Synthesis Of Methylamines Research Articles

Theoretical study of tandem catalysts based on metal porphyrin-phthalocyanine two-dimensional carbon-rich conjugated frameworks for the co-reduction of NO3− and CO2 in the electrosynthesis of methylamine

Electrocatalytic NO3− and CO2 co-reduction to synthesize methylamine can remove NO3− and CO2 pollutants and produce valuable methylamine. However, the catalytic mechanism of electrocatalytic NO3− and CO2 co-reduction for the synthesis of methylamine is not sufficiently understood, and this research remains challenging. To supply the catalytic mechanism needed to create effective electrocatalysts, we systematically investigated the performance of metal-extended phthalocyanine and metalloporphyrin tandem catalysts to produce methylamine electrocatalytically through the co-reduction of NO3− and CO2 and found that the MoCo-Pc-Pt-N5Por COFs, MoNi-Pc-Pt-N5Por COFs, and MoRu-Pc-Pt-N5Por COFs were the most effective electrocatalysts. Also, we found that the metallic TM atoms in the catalysts with the NO3− and CO2 molecules with the coexistence of charge depletion and charge accumulation behavior as the activation mechanism of NO3− and CO2. This work offers a theoretical foundation for experimental research and opens up new possibilities for the rational design of effective electrocatalytic NO3− and CO2 co-reduction catalysts for synthesizing methylamine.

One-pot two-step reduction of CO2 with amines and NaBH4 to N-substituted compounds at atmospheric pressure

In this paper, the reductive N-formylation, methylation and cyclization of amines with carbon dioxide (CO2) using sodium borohydride (NaBH4) at atmospheric pressure, via a one-pot two-step procedure, is presented. Formato borohydride (NaBHn(OCHO)4-n), in situ formed in the reaction of NaBH4 with CO2, as an efficient agent to promote the corresponding reaction, and the mechanism is proposed on the basis of experiments. This wide substrate scope and simple operational methodology also facilitates the effective synthesis of formamides, methylamines, benzimidazoles and other heterocyclic compounds avoiding high temperature and pressure.

Fluoride-free synthesis of high-silica RHO zeolite for the highly selective synthesis of methylamine

High-silica RHO zeolites with high MMA plus DMA yield in methylamine synthesis were synthesized via interzeolite conversion of SSZ-13 with less OSDA and fluoride-free conditions. The d8r units of RHO were formed by s8r units of decomposed SSZ-13.

Synthesis of stable ECR-18 zeolite and its catalytic properties in methanol amination

ECR-18 is the synthetic analog of paulingite (framework type PAU), a naturally-occurring cage-based, small-pore zeolite. Because of its high framework Al content (Si/Al ∼ 3), this third generation of the RHO family of embedded isoreticular zeolites is structurally unstable, thereby hampering any catalytic application. Here we present the synthesis of ECR-18 with Si/Al ratios up to 4.4 using N-methyltropinium as an organic structure-directing agent and Na+ and/or K+ as inorganic structure-directing agents. The proton form of ECR-18 with Si/Al = 4.4 was found to retain the structural integrity. The catalytic properties of this ECR-18 for methylamines synthesis from ammonia and methanol have been compared with those of H-rho and H-PST-29, the two most selective catalysts for this reaction. Despite the similarity in acidity, H-ECR-18 showed a low sum yield of monomethylamine and dimethylamine compared to H-PST-29, mainly due to the lower ratio of scaffold (i.e., lta, pau, d8r, and t-plg) cages to embedded (i.e., t-oto, t-gsm, and t-phi) cages per unit cell of the former zeolite catalyst.

Computational Insights on Electrocatalytic Synthesis of Methylamine from Nitrate and Carbon Dioxide

Computational Insights on Electrocatalytic Synthesis of Methylamine from Nitrate and Carbon Dioxide

Controlled methylamine synthesis in a membrane reactor featuring a highly steam selective K+-LTA membrane

