Search Results (15)

Copper interconnect technology faces limitations due to the electron’s mean free path and electromigration, driving the adoption of cobalt alternatives. This study proposes a novel mechanism to achieve superfilling by tuning the adsorption energy of additive molecules on cobalt surfaces. The adsorption energies of additives are tailored by changing molecular structures with different functional groups. Computational results reveal that carbon–carbon triple bonds critically strengthen adsorption, while ether bonds further enhance binding on distinct cobalt crystallographic planes. Specifically, 1,4-bis(2-hydroxyethoxy)-2-butyne (BEO) containing both triple bonds and ether groups exhibits the highest adsorption energy (−22.62 eV). Replacing ether with hydroxyl groups in 2-butyne-1,4-diol (BOZ) reduces the adsorption energy to −10.39 eV, while eliminating triple bonds in 1,4-butanediol diglycidyl ether (BDE) further decreases it to −8.43 eV. Experimental studies demonstrate that BOZ and BEO preferentially adsorb on the (101) and (110) planes of hexagonal close-packed cobalt (HCP-Co) due to their differential adsorption energies. This selective suppression promotes preferential growth along the densely packed (002) orientation. This leads to a trench-filling process dominated by the most densely packed plane, resulting in better electrical performance. Superfilling is achieved when molecular adsorption energies are in the range of 5–8 eV. The work establishes a functional group design strategy to regulate additive adsorption, enabling crystallographic control for advanced cobalt electrodeposition processes. Full article

Alkynol semi-hydrogenation plays a vital role in industrial processes, due to the significance of its main product, enol, in high-end chemical synthesis, such as medicine, pesticide, food additives, and polymer monomer synthesis. Multiple intermediates are formed through a complex series of parallel or continuous reactions under varying conditions. However, the selectivity and efficiency of catalysts for producing these products still pose significant challenges. This review aims to thoroughly discuss the challenges and advancements in catalysts using different species and supports under various reaction conditions. Furthermore, strategies to enhance the yield and rate of enols are summarized based on noble metals, non-noble metals, and metal comparisons. By addressing diverse catalysts and reaction conditions, this review provides valuable insights into improving the semi-hydrogenation of acetylenic alcohols to enols. Full article

Palladium catalysts were obtained by the adsorption method involving the sequential deposition of polyvinylpyrrolidone (PVP) and then palladium ions on a modified zinc oxide surface without high-temperature calcination and reduction stages. The immobilized PVP-palladium catalysts were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET), infrared spectroscopy (IRS), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and elemental analysis methods. It was found that the introduction of polymer into the catalyst’s composition promotes the dispersion and uniform distribution of active phase nanoparticles (PdO, Pd⁰) on the surface of zinc oxide. The catalysts were tested in the hydrogenation of complex acetylene alcohol, 3,7,11-trimethyldodecyn-1-ol-3 (C₁₅-yn) under mild conditions (0.1 MPa, 40 °C). For comparison, studies on stereoselective hydrogenation of the short-chain alcohol 2-hexynol-1 were performed. It was shown that modification of the catalyst with polymer improves its catalytic properties. High C₁₅-alkenol selectivity (98%), activity (W = 70 × 10⁻⁶ mol/s), and stability (turnover number (TON) 62,000) were achieved on a Pd-PVP/ZnO catalyst. Varying the active phase made it possible to reduce the metal content without deteriorating the catalytic performance of the catalyst. Full article

A new synthetic procedure for obtaining two previously reported donor-acceptor butadiene dyes, namely 5-(3,3-bis(4-methoxyphenyl)allylidene)-1,3-diethyl-2-thioxodihydropyrimidine-4,6(1H,5H)-dione and 5-(3,3-bis(4-(dimethylamino)phenyl)allylidene)-1,3-diethyl-2-thioxodihydropyrimidine-4,6(1H,5H)-dione, based on the InCl₃-catalyzed coupling 1,3-diethyl-2-thiobarbituric acid with 1,1-bis(4-methoxyphenyl)prop-2-yn-1-ol and 1,1-bis(4-(dimethylamino)phenyl)prop-2-yn-1-ol, respectively, is presented. The reactions, which cleanly proceed in water under MW irradiation, involve the initial generation of the corresponding enals by Meyer-Schuster rearrangement of the alkynols and their subsequent Knoevenagel condensation with the 2-thiobarbituric acid derivative. By following the same approach, the novel butadiene 5-(3,3-bi([1,1′-biphenyl]-4-yl)allylidene)-1,3-diethyl-2-thioxodihydropyrimidine-4,6(1H,5H)-dione, which was characterized by ¹H and ¹³C{¹H} NMR, IR, UV-Vis, elemental analysis and HRMS, was synthesized in 79% yield. Full article

