial catalytic processes and still a big challenge. Herein, small-sized Pd over Al2O3-flower (f-Al2O3) via compartmentalization strategy is successfully prepared. Ultrafine Pd phases are highly dispersed and thermally stabilized by flower-liked architectures, which not only efficiently suppress Pd aggregation at reaction conditions, but also promote mass transport and reactants access to active sites easily. The catalysts exhibit a stable acetylene conversion of 93% with ethylene selectivity of 94% within a single running of 60 days (60 ℃, GHSV 4500 h−1) without introducing any promoter, and high TOF value (0.4 S−1) are achieved as well. This work provides a facile strategy of improving the activity and thermal stability of Al2O3-supported nano-catalysts in industrial application. [ABSTRACT FROM AUTHOR]

A numerical simulation of the detonation propagation process of acetylene-air under fuel-rich conditions is carried out using a reduced acetylene reaction model. The loose coupling method is used to solve the conservation equations with source terms. The flow is solved explicitly using a gas kinetic scheme, and the chemical reactions are solved implicitly. The numerical results show that the oxidation reaction is the chain initiation in the self-sustained detonation propagation process in rich acetylene. The self-decomposition reaction of acetylene provides the energy to maintain the coupling between the shock wave and the chemical reaction zone. The results show that the initial induced reaction is still an oxidation reaction due to the low activation energy of the oxidation reaction under the condition of low oxygen content. The intensity of the transverse wave is affected by the acetylene concentration. The post-detonation disturbance of temperature is mainly affected by the strength of the tail of transverse wave and the area of the unreacted pocket. With the increase of acetylene concentration, the self-decomposition process of acetylene increases the intensity of the transverse wave tail and improves the degree of temperature homogenization. This creates a formation-fragmentation-regeneration cycle of polycyclic aromatic hydrocarbons. This process changed the branching ratio of polycyclic aromatic hydrocarbons with different structures and delayed the formation of polycyclic aromatic hydrocarbons. When the acetylene concentration is low, the region where the dominant temperature after detonation is 1500 ~ 2500 K provides a favorable environment for the growth of polycyclic aromatic hydrocarbons. [ABSTRACT FROM AUTHOR]

The atomic and electronic structures of two organosilicon polymers [–Ph2Si–(C≡C)2–]n (P1) and [–Ph2Si–(C≡C–C≡C)2–]m (P2) (where Ph is a phenyl group) of acetylene and diacetylene types are studied using the methods of density functional theory and X-ray emission spectroscopy. The SiKβ1 X-ray emission spectra of these polymers are interpreted on the basis of analysis of the distribution of partial electronic states obtained from quantum chemical calculations. The quantitative characteristics of the parameters of the chemical interaction of atoms, such as population, natural charges, and electronic configurations in the studied polymers, are obtained on the basis of analysis of hybrid natural bond orbitals. The values of the polarization coefficients of natural bond orbitals indicate the localization of electron density predominantly on carbon atoms. The electronic configurations for carbon atoms in different fragments differ significantly. For the C atoms of ethynyl (diethynyl) fragments, they are close to the linear σ bond of the sp1.03 (P1) and sp0.95 (P2) type, while for the C atoms of phenyl fragments, they are sp2.42, which are intermediate between sp2 and sp3, in accordance with molecular geometry. The natural charges on Si in both polymers are almost the same: +1.58e, +1.59e (e is the elementary charge), while the natural charges for carbon atoms of the diethynyl group decrease in comparison with the charge for the carbon atom of the ethynyl group from –0.42e to –0.36e. [ABSTRACT FROM AUTHOR]