Water permeation through a hydrophilic zeolite membrane can be used to promote reactions under equilibrium controlled conditions through the in situ removal of the by-product water. In the methylamine synthesis, mono- (MMA), di- (DMA) and trimethylamine (TMA) are formed by the successive methylation of ammonia with methanol (MeOH) over a mildly acidic catalyst. The methylamine yield can be increased through selective water extraction from the reactor through a membrane. Since both reactants and water have similar molecular kinetic diameters below 3.7 Å, because of the limited steam selectivity of the commonly used hydrophilic Na-LTA membrane (zeolite 4A), not only water has been removed. Therefore, in this work a K-LTA membrane, which was obtained by ion exchange with a reduced pore window diameter of 3 Å and thus with a higher water selectivity, was used in the membrane-supported methylamine synthesis. When replacing the Na-LTA with the K-LTA membrane, the H2O/MeOH mixed gas separation factor increases up to 1100 and the H2O/NH3 separation could also be improved. This in turn leads to an overall boost of the higher methylated amines DMA and TMA in methylamine synthesis. When using the narrow-pore aluminosilicate catalyst H-SSZ-13 with CHA structure, the application of the K-LTA membrane increases the share of the industrially desired product DMA from 51% without membrane to 74% with slightly increased conversion. When using the large-pore catalyst H-MOR, the thermodynamically most stable product TMA can be formed and the selectivity was increased from 35% without membrane to 41% with the K-LTA membrane.

Exclusive SAPO-seeded synthesis of ZK-5 zeolite for selective synthesis of methylamines

ZK-5 zeolite with superior selectivity for monomethylamine (MMA) plus dimethylamine (DMA) is fast synthesized using the exclusive silicoaluminophosphate SAPO-34 seed and K+and Na+cations.

A comparative study of methylamines synthesis over zeolites H-rho and H-PST-29

A comparative study was performed not only on the proton form of rho and PST-29, the first and second generations of the RHO family of embedded isoreticular zeolites, respectively, but also on their steam-dealuminated analogues, as catalysts for methylamines synthesis at 400 °C from ammonia and methanol. A similar yield in the sum of monomethylamine plus dimethylamine was observed for H-rho and H-PST-29. Steam treatment at 600 °C gave both zeolites an increase in catalyst lifetime, but which is much more apparent in H-PST-29, probably due to a larger decrease in strength of medium and strong acid sites, together with the mesopore formation. Dealumianted PST-29 showed a somewhat lower catalyst stability than H-mordenite, the former commercial catalyst for this reaction. However, it was found to exhibit a much higher yield in smaller methylamines and a comparable regenerability. • H-rho, H-PST-29, and their steam analogues are tested for methylamines synthesis. • H-PST-29 showed a similar yield in monomethylamine plus dimethylamine to H-rho. • Steaming of H-rho and H-PST-29 resulted in an increase in the catalytic lifetimes. • The steamed PST-29 is potentially useful as a catalyst in methylamines synthesis.

Mitigation of Drought Stress Effects on Pepper Seedlings by Exogenous Methylamine Application

The study was conducted to determine effects of a new synthesis of methylamine on the plant growth, physiological and biochemical characteristics in pepper. There were four irrigation levels [full irrigation (100%) (I0), 80% (I1), 60% (I2) and 40% (I3)] and two methylamine (MA) treatments (0, 2.5 mM). At the end of the study, it was observed that there were significant differences between applications and levels. Effects of MA treatments on plant growth (plant height, stem diameter, fresh, dry weight etc.), plant physiological and biochemical parameters [tissue electrical conductivity (TEC), tissue relative water content (TRWC), hydrogen peroxide (H2O2), malondialdehyde (MDA), proline, antioxidant enzyme activity], and plant nutrient element content of pepper seedlings under different irrigation levels were significantly important. The results of the study showed that the drought stress conditions negatively affected the plant growth, increased the content of TEC, H2O2 and MDA, and decreased the TRWC and plant mineral content in pepper. However, MA application improved plant growth and decreased TEC, H2O2 and MDA content compared to control in pepper under drought conditions. MA treated plants at I3 had higher shoot fresh weight and shoot dry weight than non-treated plants by 12 and 20%, respectively. In conclusion, MA application could mitigate the deleterious effects of the drought stress on the pepper seedlings.

