Reaction Of Formaldehyde Research Articles

The effect of urea-formaldehyde adhesive modification with propylamine on the properties of manufactured plywood

ABSTRACT The aim of the study was to investigate the effect of propylamine addition to urea-formaldehyde resin on the properties of resultant plywood. The research consisted in investigating the properties of both liquid and cured resins, as well as the produced plywood. Studies have shown that the incorporation of propylamine adversely affected reactivity of the adhesive mixtures by increasing their pH. The evaluation of adhesive chemical structure with FTIR spectroscopy showed some slight changes indicating the reaction of formaldehyde with introduced modifier. The addition of propylamine contributed to the considerable reduction of free formaldehyde contained in the cured adhesive. Furthermore, the propylamine was also found to work effectively as a formaldehyde scavenger by significantly reducing the hazardous emission from plywood. However, based on the results of bonding quality, delamination, bending strength and modulus of elasticity it was found that application of propylamine resulted in a noticeable deterioration of plywood properties. Therefore, the amount of introduced modifier should not exceed 1% of solid UF resin.

Strecker Reactions of Formaldehyde with TMSCN, Catalyzed by TBAF and Formic Acid: N‐Monocyanomethylation of Primary Amines

AbstractA set of conditions for the Strecker reaction of formaldehyde, amines, and TMSCN that affords three‐component coupling adducts as the major products is reported. HCOOH and TBAF are used as cocatalysts and the TMSCN functions as both cyanide source and protecting reagent for amines. As a result, the side reactions were suppressed efficiently and a broad range of aromatic and aliphatic amines were mono‐cyanomethylated in 52–99% yield. Furthermore, this protocol was successfully applied toward the synthesis of meta‐diamide insecticides.magnified image

Toward abiotic sugar synthesis from CO2 electrolysis

Toward abiotic sugar synthesis from CO2 electrolysis

Design of a New Hydrazine Moiety-Based Near-Infrared Fluorescence Probe for Detection and Imaging of Endogenous Formaldehyde In Vivo.

Formaldehyde (FA), the smallest molecular aldehyde with strong reducing properties, could regulate body homeostasis endogenously during physiological and pathological processes. The effective near-infrared (NIR) fluorescent probe is needed as a visualizer of FA in biologic organisms. In this work, a novel NIR fluorescent Probe-NHNH2 was designed on the basis of Probe-NH2 via introducing a strong nucleophilic hydrazine group, which can be used as a quenching and recognizing moiety for the detection of FA. With the treatment of FA, the hydrazine group of Probe-NHNH2 undergoes condensation and achieves a turn-on NIR fluorescence signal at a wavelength of 706 nm. The spectroscopic performance of Probe-NHNH2 for FA was evaluated, and it exhibited high sensitivity and selectivity for the detection of FA in solution. Moreover, compared to the amine moiety-based Probe-NH2, which our group reported, we found that hydrazine moiety-based Probe-NHNH2, exhibited a better reaction time of within 10 min and a lower detection limit of 0.68 μM, reflecting that the reaction of FA with hydrazine moiety is faster and more sensitive than that of FA with the amino group. More importantly, Probe-NHNH2 was successfully applied to real-time imaging of endogenous FA by reacting with effective stimulant tetrahydrofolate and scavenger sodium bisulfite in zebrafish and mice. It is expected that we can provide a new rapid, sensitive NIR fluorescence theoretical basis for FA detection and in vivo imaging applications.

Novel Novolac Phenolic Polymeric Network of Chalcones: Synthesis, Characterization, and Thermal-Electrical Conductivity Investigation.

A series of novolac phenolic polymeric networks (NPPN) were prepared via an acid-catalyzed polycondensation reaction of formaldehyde with chalcones possessing a p-phenolic OH group. When p-hydroxybenzaldehyde was treated with formaldehyde under the same conditions, a phenolic polymer (PP) was obtained. The resulting polymers were isolated in excellent yields (83–98%). Isolated polymers (NPPN, PP) were characterized using FTIR, TGA, and XRD. The results obtained from the TGA revealed that all prepared phenolic polymers have high thermal stability at high temperatures and can act as thermosetting materials. XRD data analysis showed a high degree of amorphousness for all polymers (78.8–89.2%). The electrical conductivities and resistivities of all chalcone-based phenolic networks (NPPN) and p-hydroxybenzaldehyde polymer (PP) were also determined. The physical characteristics obtained from the I-V curve showed that the conductivity of phenolic polymers has a wide range from ultimately negligible values of 0.09 µS/cm up to 2.97 μS/cm. The degree of polarization of the conjugated system’s carbonyl group was attributed to high, low, or even no conductivity for all phenolic polymers since the electronic effects (inductive and mesomeric) could impact the polarization of the carbonyl group and, consequently, change the degree of the charge separation to show varied conductivity values.

