Synthesis of Helical-Shaped Axially Chiral Bisoxime Ethers via Chiral Phosphoric-Acid-Catalyzed Sequential Enantioselective Condensations

A successful synthesis of helical-shaped axially chiral bisoxime ethers is reported. This approach utilized symmetric L-shaped diketone scaffolds as carbonyl components for the enantioselective condensation with hydroxylamines, delivering dual axially chiral oxime ethers with up to 99% ee. Additionally, the axially chiral mono-oxime ethers of azabicyclic ketones with high ee's were also successfully produced. Various chiral bicyclic lactams can be readily synthesized via Beckmann rearrangement, demonstrating a potential application in organic synthetic chemistry.

Visible-Light-Induced Radical Cascade Cross-Coupling via C(sp3)-H Activation and C-N/N-O Cleavage: Feasible Access to Methylenebisamide Derivatives

Here we report facile and manipulable access to methylenebisamide derivatives via visible-light-driven radical cascade processes incorporating C(sp³)-H activation and C-N/N-O cleavage. Mechanistic studies reveal that a traditional Ir-catalyzed photoredox pathway and a novel copper-induced complex-photolysis pathway are both involved, contributing to activating the inert N-methoxyamides and rendering the valuable bisamides. This approach exhibits many advantages, including mild reaction conditions, broad scope and functional group tolerance, and competitive step economy. Given the mechanistic plenitude and operational simplicity, we believe this package deal paves a promising way for the synthesis of valuable nitrogen-containing molecules.

In-situ synthesis of novel dual S-scheme AgI/Ag6Mo7O24/g-C3N4 heterojunctions with tandem structure for photocatalytic degradation of organic pollutants

The controllable design of multivariate heterojunction with sequential structures is of significant relevance for breaking the performance limit of binary composite photocatalysts. In this work, the novel dual S-scheme ternary-component AgI/Ag₆Mo₇O₂₄/exfoliated g-C₃N₄ (ECN) composite was prepared by a two-step in-situ synthetic strategy. The energy band bending at the heterointerface and the formation of dual built-in electric field could be observed due to distinct work functions of different components in the ternary composite. Benefiting from the sequential heterojunction structure, the AgI/Ag₆Mo₇O₂₄/ECN composite achieved 98.7% removal efficiency of 2-nitrophenol (2-NP) within 70 min under visible light irradiation, and AgI/Ag₆Mo₇O₂₄/ECN also showed higher degradation efficiency for a variety of organic pollutants such as methylene blue (MB), rhodamine B (RhB), methyl orange (MO), 4-nitrophenol (4-NP), 2-sec-butyl-4,6-dinitrophenol (DNBP) and tetracycline (TC). Notably, •OH and •O₂^- played dominant roles in the AgI/Ag₆Mo₇O₂₄/ECN set up, which was consistent with the dual S-scheme charge transfer mechanism. In-depth insights for the photodegradation of 2-NP were presented based on a combined DFT study and GC-MS analysis. Additionally, the photoreduction of Ag⁺ in AgI/Ag₆Mo₇O₂₄/ECN was also evaded by the fast transfer of photogenerated electrons through the dual S-scheme pathway, achieving the effect of killing two birds with one stone.

In Situ Construction of Dye-Sensitized BiOCl/Rutile-TiO2 Nanorod Heterojunctions with Highly Enhanced Photocatalytic Activity for Treating Persistent Organic Pollutants

The construction of efficient and stable heterojunction photocatalysts with a controllable close contact interface and visible-light response is a challenging research topic in the field of photocatalysis. Herein, a series of BiOCl/rutile-TiO₂ (R-TiO₂) nanorod heterojunctions were constructed using R-TiO₂ nanorods as supporting frameworks followed by selective adsorption of Cl^- on R-TiO₂(110) facets and in situ growth of BiOCl on the surface of TiO₂ nanorods. The strong affinity of rhodamine B (RhB) as a photosensitizer for BiOCl allowed the prepared BiOCl/R-TiO₂ heterojunctions to work efficiently under visible-light irradiation. The dye-sensitized BiOCl/R-TiO₂ nanorod heterojunctions displayed promising photocatalytic performance for simultaneously treating RhB and the persistent organic pollutant 2-sec-butyl-4,6-dinitrophenol (DNBP). The highly enhanced photodegradation activity of the BiOCl/R-TiO₂ system was mainly attributed to the efficient RhB-photosensitization effect, the enhanced heterojunction effect, and the suitable conduction band match between BiOCl and R-TiO₂, which facilitated electron transfer from the excited RhB to the catalyst surface and charge separation across the BiOCl/R-TiO₂ interface, thus promoting the formation of ^•O₂^- and h⁺ as dominant active species in the reaction system for degradation of pollutants. The results demonstrate that the construction of a dye-sensitized BiOCl/R-TiO₂ heterojunction system is an effective strategy for improving the photocatalytic potential.