Mitigation of Drought Stress Effects on Pepper Seedlings by Exogenous Methylamine Application

The study was conducted to determine effects of a new synthesis of methylamine on the plant growth, physiological and biochemical characteristics in pepper. There were four irrigation levels [full irrigation (100%) (I0), 80% (I1), 60% (I2) and 40% (I3)] and two methylamine (MA) treatments (0, 2.5 mM). At the end of the study, it was observed that there were significant differences between applications and levels. Effects of MA treatments on plant growth (plant height, stem diameter, fresh, dry weight etc.), plant physiological and biochemical parameters [tissue electrical conductivity (TEC), tissue relative water content (TRWC), hydrogen peroxide (H2O2), malondialdehyde (MDA), proline, antioxidant enzyme activity], and plant nutrient element content of pepper seedlings under different irrigation levels were significantly important. The results of the study showed that the drought stress conditions negatively affected the plant growth, increased the content of TEC, H2O2 and MDA, and decreased the TRWC and plant mineral content in pepper. However, MA application improved plant growth and decreased TEC, H2O2 and MDA content compared to control in pepper under drought conditions. MA treated plants at I3 had higher shoot fresh weight and shoot dry weight than non-treated plants by 12 and 20%, respectively. In conclusion, MA application could mitigate the deleterious effects of the drought stress on the pepper seedlings.

Selective synthesis of formamides, 1,2-bis(N-heterocyclic)ethanes and methylamines from cyclic amines and CO2/H2 catalyzed by an ionic liquid-Pd/C system.

The reduction of CO2 with amines and H2 generally produces N-formylated or N-methylated compounds over different catalysts. Herein, we report the selective synthesis of formamides, 1,2-bis(N-heterocyclic)ethanes, and methylamines, which is achieved over an ionic liquid (IL, e.g., 1-butyl-3-methylimidazolium tetrafluoroborate, [BMIm][BF4])-Pd/C catalytic system. By simply varying the reaction temperature, formamides and methylamines can be selectively produced, respectively, in high yields. Interestingly, 1,2-bis(N-heterocyclic)ethanes can also be obtained via the McMurry reaction of the formed formamide coupled with subsequent hydrogenation. It was found that [BMIm][BF4] can react with formamide to form a [BMIm]+-formamide adduct; thus combined with Pd/C it can catalyze McMurry coupling of formamide in the presence of H2 to afford 1,2-bis(N-heterocyclic)ethane. Moreover, Pd/C-[BMIm][BF4] can further catalyze the hydrogenolysis of 1,2-bis(N-heterocyclic)ethane to access methylamine. [BMIm][BF4]-Pd/C was tolerant to a wide substrate scope, giving the corresponding formamides, 1,2-bis(N-heterocyclic)ethanes or methylamines in moderate to high yields. This work develops a new route to produce N-methylamine and opens the way to produce 1,2-bis(N-heterocyclic)ethane from cyclic amine as well.

SAPO-34 synthesized with n-butylamine as a template and its catalytic application in the methanol amination reaction

SAPO-34 was synthesized with n-butylamine (BA) as a template for the first time. Crystallization temperature and initial Si amount were important factors leading to successful syntheses. Lamellar AlPO-kanemite tends to form as the major phase or as an impurity of SAPO-34 at lower crystallization temperatures, though a higher initial Si amount may offer a positive effect on the crystallization of SAPO-34 that mitigates the low temperature. Higher temperature (240 °C) can effectively suppress the generation of lamellar materials and allow the synthesis of pure SAPO-34 with a wider range of Si incorporation. The crystallization processes at 200 and 240 °C were investigated and compared. We used the aminothermal method to synthesize SAPO-34-BA at 240 °C and also found n-propylamine is a suitable template for the synthesis of SAPO-34. The SAPO-34-BA products were characterized by many techniques. SAPO-34-BA has good thermal stability, crystallinity and porosity. BA remained intact in the crystals with ∼1.8 BA molecule per chabazite cage. The catalytic performance of SAPO-34 was tested in the methanol amination reaction, which showed high methanol conversion and selectivity for methylamine plus dimethylamine under the conditions investigated, suggesting that this material is a good candidate for the synthesis of methylamines.

Synthesis and analysis of aryl methyl amines

Synthesis and analysis of aryl methyl amines

Glycerol as a Building Block for Prochiral Aminoketone, N-Formamide, and N-Methyl Amine Synthesis.

