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A mathematical model is proposed for the replacement of methane with carbon dioxide in a hydrate contained in a reservoir in thermodynamic equilibrium with water and free methane. The substitution reaction region is assumed to be narrow enough to be approximated by the conversion front. A self-similar solution is found that reduces the problem to the numerical analysis of a system of transcendental equations. Numerical experiments show that there exist three characteristic regimes of injection, whose implementation depends on the amount of water in the free state in the reservoir. [ABSTRACT FROM AUTHOR]

A conjugated diblock copolymer of poly(3-hexylthiophene)-block-poly(2-(4,6-dichlorotriazin-2-yl]oxy)ethyl methacrylate) (P3HT-b-PDCTMA) has been obtained via the combination of Grignard metathesis method and organo-catalyzed atom transfer radical polymerization with a polymerization conversion of 73%. The synthesized diblock copolymer P3HT-b-PDCTMA exhibited an Mn of 17,500 g/mol, which is approximately close to the theoretical value, and with polydispersity index (Đ) of 1.42. The conjugated diblock copolymer P3HT-b-PDCTMA bears functional reactive triazine chloride groups that act as a platform to react with mercaptan or amine groups via efficient nucleophilic aromatic substitution reactions. The chemical structures and macromolecular characteristic properties of the "rod–coil" conjugated diblock copolymers have been characterized by FT-IR, 1H NMR spectroscopy and gel permeation chromatography. In addition, their optical properties and conformation have been investigated via UV–Vis spectroscopy. [ABSTRACT FROM AUTHOR]

Intercalation of noble metals into non-van der Waals solids provides a new avenue to synthesize novel nanolaminated compounds with distinct material properties. Herein, we use solid-state reaction at 400 °C to prepare Cr2AuC from two Cr-based Mn+1AXn phase precursors and demonstrate the formation of Cr2AuC upon full replacement of Ga layers with Au in Cr2GaC thin films via thermal substitution reaction. The resulting Cr2AuC exhibits 2.7% lattice expansion relative to the original Cr2GaC, whereas Ge in a Cr2GeC thin film was sparsely replaced by Au, as revealed by electron microscopy and x-ray diffraction analysis. To explain the observed differences, using ab initio calculations, we consider the bonding properties of Cr2GaC and Cr2GeC, and the energetic driving forces for substitution by evaluating the mixing free energy of Au on both A-sites of the MAX phases, and of both A-elements in the surrounding Au lattice. The results suggest that it is somewhat easier to mix Au on the A-site in Cr2GaC than in Cr2GeC, and substantially easier to mix Ga into the Au-lattice than Ge. Finally, we discuss how the gained insights can be consulted for exploring a wider class of Mn+1AXn phases with intercalated noble metals.

Herein we present an efficient method to synthesize novel complex ureas from simple ureas, with potential pharmacological activity. First, 3‐methylindole ketones are protected via a two‐phase N‐tosylation reaction catalyzed by NBu4HSO4 as the PTC. Second, an NBS bromination of the terminal methyl group is performed with high selectivity and very good yields. Finally, complex novel and promising ureas are synthesized in 46 %–92 % yields using non‐base‐catalyzed substitution reactions with simple monosubstituted and disubstituted ureas. All products were easily purified through column chromatography and/or crystallization. The overall procedure produces very high yields and selectivity for bromination. [ABSTRACT FROM AUTHOR]

Deamination of 1-aminoalkylphosphonic acids in the reaction with HNO2 (generated "in situ" from NaNO2) yields a mixture of substitution products (1-hydroxyalkylphosphonic acids), elimination products (vinylphosphonic acid derivatives), rearrangement and substitution products (2-hydroxylkylphosphonic acids) as well as H3PO4. The variety of formed reaction products suggests that 1-phosphonoalkylium ions may be intermediates in such deamination reactions. [ABSTRACT FROM AUTHOR]