Evaluation of glycolaldehyde as a formaldehyde substitute in urea-based wood adhesives

Glycolaldehyde, produced from cracking of glucose, was tested as a substitute for formaldehyde in urea-based wood adhesives. Initially, different parameters (water content, aldehyde/urea-ratio, curing temperature, and time) were screened to identify the optimal curing conditions providing the highest bond strength. Afterwards, the system was reformulated as a 2-component system and compared to a urea-formaldehyde 2-component system, which showed a comparatively low strength of the resulting resin. Different hardeners were tested, and AlCl3 showed an 80% increase in bond strength for the resin compared to NH4Cl. Infrared and nuclear magnetic resonance analyses were performed to ensure formation of the desired aminal bond network, which showed that the hardener was essential for proper curing of the resin. Finally, a urea-glycolaldehyde-formaldehyde resin was tested that further indicated major differences between the reactivity of formaldehyde and glycolaldehyde.

Antioxidant Properties of Larch Tannins with Different Mean Polymerization Degrees: Controlled Degradation Based on Hydroxyl Radical Degradation.

Hydroxyl radical produced by hydrogen peroxide decomposition under UV radiation was used to degrade larch tannins in an environmentally friendly manner. The formaldehyde reactivity of the degraded products was used as an index to control the mean degree of polymerization (mDP) of the degraded products, and the effects of different mDP on the antioxidant activity of tannins were studied. Results showed that hydroxyl radical could significantly reduce the degree of polymerization (DP) and molecular weight (Mw) of larch tannins, and the mDP and Mw of degraded products could be controlled by considering the formaldehyde reactivity as the index. The antioxidant activity of larch tannins increased with the decrease in mDP. When the degradation time was 6 h, the formaldehyde reactivity was the highest at 0.823. The antioxidant activity of the degraded product was excellent, and the free radical scavenging rate was more than 98%.

Effect of Fe3O4 nanoparticles on magnetic xerogel composites for enhanced removal of fluoride and arsenic from aqueous solution

Fe3O4 magnetic xerogel composites were prepared by polycondensation of resorcinol (R)–formaldehyde reaction via a sol–gel process in an aqueous solution through varying the molar ratio of Fe3O4 nanoparticles (MNPs), catalyst (C), and water (W) content. MNPs were obtained by co-precipitation (MC), oxidation of iron salts (MO), or solvothermal synthesis (MS). Both MNPs and magnetic xerogels were examined regarding the performance of arsenic and fluoride removal in a batch system. The MC-based MNPs had higher adsorption capacities for both fluoride (202.9 mg/g) and arsenic (3.2 mg/g) than other MNPs in optimum conditions. The X-ray diffraction, Fourier transform infrared spectroscopy, and energy-dispersive X-ray spectroscopy confirmed that Fe was composed into the polymeric matrix of magnetic xerogels that contained 0.59%–4.42% of Fe with a molar ratio of MNPs (M) to R between 0.01 and 0.10. With low R/C and optimum M/R ratios, an increase in the surface area of magnetic xerogels affected the fluoride and arsenic adsorption capacities. The magnetic xerogel composites with the MC-based MNPs prepared at a fixed R/C ratio (100) and at different R/W (0.05–0.06) and M/R (0.07–0.10) ratios had a high arsenic removal efficiency of 100% at an As(V) concentration of 0.1 mg/L and pH of 3.0. The maximum adsorption capacities of magnetic xerogels were approximately five times higher than those of the xerogels without MNP composites. Therefore, Fe3O4 nanoparticles enhanced the adsorption of arsenate and fluoride. The variations of alkaline catalyst and water content significantly affected the resulting properties of textural and surface chemistry of magnetic xerogel composites.