This work is addressing the selective hydrogenation of alkynols over hybrid catalysts containing Pd-nanoparticles, within newly synthesized hyper-cross-linked polystyrenes (HPS). Alkynols containing C₅, C₁₀, and C₂₀ with a terminal triple bond, which are structural analogues or direct semi-products of fragrant substances and fat-soluble vitamins, have been studied. Selective hydrogenation was carried out in a batch mode (ambient hydrogen pressure, at 90 °C, in toluene solvent), using hybrid Pd catalysts with low metal content (less than 0.2 wt.%). The microporous and mesoporous HPS were both synthesized and used as supports in order to address the influence of porosity. Synthesized catalysts were shown to be active and selective: in the case of C₅, hydrogenation selectivity to the target product was more than 95%, at close to complete alkynol conversion. Mesoporous catalysts have shown some advantages in hydrogenation of long-chain alkynols. Full article

Efficient methods have been developed for synthesizing previously unknown macrodiolides incorporating 1Z,5Z-diene and 1,3-diyne moieties in 54–84% yields and with >98% stereoselectivity by means of the intermolecular cyclocondesation of (7Z,11Z)-octadeca-7,11-dienedioic acid with α,ω-diols catalyzed by hafnium triflate Hf(OTf)₄ as well as via the oxidative coupling of α,ω-diynes obtained by the esterification of (7Z,11Z)-octadeca-7,11-dienedioic acid with alkynols. The synthesized macrodiolides exhibit cytotoxic activity toward the Jurkat, K562, U937, HL-60, HeLa, and Hek293 cell lines in vitro. Full article

In the development of earlier-initiated studies on the synthesis of natural and synthetic neuritogenic alkynols, lembehynes A–C—which simultaneously exhibit high antitumor activity—we developed a method for the synthesis of an analogue of natural lembehyne B containing a phenyl radical in its structure. It is shown that the synthesized aromatic analogue of lembehyne B exhibits higher antitumor activity in vitro than a number of tumor cell lines (Jurkat, K562 and U937). Full article

An efficient method for the synthesis of a partially deuterated analogue of the natural neuritogenic alkynol, lembehyne B, has been developed for the first time, based on the use of a new reaction of Ti-catalyzed cross-cyclomagnesiation of O-containing 1,2-dienes and terminal aliphatic 1,2-dienes using EtMgBr in high yield. The introduction of two deuterium atoms is carried out at the stage of treatment of the formed in situ magnesacyclopentane with D₂O. Full article

Homogeneous palladium-catalyzed (Pd-catalyzed) cyclocarbonylation of unsaturated allylic alcohols and alkynols in the presence of hydrogen forms lactone products with important applications in the food, perfume, and polymer industry. In this work, the cyclocarbonylation of 2-methyl-3-buten-2-ol was studied for the first time using a very active Pd-DPEphos (bis[(2-diphenylphosphino)phenyl]ether) catalyst in the presence of the ionic liquid (IL) [BMIM]Cl (1-butyl-3-methylimidazolium chloride) in dichloromethane to selectively produce 4,4-dimethyl-γ-butyrolactone. The effect of different parameters such as temperature, gas partial pressures, time of reaction, substrate and ligand concentrations were investigated and found to provide optimal conditions for lactonization (95 °C, 28 bar (CO/H₂/N₂: 20/5/3)), 18 h, 0.1 M substrate, and 16 mol% DPEphos), which were significantly milder than previously reported systems for cyclocarbonylation. Importantly, the study further showed that presence of the IL in the reaction mixture provided stabilization of the catalyst system and prevented formation of Pd-black, which allowed reuse of the catalytic system in consecutive reactions after intermediate extraction of the lactone product. Full article