The substitution reaction of phosphinates with a binaphthyloxy group at the phosphorus atom with lithium alkoxides proceeded with good to high efficiencies to give P‐chirogenic phosphinates with a high enantiomeric ratio. As alcohols, primary, secondary, and tertiary alcohols could be used, and the use of tert‐butyl alcohol yielded the products with a higher enantiomeric ratio. A substrate with two different alkyl groups on the phosphorus atom could also participate in the substitution reaction to give the corresponding products in good yields with excellent selectivity. The molecular structures of one of the substrates and the corresponding products, determined by X‐ray analyses, proved that the substitution reaction at the phosphorus atom proceeded with inversion of the absolute configuration. The usefulness of the reaction was demonstrated by using it to prepare a drug candidate for Duchenne muscular dystrophy. Finally, thionation of the resulting phosphinates was carried out to form P‐chirogenic phosphinothioates. [ABSTRACT FROM AUTHOR]

Abstract The substitution reaction of phosphinates with a binaphthyloxy group at the phosphorus atom with lithium alkoxides proceeded with good to high efficiencies to give P‐chirogenic phosphinates with a high enantiomeric ratio. As alcohols, primary, secondary, and tertiary alcohols could be used, and the use of tert‐butyl alcohol yielded the products with a higher enantiomeric ratio. A substrate with two different alkyl groups on the phosphorus atom could also participate in the substitution reaction to give the corresponding products in good yields with excellent selectivity. The molecular structures of one of the substrates and the corresponding products, determined by X‐ray analyses, proved that the substitution reaction at the phosphorus atom proceeded with inversion of the absolute configuration. The usefulness of the reaction was demonstrated by using it to prepare a drug candidate for Duchenne muscular dystrophy. Finally, thionation of the resulting phosphinates was carried out to form P‐chirogenic phosphinothioates.

Copyright of Journal of Education & Science is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Defect states in perovskite films restrict the interfacial stability and open-circuit voltage of perovskite solar cells. Here, aiming at superior interfacial passivation, we investigate the reconfiguration of perovskite interface by the interaction between a series of quaternary ammonium bromides (QAB) and lead—halide (Pb—X) octahedrons. Bromide—iodide substitution reaction or R4NBr addition reaction may occur on the perovskite surface, which is related to the steric hindrance of quaternary ammonium cations. On this basis, the perovskite surface morphology, band structure, growth orientation and defect states are reconstructed via the R4NBr addition reaction. This ordered lead—halide adduct could effectively repair the imperfect perovskite/hole transportation layer interface to suppress non-radiative recombination and ion migration toward ultralong carrier lifetime surpassing 10 µs. The resulting perovskite solar cells yield the efficiency of 23.89% with steady-state efficiency of 23.70%. The passivated cells can sustain 86% of initial efficiency after 200-h operation, which is attributed to the passivation effect and hydrophobic characteristics. This work provides an avenue for reconfiguring perovskite surface by QABs. [ABSTRACT FROM AUTHOR]

The paper presents the results of an experimental investigation of the morphology of copper and silver thin films synthesized by the substitution reaction method. Silver films were synthesized by immersing polished substrates of copper (M1 brand) into silver nitrate solution. Copper films were synthesized by immersing substrates of iron (electrolytic iron brand) and also of iron with vacuum deposited tin film of 5 μm thick into copper vitriol solution. The morphology of synthesized films was analyzed by a scanning electron microscope. The research has shown that the metal films with the thickness of around 1 μm are formed 2 seconds after the reaction start point. The films consist of crystal micro- and nanodendrites. The silver films also contain crystalline plates of silver oxide with characteristic size up to 2 μm. With an increase of reaction time the metal layers are compacted. And minimal pore sizes in this case are 20 nm. The synthesized films can be used for the creation of semiconductor-metal micro- and nanostructures for photocatalytic water splitting. Such films can be also applied in chemical sensors and biosensors for surface enhancement of Raman scattering.

The reactions of silver nitrate with triphenyl-, tri(para-tolyl)-, and tris(2-methoxy-5-bromophenyl)stibine in polar solvents afford complexes [(Ph3Sb)3AgNO3], [(p-Tol3Sb)4Ag][NO3] (I), and [(2-MeО-5-Br-C6H3)3SbAg(μ2-NO3)(Ме3CN)]2·2[(2-MeО-5-Br-C6H3)3SbAgNO3(Ме3CN)] (II). Complex [(Ph3Sb)3-AgNO3] reacts with chloroacetic and ferrocenecarboxylic acids in the presence of triethylamine to form the corresponding carboxylates [(Ph3Sb)3AgOC(O)CH2Cl] (III) and [(Ph3Sb)3AgOC(O)C5H4FeC5H5] (V). Solvate [(Ph3Sb)3AgOC(O)CH2Cl] (IV)·1/2С4Н8О2 is formed after the recrystallization of complex III from dioxane. The silver and antimony atoms in all complexes are found by X-ray diffraction to be tetracoordinate (CIF files CCDC nos. 1985086, 2019358, 1984428, 1992301, and 1973285 for compounds I–V, respectively). [ABSTRACT FROM AUTHOR]