Prochiral aminoketones are key intermediates for the synthesis of optically active amino alcohols, and glycerol is one of the main biomass-based alcohols available in industry. In this work, glycerol was catalytically activated and purposefully converted with amines to generate highly valuable prochiral aminoketones, as well as N-formamides and N-methyl amines, over CuNiAlOx catalyst. The catalyst structure can be anticipated as nano-Ni species on or in CuAlOx via the formation of nano- Cu-Ni alloy particles. This concept may present a novel and valuable methodology for glycerol utilization.

Metabolic Profile and Root Development of Hypericum perforatum L. In vitro Roots under Stress Conditions Due to Chitosan Treatment and Culture Time

The responses of Hypericum perforatum root cultures to chitosan elicitation had been investigated through 1H-NMR-based metabolomics associated with morpho-anatomical analyses. The root metabolome was influenced by two factors, i.e., time of culture (associated with biomass growth and related “overcrowding stress”) and chitosan elicitation. ANOVA simultaneous component analysis (ASCA) modeling showed that these factors act independently. In response to the increase of biomass density over time, a decrease in the synthesis of isoleucine, valine, pyruvate, methylamine, etanolamine, trigonelline, glutamine and fatty acids, and an increase in the synthesis of phenolic compounds, such as xanthones, epicatechin, gallic, and shikimic acid were observed. Among the xanthones, brasilixanthone B has been identified for the first time in chitosan-elicited root cultures of H. perforatum. Chitosan treatment associated to a slowdown of root biomass growth caused an increase in DMAPP and a decrease in stigmasterol, shikimic acid, and tryptophan levels. The histological analysis of chitosan-treated roots revealed a marked swelling of the root apex, mainly due to the hypertrophy of the first two sub-epidermal cell layers. In addition, periclinal divisions in hypertrophic cortical cells, resulting in an increase of cortical layers, were frequently observed. Most of the metabolic variations as well as the morpho-anatomical alterations occurred within 72 h from the elicitation, suggesting an early response of H. perforatum roots to chitosan elicitation. The obtained results improve the knowledge of the root responses to biotic stress and provide useful information to optimize the biotechnological production of plant compounds of industrial interest.

Heterogeneous PdAg alloy catalyst for selective methylation of aromatic amines with formic acid under an additive-free and solvothermal one-pot condition

The methylation of amines for the synthesis of methylamines and dimethylamines as platform chemicals has been attempted mostly by homogeneous catalysts with acid additives. However, there are scarcely any reports on heterogeneous catalytic methylation reactions except for a routine approach under high temperature and high pressure of CO2 and H2 gases for extended reaction times. Here we report a heterogeneously catalyzed selective methylation of aromatic amines using reactive and nontoxic formic acid as the only source for the construction of methyl groups, under ambient pressure in an additive-free one-pot reaction condition. Equal proportions of Pd and Ag in the PdAg/Fe3O4/N-rGO catalyst deliver highly selective amine methylation without aromatic ring hydrogenation, as the strained Pd in the alloy is combined with the graphene-derived support, preventing nanoparticle agglomeration and the action of magnetite as a promoter. Both N-methylation and N,N-dimethylation of various substituted aromatic amines were performed with complete conversion and excellent 90–97% selectivity by controlling the reaction times in the range of 10–24 h at 140 °C without unwanted aromatic ring hydrogenation. Furthermore, the developed bimetallic catalyst provided high yields (88–91%) of methylation with CO2+H2 gas under high pressure, which are as good as the results of homogenous catalysts with an acid additive. To the best of our knowledge, our use of this environmentally friendly methodology is the first time that this durable heterogeneous catalyst has readily performed highly selective methylation at ambient pressure, which is attractive for industrial applications. A heterogeneous palladium—silver alloy can catalyse selective methylation of aromatic amines under ambient pressure and without additives. Methylation of amines is used to manufacture chemicals used in fertilizers, fungicides, synthetic leathers and polymers. Formic acid, which is produced from biomass, is an environmentally friendly reagent for producing amines. Ajay Singh, Yoon-Ho Hwang and Dong-Pyo Kim at Pohang University of Science and Technology in Korea used a heterogeneous palladium—silver catalyst to selectively methylate aromatic amines at ambient pressure in a one-pot reaction that employs only formic acid as the source. They achieved complete conversion and high selectivities in the range 90–97% for methylation and dimethylation of various substituted aromatic amines. The catalyst realized yields comparable to those of homogenous catalysts with acid additives for methylation with carbon dioxide and hydrogen under high pressure. A heterogeneous palladium–silver alloy can catalyze selective methylation of aromatic amines under ambient pressure and without additives. Methylation of amines is used to manufacture chemicals used in fertilizers, fungicides, synthetic leathers and polymers. Formic acid, which is produced from biomass, is an environmentally friendly reagent for producing amines. They achieved complete conversion and high selectivities in the range 90–97% for methylation and dimethylation of various substituted aromatic amines only by formic acid as the source. The catalyst realized yields comparable to those of homogenous catalysts with acid additives for methylation with carbon dioxide and hydrogen under high pressure.