Alkenols are commercially important chemicals employed in the pharmaceutical and agro-food industries. The conventional production route via liquid phase (batch) alkynol hydrogenation suffers from the requirement for separation/purification unit operations to extract the target product. We have examined, for the first time, the continuous gas phase hydrogenation (P = 1 atm; T = 373 K) of primary (3-butyn-1-ol), secondary (3-butyn-2-ol) and tertiary (2-methyl-3-butyn-2-ol) C₄ alkynols using a 1.2% wt. Pd/Al₂O₃ catalyst. Post-TPR, the catalyst exhibited a narrow distribution of Pd^δ- (based on XPS) nanoparticles in the size range 1-6 nm (mean size = 3 nm from STEM). Hydrogenation of the primary and secondary alkynols was observed to occur in a stepwise fashion (-C≡C- → -C=C- → -C-C-) while alkanol formation via direct -C≡C- → -C-C- bond transformation was in evidence in the conversion of 2-methyl-3-butyn-2-ol. Ketone formation via double bond migration was promoted to a greater extent in the transformation of secondary (vs. primary) alkynol. Hydrogenation rate increased in the order primary < secondary < tertiary. The selectivity and reactivity trends are accounted for in terms of electronic effects. Full article

Semihydrogenation of 2-methyl-3-butyn-2-ol (MBY) was studied in a 5 m tube reactor wall-coated with a 5 wt% Pd/ZnO catalyst. The system allowed for the excellent selectivity towards the intermediate alkene of 97.8 ± 0.2% at an ambient H₂ pressure and a MBY conversion below 90%. The maximum alkene yield reached 94.6% under solvent-free conditions and 96.0% in a 30 vol % MBY aqueous solution. The reactor stability was studied for 80 h on stream with a deactivation rate of only 0.07% per hour. Such a low deactivation rate provides a continuous operation of one month with only a two-fold decrease in catalyst activity and a metal leaching below 1 parts per billion (ppb). The excellent turn-over numbers (TON) of above 10⁵ illustrates a very efficient utilisation of the noble metal inside catalyst-coated tube reactors. When compared to batch operation at 70 °C, the reaction rate in flow reactor can be increased by eight times at a higher reaction temperature, keeping the same product decomposition of about 1% in both cases. Full article

The paper describes a convenient and efficient method for regioselective synthesis of phosphorylated α-hydroxyallenes using an atom economical [2,3]-sigmatropic rearrangement of intermediate propargyl phosphites or phosphinites. These can be readily prepared via reaction of protected alkynols with dimethyl chlorophosphite or chlorodiphenyl phosphine respectively in the presence of a base. Full article

The last decade has witnessed dramatic growth in the number of reactions catalyzed by gold complexes because of their powerful soft Lewis acid nature. In particular, the gold-catalyzed activation of propargylic compounds has progressively emerged in recent years. Some of these gold-catalyzed reactions in alkynes have been optimized and show significant utility in organic synthesis. Thus, apart from significant methodology work, in the meantime gold-catalyzed cyclizations in alkynol derivatives have become an efficient tool in total synthesis. However, there is a lack of specific review articles covering the joined importance of both gold salts and alkynol-based compounds for the synthesis of natural products and derivatives. The aim of this Review is to survey the chemistry of alkynol derivatives under gold-catalyzed cyclization conditions and its utility in total synthesis, concentrating on the advances that have been made in the last decade, and in particular in the last quinquennium. Full article

A natural alkynol group-substituted thiophene, 2-(penta-1,3-diynyl)-5-(3,4-dihydroxybut-1-ynyl)-thiophene (PDDYT), was isolated from the roots of Echinops grijsii Hance. It possessed potent NAD(P)H: quinone oxidoreductase1 (NQO1) inducing activity and could activate Keap1-Nrf2 pathway effectively in murine hepatoma Hepa 1c1c7 cells. Further investigations indicated that the activation of Keap1-Nrf2 pathway by PDDYT might be attributed to the activation of Akt and depleting the cellular glutathione (GSH). Full article