The elusive monosubstituted diruthenium complexes [Ru2Cl(DAniF)(O2CMe)3] (1), [Ru2Cl(DPhF)(O2CMe)3] (2), [Ru2Cl(D-p-CNPhF)(O2CMe)3] (3), [Ru2Cl(D-o-TolF)(O2CMe)3] (4), [Ru2Cl(D-m-TolF)(O2CMe)3] (5), [Ru2Cl(D-p-TolF)(O2CMe)3] (6) and [Ru2Cl(p-TolA)(O2CMe)3] (7) have been synthesized using for the first time ultrasound-assisted synthesis to carry out a substitution reaction in metal–metal bonded dinuclear compounds (DAniF− = N,N′-bis(4-anisyl)formamidinate; DPhF− = N,N′-diphenylformamidinate; D-p-CNPhF− = N,N′-bis(4-cyanophenyl)formamidinate; D-o/m/p-TolF− = N,N′-bis(2/3/4-tolyl)formamidinate; p-TolA− = N-4-tolylamidate). This is a simpler and greener method than the tedious procedures described in the literature, and it has permitted to obtain water-soluble complexes with good yields in a short period of time. A synthetic study has been implemented to find the best experimental conditions to prepare compounds 1–7. Two different types of ligands, formamidinate and amidate, have been used to check the generality of the method for the preparation of monosubstituted complexes. Five new compounds (2–6) have been obtained using a formamidinate ligand, the synthesis of the previously described compound 1 has been improved, and an unprecedented monoamidate complex has been achieved (7). The crystal structures of compounds 3 and 7 have been solved by single crystal X-ray diffraction. These compounds show the typical paddlewheel structure with three acetate ligands and one formamidinate (3) or amidate (7) bridging ligand at the equatorial positions. The axial positions are occupied by the chloride ligand giving rise to one-dimensional polymer structures that were previously unknown for monosubstituted compounds.

Deamination of 1-aminoalkylphosphonic acids in the reaction with HNO2 (generated “in situ” from NaNO2) yields a mixture of substitution products (1-hydroxyalkylphosphonic acids), elimination products (vinylphosphonic acid derivatives), rearrangement and substitution products (2-hydroxylkylphosphonic acids) as well as H3PO4. The variety of formed reaction products suggests that 1-phosphonoalkylium ions may be intermediates in such deamination reactions.

A promising method was proposed for the sulfonation of polyphenylquinoxaline films with sulfuric acid. The sulfonation in the films was confirmed by X-ray photoelectron and IR spectroscopies. The thermal characteristics and dielectric properties of the sulfonated films were studied. [ABSTRACT FROM AUTHOR]

The chemical conversion of the surface termination of 2D transition metal carbides/nitrides (MXenes) has opened up a design space that previously had not been extensively explored for this functional material. Herein, via a simple sealed thermal method, the amino terminated groups were successfully introduced on Ti 3 C 2 MXene surface. The substitution reaction of amino group to hydroxyl group was proposed to elucidate this aminated process. As the amination would reduce the carrier density on the surface of MXene, the electrical conductivity of MXene-NH 2 film decreased, while it still reached a high conductivity of 2.11 × 104 S m−1. This film also possessed an excellent electromagnetic interference shielding effectiveness of 16160 dB cm2 g−1. Importantly, although the introduction of amino termination altered Zeta potential value, Zeta potential sign remained negative and the MXene-NH 2 exhibited excellent dispersity in water similar to that of traditional MXenes. Furthermore, the existence of covalent bonds endowed MXene-NH 2 polymer composite film with improved mechanical properties. Compared with that of traditional CMC/MXene film, the tensile strength and fracture energy of CMC/MXene-NH 2 increased by 65.5% and 132.7%, respectively. These results demonstrated that the introduction of amino terminated group on MXene surface would be an effective strategy to obtain higher performance MXene-based films. [Display omitted] [ABSTRACT FROM AUTHOR]