The Photocatalyst-Free Cross-Dehydrogenative Coupling Reaction Enabled by Visible-Light Direct Excitation of Substrate

A new photocatalyst-free strategy for the cross-dehydrogenative C-C and C-P coupling reaction has been described. This protocol provides a concise method to synthesize various 1-substituted tetrahydroisoquinoline (THIQ) derivatives enabled by visible-light direct excitation of substrates without using any photocatalyst. Moreover, a wide substrate scope demonstrated good synthetic versatility and practicality.

Preparation of polydopamine nanocapsules in a miscible tetrahydrofuran–buffer mixture

A non-emulsion soft template method based on a miscible tetrahydrofuran–tris buffer mixture has been used to fabricate polydopamine nanocapsules.

Study on the treatment of 2-sec-butyl-4,6-dinitrophenol (DNBP) wastewater by ClO2 in the presence of aluminum oxide as catalyst

The chlorine dioxide (ClO(2)) oxidative degradation of 2-sec-butyl-4,6-dinitrophenol (DNBP) in aqueous solution was studied in detail using Al(2)O(3) as a heterogeneous catalyst. The operating parameters such as the ClO(2) concentration, catalyst dosage, initial DNBP concentration, reaction time and pH were evaluated. Compared with the conventional ClO(2) oxidation process without the catalyst, the ClO(2) catalytic oxidation system could significantly enhance the degradation efficiency. Under the optimal condition (DNBP concentration 39 mg L(-1), ClO(2) concentration 0.355 g L(-1), reaction time 60 min, catalyst dosage 10.7 g L(-1) and pH 4.66), degradation efficiency approached 99.1%. The catalyst was used at least 8 cycles without any appreciable loss of activity. The kinetic studies revealed that the ClO(2) catalytic oxidation degradation of DNBP followed pseudo-first-order kinetics with respect to DNBP concentration. The ClO(2) catalytic oxidation process was found to be very effective in the decolorization and COD(Cr) reduction of real wastewater from DNBP manufacturing. Thus, this study showed potential application of ClO(2) catalytic oxidation process in degradation of organic contaminants and industrial effluents.

Oxidative degradation of dinitro butyl phenol (DNBP) utilizing hydrogen peroxide and solar light over a Al2O3-supported Fe(III)-5-sulfosalicylic acid (ssal) catalyst

A novel and efficient photo-Fenton catalyst of Fe(III)-5-sulfosalicylic acid (ssal) supported on Al(2)O(3) was prepared and characterized by FT-IR and TEM-EDX technique. A detailed investigation of photocatalytic degradation of 2-sec-butyl-4,6-dinitrophenol (DNBP) using this catalyst and H(2)O(2) under solar light irradiation was carried out. The effects of reaction parameters on photodegradation performance were investigated by examining H(2)O(2) dosage, catalyst loading, solution pH, initial DNBP concentration and temperature. The optimal conditions were an initial DNBP concentration of 40 mg L(-1) at pH 2.5 and temperature 30 degrees C with catalyst loading of 1.0 g L(-1) and H(2)O(2) concentration of 5 mmol L(-1) under solar light irradiation for 100 min. Almost complete degradation of DNBP was observed with [Fe(III)-ssal]-Al(2)O(3)/H(2)O(2) process under the optimal conditions. The degradation of DNBP by photo-Fenton-type process can be divided into the initiation phase and the fast phase. The kinetics of Fenton oxidation is complex and the degradation of DNBP in the two phases both can be described by a pseudo-first-order kinetic model. No obvious decline in efficiency of the [Fe(III)-ssal]-Al(2)O(3) catalyst was observed after 5 repeated cycles indicating this catalyst is stable and reusable. A possible reaction mechanism was proposed on the basis of all the information obtained under various experimental conditions.