Important Routes for Methanediol Formation by Formaldehyde Hydrolysis Catalyzed by Iodic Acid and for the Contribution to an Iodic Acid Sink by the Reaction of Formaldehyde with Iodic Acid Catalyzed by Atmospheric Water

Important Routes for Methanediol Formation by Formaldehyde Hydrolysis Catalyzed by Iodic Acid and for the Contribution to an Iodic Acid Sink by the Reaction of Formaldehyde with Iodic Acid Catalyzed by Atmospheric Water

A novel and environmentally friendly NASICON-type material: Efficient catalyst for condensation of formaldehyde and acetic acid to acrylic acid and methyl acrylate

The development of environmentally friendly and efficient catalysts for the production of essential chemicals has always been a desirable goal for technology in the chemical industry. In this paper, we fabricated a kind of sodium (Na) super ionic conductor (NASICON)-type materials (H1-xTi2(PO4)3-x(SO4)x) with different Ti/P ratios through tuning titanium content in synthetic mother liquor, and applied them to the aldol condensation reaction of acetic acid (HAc) and formaldehyde (FA) to acrylic acid (AA) and methyl acrylate (MA), which has never been not reported in previous researches. More importantly, these novel catalysts have showed their tremendous potential at the efficiency of AA + MA production, and over an optimized catalyst of NSC-Ti/P-0.53, the AA + MA selectivity being 71% (HAc input-based) was achieved at 360 ℃ when the reactant with FA/HAc molar ratio of 5:1 was fed; whereas, a highest space–time-yield (STY) of target products (∼37.2 μmol·g−1·min−1) was obtained with the FA/HAc molar ratio of 1:2.5, which is comparable to the best result reported previously. The detailed analysis of characterizations demonstrated that the change in the Ti/P ratio in the series NASICON catalysts led to the variation in the phase composition, the textural properties, surface titanium oxidation state, etc. thereby tuning the surface acid-base property, which is quite important for the present condensation reaction. More amounts of acidic sites and basic sites as well as their moderate distribution were proved to exert the promotional effects on the formation of AA and MA.

Construction of Complex Macromulticyclic Peptides via Stitching with Formaldehyde and Guanidine.

There is a growing interest in constructing multicyclic peptide structures to expand the chemical space of peptides. Conventional strategies for constructing large peptide structures are limited by the typical reliance on the inflexible coupling between premade templates equipped with fixed reactive handles and peptide substrates via cysteine anchors. Herein, we report the development of a facile three-component condensation reaction of primary alkyl amine, formaldehyde, and guanidine for construction of complex macromulticyclic peptides with novel topologies via lysine anchors. Moreover, the reaction sequences can be orchestrated in different anchor combinations and spatial arrangements to generate various macrocyclic structures crosslinked by distinct fused tetrahydrotriazine linkages. The macrocyclization reactions are selective, efficient, versatile, and workable in both organic and aqueous media. Thus, the condensation reaction provides a smart tool for stitching native peptides in situ using simple methylene threads and guanidine joints in a flexible and programmable manner.

Highly Active Palladium-Decorated Reduced Graphene Oxides for Heterogeneous Catalysis and Electrocatalysis: Hydrogen Production from Formaldehyde and Electrochemical Formaldehyde Detection.

The exploitation of highly efficient and stable hydrogen generation from chemical storage of formaldehyde (FA) is of great significance to the sustainable development of the future. Moreover, developing an accurate, rapid, reliable, and cost-effective catalyst for electrochemical detection of FA in solution is appealing. Herein, we report rational construction of Pd nanoparticles decorated reduced graphene oxides (Pd/rGO) nanohybrids not only as robust catalysts to produce hydrogen from alkaline FA solution and but also electrocatalysts for electrochemical detection of FA. By optimizing the reaction parameters including FA concentration, NaOH concentration and reaction temperature, Pd/rGO with Pd loading of 0.5 wt% could exhibit a high hydrogen production rate of 272 mL g−1min−1 at room temperature of 25 °C, which is 3.2 times that of conventional Pd NPs. In addition, as-prepared Pd/rGO nanohybrids modified glassy carbon (GC) electrodes are used as FA-detected electrochemical sensors. A sensitive oxidation peak with a current density of 8.38 mA/cm2 was observed at 0.12 V (vs. Ag/AgCl) in 0.5 M NaOH containing 10 mM FA over Pd/rGO catalysts with Pd loading of 0.5 wt%. The results showed the prepared Pd/rGO nanocatalyst not only exhibited efficient and stable hydrogen production from alkaline FA solution but also had good electrocatalytic properties with respect to formaldehyde electrooxidation as a result of the synergistic effect of Pd NPs and rGO nanosheets.