In the present article, utilizing the mPW1PW91 functional, quantum chemical computations were applied to find the impact of indenyl on the ligand substitution reaction in the (η5‐C9H7)Co(CO)2 complex. The solvent impacts were surveyed utilizing the self‐consistent reaction field theory based on the conductor‐like polarizable continuum model. Six aprotic and protic solvents were selected. Co–C and Co–P bond distances changes in the reactant and product complexes were illustrated. The thermodynamic parameters of carbonyl ligand substitution reactions in the (η5‐C5H5)Co(CO)2 and (η5‐C9H7)Co(CO)2 complexes were calculated in the gas and solution phases. Also, rate constant values of these reactions were calculated within 300−1200 K utilizing transition state theory based on the statistical thermodynamics in the gas phase. The computed relative rate constant values (kr) indicated good compatibility with the experimental value in a similar reaction. [ABSTRACT FROM AUTHOR]

Copyright of Polimery is the property of Industrial Chemistry Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The reactions of pentaphenylantimony with 2,4-difluoro-, 2,5-difluoro-, and 2-chloro-4-fluorophenol in a benzene–octane mixture of solvents afford tetraphenylantimony aroxides Ph4SbOC6H3F2-2,4 (I), Ph4SbOC6H3F2-2,5 (II), and Ph4SbOC6H3(Cl-2)(F-4) (III). According to the X-ray diffraction analysis data (CIF files CCDC nos. 1973286 (I), 1975709 (II), and 1973305 (III)), the antimony atoms in the compounds have the coordination of a distorted trigonal bipyramid with the aroxide oxygen atom in the axial position. The OSbС axial angles in compounds I–III are 177.86(6)°, 177.29(7)°, and 174.34(6)°, respectively. The geometric parameters of the molecules in compounds I–III are similar in the Sb−Ceq and Sb−O bond lengths (2.118(2)−2.127(2) and 2.1780(16) Å in I; 2.122(2)−2.130(2) and 2.179(2) Å in II; and 2.116(2)−2.119(2) and 2.1803(16) Å in III). The structural organization in crystals of the compounds is due to weak hydrogen bonds involving F atoms and C–H∙∙∙π interactions. These interactions result in the organization of the molecules in the crystal of compound I into a three-dimensional network, paired chains are formed in compound II, and the molecules of compound III are organized into layers. [ABSTRACT FROM AUTHOR]

In recent years, C–C, C–N, and C–O bonds constructed by C–H functionalization have reached considerable attention due to excellent functional group tolerance, cost‐effectiveness, and atom‐economy. Biaryl compounds are one of the important skeletons in the field of organic chemistry, and have been extensively applied to pharmaceuticals, functional materials, and agrochemicals. However, there have been far fewer reports on C–H functionalization by employing biaryls as substrates. Herein we comprehensively review the C–H functionalization of biaryls including annulation/substitution reactions. The discussion is subdivided according to specific reaction types. In summary, we analyzed the corresponding reaction from the points of view of conditions, directing groups, mechanism, and applications. We hope that this minireview will be beneficial for more synthetic chemists to grasp the design of C–H functionalization of biaryl compounds and enlighten them with more ideas on this issue. [ABSTRACT FROM AUTHOR]

Purpose: Chromium species in higher oxidation states are toxic and carcinogenic. But lower oxidation state as Cr(III) microelement shows potential antimicrobial properties. Cefoperazone sodium is a parenteral bactericidal third-generation cephalosporin antibiotic effective in treating Pseudomonas bacterial infections. A new drug formed with the complexation of metal and drug. Hence, newer coordinated drugs were explored that can also show the antimicrobial effectiveness similar to free drug. Methods: cis-[Cr(C2O4)2(H2O)2]− was synthesized by the proposed method and its complexation with cefoperazone was done by reflux for 5–6 h with stirring. The structure was characterized by spectroscopic techniques (UV, IR, mass, and AAS). The antimicrobial study was done using agar disk-diffusion method. The interaction of the ligand substitution reaction between cis-[Cr(C2O4)2(H2O)2]− and cefoperazone (CFZ) has been investigated in aqueous medium. The reaction has been found to proceed by depending on ligand concentration. Results: The kinetic reaction was studied at [CFZ] varied from 1.50 × 10−2 mol dm−3 to 4.50 × 10−2 mol dm−3 with pH variation from 3.0 to 5.0. The rate of reaction is found to increase in [H+] and [CFZ]. The activation parameters ΔH# and ΔS# are found to be 42.72 kJ mol−1 and − 182.41 J K−1 mol−1 respectively. The positive values of activation enthalpy (ΔH#) shows that the decomposition process is endothermic. Conclusion: Compared to the free cefoperazone, complexation with chromium(III) metal ion shows similar antimicrobial activity. The reaction takes place through an associative interchange mechanism. [ABSTRACT FROM AUTHOR]