Investigation of the Strong Brønsted Acidity in a Novel SAPO-type Molecular Sieve, DNL-6

By applying analysis of multiple solid-state MAS NMR spectra, the atomic coordination environment and acidity of a novel SAPO-type molecular sieve, DNL-6, are studied. 27Al MQ-MAS NMR and 31P27Al MQ-HETCOR NMR spectra reveal the existence of a SiAlSi region with Al(OSi)n (n = 14) species in the framework of DNL-6, explaining well the high concentration of single Si(OAl)4 species (3 mmol/g) accommodated in the sample. 13C MAS NMR of 2-13C-acetone adsorption indicates that there exist two kinds of strong Bronsted acid sites in DNL-6. One of them has similar strength as those in HZSM-5 and the other is even stronger, which is unusual in SAPO-type molecular sieves. Also, a discrepancy in Bronsted acid concentration between the theoretical and 1H NMR experimental results has been found, revealing the occurrence of a dehydoxylation process during the calcination. The origin of the extremely strong Bronsted acid sites in DNL-6 is investigated by density functional theory calculations, which suggest that the dehydroxylation process may lead to a local structure deformation and remarkably enhance the Bronsted acidity. More importantly, DNL-6 exhibits excellent catalytic activity in the synthesis of methylamines due to its stronger acidity.

Selectivity-Controlling Factors in Catalytic Methanol Amination Studied by Isotopically Modulated Excitation IR Spectroscopy

Present mechanistic models for catalytic amination of methanol by zeolites focus on shape-selectivity of monomethylamine (MMA), dimethylamine (DMA), and trimethylamine (TMA) in the micropores. However, a rational explanation of the uniquely high selectivity to MMA and DMA achieved over Na+-exchanged mordenite (Na+-MOR) requires the consideration of additional selectivity-controlling factors. We have applied modulation–excitation diffuse reflectance IR Fourier transform spectroscopy with periodic perturbation by the isotope CD3OD to realize a chemically steady state but isotopically transient condition during methylamines synthesis from methanol and ammonia. These studies proved that the H-bonded network of methanol agglomerates and open dimers in the micropores can readily be replaced by NH3 at 623 K, probably leading to a decrease in the methanol concentration around catalytically active sites and, thus, suppressing the consecutive reaction of MMA to DMA and, finally, to TMA. Concentration modulation between NH3 and MMA indicated weaker adsorption of MMA, which was largely replaced by NH3 at the reaction temperature, thereby hindering further methylation of MMA.

ChemInform Abstract: Asymmetric Synthesis of (Triaryl)methylamines by Rhodium‐Catalyzed Addition of Arylboroxines to Cyclic N‐Sulfonyl Ketimines.

AbstractA new asymmetric addition of arylboroxines (II) to cyclic N‐sulfonyl ketimines (I) proceeds in the presence of a rhodium catalyst coordinated with a chiral diene ligand.

Asymmetric Synthesis of (Triaryl)methylamines by Rhodium-Catalyzed Addition of Arylboroxines to Cyclic N-Sulfonyl Ketimines

Asymmetric addition of arylboroxines to cyclic N-sulfonyl ketimines proceeded in the presence of a rhodium catalyst coordinated with a chiral diene ligand to give high yields of benzosultams, where a triaryl-substituted stereogenic carbon center was created with high enantioselectivity (93-99% ee). The chiral benzosultams were transformed into the chiral (triaryl)methylamines by breaking the cyclic structure.