Cs2CO3-Promoted [3 + 2] Cyclization of Chalcone and N-Tosylhydrazone

Cs2CO3-promoted [3 + 2] cyclization of chalcone and N-tosylhydrazones has been developed, a series of novel (4,5-diaryl-1H-pyrazol-3-yl)(aryl)methanone derivatives were synthesized with a wide range of substrates, good tolerance of functional groups and by a one-pot three-component reaction of chalcone, aryl formaldehyde, and TsNHNH2. In addition, the gram-scale synthesis of the product and further transformations were also investigated.

Unique catalytic mechanisms of methanol dehydrogenation at Pd-doped ceria: A DFT+U study.

Pd-doped ceria is highly active in promoting oxidative dehydrogenation (ODH) reactions and also a model single atom catalyst (SAC). By performing density functional theory calculations corrected by on-site Coulomb interactions, we systematically studied the physicochemical properties of the Pd-doped CeO2(111) surface and the catalytic methanol to formaldehyde reaction on the surface. Two different configurations were located for the Pd dopant, and the calculated results showed that doping of Pd will make the surface more active with lower oxygen vacancy formation energies than the pristine CeO2(111). Moreover, two different pathways for the dehydrogenation of CH3OH to HCHO on the Pd-doped CeO2(111) were determined, one of which is the conventional two-step process (stepwise pathway) with the O-H bond of CH3OH being broken first followed by the C-H bond cleavage, while the other is a novel one-step process (concerted pathway) involving the two H being dissociated from CH3OH simultaneously even with a lower energy barrier than the stepwise one. With electronic and structural analyses, we showed that the direct reduction of Pd4+ to Pd2+ through the transfer of two electrons can outperform the separated Ce4+ to Ce3+ processes with the help of configurational evolution at the Pd site, which is responsible for the existence of such one-step dehydrogenation process. This novel mechanism may provide an inspiration for constructing ceria-based SAC with unique ODH activities.

Reactive adsorption and catalytic oxidation of gaseous formaldehyde at room temperature by a synergistic copper-magnesium bimetal oxide biochar composite

Formaldehyde molecules are actively adsorbed over the copper (glowing blue sphere)-magnesium (glowing green sphere)/biochar (black surface with cracks) to produce formate and carbon dioxide species. The synergistic interaction between copper and magnesium (as depicted by lightning) leads to the enhancement of the overall performance. • Cu-Mg/RH550 oxidized FA into CHOO – and CO 2 through reactive adsorption and catalysis. • Cu-Mg/RH550 showed a maximum adsorption capacity of 10 mg g −1 against 100 ppm FA. • Cu-Mg interaction in bimetallic form lowered their crystallite sizes to enhance activity. • The oxidation of adsorbed FA is expedited via partial reduction of Cu 2+ to Cu + . • Metal oxides host H of FA to make the oxidation reaction thermodynamically feasible. The interactive hybridization of reactive adsorption and catalytic oxidation (RACO) was investigated for the removal of formaldehyde (FA) by fine-tuning the relative compositions of bimetallic oxides between copper (Cu) and magnesium (Mg) on biochar (RH550). The best performer against 100 ppm FA was 8%-Cu-8%-Mg/RH550 when assessed in terms of 10% breakthrough volume (3 L atm g −1 ). The corresponding values for reference materials (e.g., RH550, 16%-Cu/RH550, and 16%-Mg/RH550) were 0.4, 1.1, and 0.5 L atm g −1 , respectively. Adsorption kinetic models confirmed the synergistic roles of physicochemical interactions between the target (FA molecules) and composite material (both organic (RH550) and inorganic (metal oxides) phases). The characterization of the spent Cu-Mg/RH550 suggests that the adsorbed FA molecules were partially oxidized into dioxymethylene and formate. Remarkably, Cu-Mg/RH550 led to the complete room-temperature mineralization of FA into carbon dioxide (CO 2 ) for up to 50 h time-on-stream (artificially set maximum test duration) without any deactivation (gas hourly space velocity of 2,229 h −1 ). The oxidation reaction of FA is expedited by the partial reduction of copper(II) oxide (in Cu-Mg/RH550) to copper(I) oxide. According to the density functional theory-based simulations, the metal oxides make the oxidation reaction thermodynamically favorable by hosting hydrogen abstracted from the adsorbed FA molecules. The Cu-Mg synergy also enhances the capture and activation of molecular oxygen (O 2 ) to boost FA oxidation while sustaining the catalytic process. Overall, this study offers new insights into the synergistic role of RACO in the effective removal of FA under ambient conditions.