In this paper, a synthetic route of oral antidiabetic drug-linagliptin based on the removal of protective group was studied. The key intermediate was obtained from methyl urea by 6 steps of cyclization, nitrosation, reduction, cyclization, Bromination and substitution. The intermediate 2-chloromethyl-4-methylouwarin was synthesized from o-aminoacetophenone by condensation, cyclization and reduction. Based on these two intermediates, linagliptin was prepared by a series of substitution reactions. The experimental results show that the synthesis efficiency of this method is high. In addition, the raw material of the synthesis method is cheap and easy to obtain, the reaction conditions are mild, and the post-treatment is simple, which lays a foundation for industrial production. [ABSTRACT FROM AUTHOR]

The property of lower soda and alumina contents of iron hydrogarnet can reduce the loss of soda and alumina in Bayer and Sub-molten salt process. Thus, the economic efficiency of alumina production could be improved. How to solve the effective formation of iron hydrogarnet in concentrated caustic aluminate solution and its cycle in the digestion process has become an important research topic. The base of hydroferrire desilication agents (calcium hydroferrite CHF, calcium hydroferrocarbonate CHFC, calcium hydroferrosulfate CHFS) were synthesized, the desilication experiments and desilication products (DSPs) were characterized, the results show that the hydroandradite and aluminum-hydroandradite are the main components in DSPs. The free energy of synthesis reaction of desilication agents and desilication reaction in concentrated caustic solution was investigated using the complex silicate theory. The investigation shows that CHFC has the better desilication performance for hydroferrite desilication agents. The free energy of desilication reaction in concentrated caustic solution using hydroandradite is affected by the initial silica coefficient, the reacted silica coefficient of DSPs, and the reaction temperature. From the point of view of thermodynamics, the substitution reaction between aluminum to iron that occurred in the concentrated caustic aluminosilicate solution main occurs when the higher initial silica coefficient of hydroandradite and the higher alumina coefficient of reaction product. • The hydroandradite and aluminum-hydroandradite is the main compositions in DSPs in desilication reaction using hydroferrite agents • That CHFC has the better desilication performance in the thermodynamic point • The free energy of desilication reaction using hydroandradite is affected by the initial silica coefficient, that of DSPs and temperature • The substitution reaction between aluminum to iron mainly occurs when the higher initial silica coefficient and alumina coefficient of product [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The substitution reactions of dinuclear complex with sulfur-containing species. • The substituted complexes were verified by some spectroscopies and X-ray diffraction. • The linkage isomerism of a dmso ligand on the dinuclear complex was revealed. Abstract The substitution reactions of a NO-ligated dinuclear ruthenium complex with ammonium thiocyanate (NH 4 SCN), sulfur, and dimethyl sulfoxide (DMSO) gave the corresponding mononitrosyl dinuclear complexes, except for reaction with sulfur, where diastereomers of a S 2 -bridged tetranuclear complex along with a NO- and S 2 -bridged dinuclear complex were obtained. According to the scan rate dependent cyclic voltammograms, linkage isomerism of a dmso ligand on the dinuclear complex was revealed, and the linkage isomer was obtained from the chemical oxidation. [ABSTRACT FROM AUTHOR]

Abstract Stereochemistry of direct conversion of polyamides to hydroxyesters was investigated using model compounds. Optically active secondary-alkyl amines underwent the conversion to corresponding secondary alcohols in moderate yields by treatment with supercritical methanol in the presence of glycolic acid. The reaction progressed through almost completely stereochemical inversion to give secondary alcohols in high yields. Thus, the substitution reaction of the amino group to hydroxyl group progresses through S N 2 type transition state accompanying with stereoinversion. Highlights • Primary and secondary alkyl amines were used as model compounds to investigate depolymerization mechanism of polyamides. • The reaction pathway depends on the alkyl group and primary alkyl amine prefers substitution process to elimination process. • Chiral secondary alkyl amines undergo complete stereoinversion, indicating the substitution goes through SN2 mechanism. [ABSTRACT FROM AUTHOR]