Facile synthesis of amide and amine derivatives of 2,2,3,3-tetramethylcyclopropanecarboxylic acid

An efficient one-pot procedure for the synthesis of amide derivatives of 2,2,3,3-tetramethylpropanecarboxylic acid (TMCA) that involves the treating of TMCA in N,N-dimethylacetamide (DMAC) with thionyl chloride and stoichiometric amounts of reactant amines has been developed. The combined reagent TiCl4/NaBH4 was found to be effective for the reduction of the amide derivatives of TMCA to the corresponding amines.

Solar photocatalytic degradation of 2,6-dinitro-p-cresol (DNPC) using multi-walled carbon nanotubes (MWCNTs)-TiO(2) composite photocatalysts

Multi-walled carbon nanotubes (MWCNTs)-TiO(2) composite photocatalysts with excellent activity were prepared by sol-gel method in order to investigate its photocatalytic activity under solar irradiation for the degradation of 2,6-dinitro-p-cresol (DNPC) in aqueous solution. The prepared composite were analyzed by XRD, FTIR, SEM, TEM, TG-DTA and UV-vis absorption spectra techniques. The results showed that the composite can cause an obvious red shift of UV-vis spectra compared with pure TiO(2). The degradation of DNPC by MWCNTs-TiO(2) composite photocatalysts under solar irradiation was systematically studied by varying the experimental parameters such as pH value, irradiation time, the initial substrate concentration, reaction temperature, catalyst concentration, etc. The optimal conditions were a DNPC concentration of 33.4 mgL(-1) at pH 6.0 with MWCNTs-TiO(2) concentration of 6.0gL(-1) under solar irradiation for the illumination of 150 min. The presence of MWCNTs can enhance the photoefficiency of TiO(2). The highest efficiency on photodegradation of DNPC can be achieved with an optimal MWCNTs/TiO(2) mass ratio of 0.05%. The photocatalytic degradation of DNPC obeys a pseudo-first-order behavior according to the Langmuir-Hinshelwood model, and possible decomposing mechanisms are also discussed. The photocatalyst was used for five cycles with photocatalytic degradation efficiency still higher than 96%. The results of the study showed the feasible and potential use of MWCNTs-TiO(2) composite in degradation of toxic organic pollutants.

Photocatalytic degradation of 2,4-dinitrophenol (DNP) by multi-walled carbon nanotubes (MWCNTs)/TiO2 composite in aqueous solution under solar irradiation

Nanosized multi-walled carbon nanotubes (MWCNTs)/TiO2 composite and neat TiO2 photocatalysts were synthesized by sol-gel technique using tetrabutyl titanate as a precursor. The as prepared photocatalysts were characterized using XRD, SEM, FTIR and UV-vis spectra. The samples were evaluated for their photocatalytic activity towards the degradation of 2,4-dinitrophenol (DNP) under solar irradiation. The results indicated that the addition of an appropriate amount of MWCNTs could remarkably improve the photocatalytic activity of TiO2. An optimal MWCNTs:TiO2 ratio of 0.05% (w/w) was found to achieve the maximum rate of DNP degradation. The effects of pH, irradiation time, catalyst concentration, DNP concentration, etc. on the photocatalytic activity were studied and the results obtained were fitted to the Langmuir-Hinshelwood model to study the degradation kinetics. The optimal conditions were an initial DNP concentration of 38.8 mg/L at pH 6.0 with catalyst concentration of 8 g/L under solar irradiation for 150 min with good recyclisation of catalyst. The degree of photocatalytic degradation of DNP increased with an increase in temperature. The MWCNTs/TiO2 composite was found to be very effective in the decolorization and COD reduction of real wastewater from DNP manufacturing. Thus, this study showed the feasible and potential use of MWCNTs/TiO2 composite in degradation of various toxic organic contaminants and industrial effluents.

Improved synthesis of 6-(4-methoxyphenyl)-2,4-dichloro-1,3,5-triazine and 2,4-bis(resorcinyl)-substituted UV light absorbing derivatives

Pure 6-(4-methoxyphenyl)-2,4-dichloro-1,3,5-triazine was synthesised by a method that did not involve the troublesome Grignard reaction of 4-bromo-anisole. A series of bis(resorcinyl) triazine derivatives which can be used as UV light absorbers were subsequently prepared by utilising 6-(4-methoxyphenyl)-2,4-dichloro-1,3,5-triazine as the starting material via alkylation or acid-catalysed addition reactions.