A Discrete 3d–4f Metallacage as an Efficient Catalytic Nanoreactor for a Three-Component Aza-Darzens Reaction

The exploration and development of coordination nanocages can provide an approach to control chemical reactions beyond the bounds of the flask, which has aroused great interest due to their significant applications in the field of molecular recognition, supramolecular catalysis, and molecular self-assembly. Herein, we take the advantage of a semirigid and nonsymmetric bridging ligand (H5L) with rich metal-chelating sites to construct an unusual and discrete 3d-4f metallacage, [Zn2Er4(H2L)4(NO3)Cl2(H2O)]·NO3·xCH3OH·yH2O (Zn2Er4). The 3d-4f Zn2Er4 cage possesses a quadruple-stranded structure, and all of the ligands wrap around an open spherical cavity within the core. The self-assembly of the unique cage not only ensures the structural stability of the Zn2Er4 cage as a nanoreactor in solution but also makes the bimetallic lanthanide cluster units active sites that are exposed in the medium-sized cavity. It is important to note that the Zn2Er4 cage as a homogeneous catalyst has been successfully applied to catalyze three-component aza-Darzens reactions of formaldehyde, anilines, and α-diazo esters without another additive under mild conditions, displaying better catalytic activity, higher specificity, short reaction time, and low catalyst loadings. A possible mechanism for this three-component aza-Darzens reaction catalyzed by the Zn2Er4 cage has been proposed. These experimental results have demonstrated the great potential of the discrete 3d-4f metallacage as a host nanoreactor for the development of supramolecular or molecular catalysis.

Cesium Loaded on an Al-Modified Silica Support Catalyst for Methyl Acrylate Synthesis by Aldol Condensation of Methyl Acetate and Formaldehyde

An Al-modified silica-supported cesium catalyst was prepared by an incipient wetness impregnation method for the gas-phase aldol condensation reaction of methyl acetate and formaldehyde. The effect of the Al-modified silica support on the structure, specific surface area, and the acid property was studied using X-ray diffraction, Fourier transform infrared spectroscopy, N2 adsorption–desorption, NH3-temperature programmed desorption, X-ray photoelectron spectroscopy, and Py-IR. Adding the cesium species, the Cs–Al/SiO2 catalyst performed well based on the evaluation results in a fixed-bed reactor. A combination of these characterization and testing results manifests the influence of acid–base properties on the catalytic activity. It was found that the selectivity was related to the amount of weak acid sites and medium-strong base sites. The highest selectivity of methyl acrylate (MA) was obtained at T = 355 °C, LHSV = 0.6 h–1, and Ma/FA/MeOH molar ratio = 1:1:2 over the 10% Cs–3% Al/SiO2 catalyst. Finally, the performance of the optimized catalyst did not exhibit an obvious decrease via three times in situ regeneration.

Synthesis of 1,3-Propanediol by Cross Aldol Reaction and Hydrogenation of Formaldehyde with Acetaldehyde

Synthesis of 1,3-Propanediol by Cross Aldol Reaction and Hydrogenation of Formaldehyde with Acetaldehyde

Synthesis characterization and application of hexafunctional epoxy resin and comparison against commercial epoxy resin

Current study compares the various analytical results of hexafunctional epoxy resins based on bisphenol-A with conventional epoxy resins. Reaction of bisphenol-A, formaldehyde, and epichlorohydrin produces hexafunctional epoxy resin. The curing properties of commercial epoxy resin and hexafunctional epoxy resin were determined using a variety of hardeners, including diethylenetriamine, triethylenetetramine, phenalkamine, polyamido amines, and polyamides. The epoxy equivalent weight (EEW), hydrolyzable chlorine content, volatile content, Brookfield viscosity, weight average molecular weight, elemental analysis (C, H, N, O analysis), and Fourier transform infrared spectroscopy were used to characterize the hexafunctional resin (FT-IR). Jute and glass reinforced composites were also prepared by using hexafunctional epoxy resins and commercial epoxy resins. Mechanical properties (tensile strength, flexural strength, Izod impact strength, and Rockwell hardness), thermal properties, and chemical resistance were determined for each composite. Hexafunctional epoxy resin-based composites exhibited superior mechanical characteristics, thermal resistance, and chemical resistance properties than commercial epoxy resin-based composites.

Nano-sized H-ZSM-5 zeolite catalyzes aldol condensation reaction to prepare methyl acrylate and acrylic acid

An efficient and long-term stable nano-sized N-H-ZSM-5 zeolite catalyst for the one-step aldol condensation reaction of formaldehyde and MAc to produce MA and AA is reported. Its total lifetime reaches up to 226 h by three regeneration runs.