Hypothesis It is still difficult to prepare hydrophilic fluorinated graphene with abundant oxygen functional groups and high F/C ratio. Experiments Herein, selective fluorination for graphene oxide (GO) was realized to prepare highly oxygen/fluorine dual functionalized graphene (OFG) under a mild temperature without damaging the sheet structure. Its O/C and F/C ratios came up to 0.58 and 0.19 respectively, which contained the intactly reserved oxygen functional groups from GO during fluorination and C-F bonds from addition reaction between aromatic region and F 2 , as demonstrated via X-ray photoelectron spectroscopy (XPS), thermo gravimetric analysis (TGA), Raman measurements and so on. Findings Experiments and density functional theory (DFT) calculations revealed that oxygen functional groups in-situ promoted addition reaction between aromatic region and F 2 , and the critical point was confirmed that oxygen functional groups began to react with F 2 by substitution reaction. As-prepared OFG presented a 47% and 31% decrease of wear rate compared with that of pure water and GO, respectively. During friction process, the abundant oxygen functional groups of OFG contributed to hydrophilic property and introduced fluorine played an important role in enhancing the tribological performance by self-lubricating behavior. Such mild and simple method is achieved to expand the application of fluorinated graphene in aqueous environment. [ABSTRACT FROM AUTHOR]

Quantum chemical calculations have been performed for the substitution reactions of the aluminum chlorogermylenoid H2GeClAlCl2 with HF, H2O, NH3, HCl, H2S, and PH3 to get more insights into the reactivity of H2GeClAlCl2. The theoretical calculated results indicated that the substitution reactions of H2GeClAlCl2 with HF, H2O, NH3, HCl, H2S, and PH3 proceeded in a concerted manner. There were one transition state and one intermediate which connected the reactants and the products along the potential energy surface. The six substitution reactions of H2GeClAlCl2 with HF, H2O, NH3, HCl, H2S, and PH3 are compared with the addition reaction s of H2Ge with these hydrides. And based on the calculated results we concluded that the substitution reactions of H2GeClAlCl2 with these hydrides involve two steps, one is dissociation onto H2Ge with AlCl3, and the other is the addition reactions of H2Ge with HF, H2O, NH3, HCl, H2S, and PH3.

Functional adamantane derivatives are interesting as active pharmaceutical ingredients, building blocks for supramolecular ensembles, and ligands in light of the coordination chemistry of functional materials. In this communication, synthesis of two isomeric 1,3-bis(1,2,4-triazolyl)adamantanes by the reaction of 1,3-dibromoadamantane with 1,2,4-triazole in the absence of solvent is reported. The products, namely 1,3-bis(1,2,4-triazol-1-yl)adamantane and 1-(1,2,4-triazol-1-yl)-3-(1,2,4-triazol-4-yl)adamantane were separated by column chromatography and identified by NMR and mass-spectrometry.

The influence of fillers composition on microstructure, the physical and chemical properties of joints is studied. Thermal mismatch between fillers and Al 2 O 3 liners during laser joining process could be effectively reduced with the increase of MgO content. The mutual diffusion and the substitution reaction lead to the formation of the eutectic spinel phase (Mg, Fe)Al 2 O 4 . The interfacial atomic diffusion is enhanced by the addition of MgO. The joints corresponding to fillers composed of 70 wt.% Al 2 O 3 -15 wt.% MgO-15 wt.% SiO 2 have the optimal mechanical performance. The average flexural strength of joints reaches 168 Mpa which is 80% of the Al 2 O 3 liner (200Mpa). The weight loss of the joint interlayer in 10 wt.% HCl (pH = 0.45) for 24 h is 0.62 mg/cm 2 which is 0.16 mg/cm 2 lower than that of the liner. The softening temperature of joint interlayer exceeds 1500 °C. The reliability of Al 2 O 3 -lined joints could be maintained during the sequential process of arc welding for outer steel pipe layers. The corrosion of pipe layers could be effectively avoided. [ABSTRACT FROM AUTHOR]