Search

Substituted guanidines were synthesized by the guanylation of amines with carbodiimides using Zn-Al hydrotalcite (Zn-Al HT) catalyst. Zn-Al HT was prepared by co-precipitation method and characterized by X-ray powder diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Raman and Thermogravimetric-Differential Thermal Analysis (TG-DTA). The heterogeneous catalyst afforded moderate to good yields (∼50-60 %) of substituted guanidines in toluene at 110°C in 12 h. The catalyst was recovered quantitatively by simple filtration and reused for three cycles with consistent activity. The XRD and FTIR studies of the used catalyst shows no variation in the structure of the catalyst even after three recycles. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

ABSTRACT A highly efficient α-amination of branched aldehydes catalyzed by chiral imide monosubstituted 1,2-diamine derivatives was reported to afford the quaternary stereogenic centers in excellent yields (up to 99%) and (up to 97% ee). Chirality 25:668-672, 2013. © 2013 Wiley Periodicals, Inc [ABSTRACT FROM AUTHOR]

Abstract: A catalyst-free and convenient approach for the preparation of substituted dihydro-2-oxypyrrole is described. This three-component reaction between primary amines, dialkyl acetylenedicarboxylate, and N,N′-bis(phenylmethylidene)phenylmethane proceeds in MeOH under reflux conditions in good to excellent yields. [Copyright &y& Elsevier]

We report here a novel, one-pot, two-step reductive amination of aldehydes for the atom-economical synthesis of primary amines. The amination step has been carried out with hydroxylammonium chloride and does not require the use of a base. In the subsequent reduction step, a metal zinc/hydrochloride acid system has been used. This method is applicable to both aliphatic and aromatic aldehydes. The operational simplicity, the short reaction times, and the mild reaction conditions add to the value of this method as a practical alternative to the reductive amination of aldehydes. Supplemental materials are available for this article. Go to the publisher's online edition ofSynthetic Communications® to view the free supplemental file. [ABSTRACT FROM AUTHOR]

Abstract: Amination of lignin can bring reactive amino groups onto the natural polymer and enable it to be employed in engineering materials. The amination reaction was successfully implemented after some of the hydroxyl groups on lignin were epoxidized. The resulted products showed a great quantity of primary amine group and secondary amine group which can be used as curing agents of epoxy resin. The results revealed that several factors including reaction temperature and time, as well as ratios of compounds, could influence the epoxidation and amination reactions. The resulted products were characterized by FT-IR spectra, 1H NMR, 13C NMR, element analysis, XPS and thermogravimetry analysis. [Copyright &y& Elsevier]

The 1:1 imine intermediate generated by the addition of primary amine to chloroacetone derivatives is trapped byN-isocyaniminotriphenylphosphorane in the presence of phenylacetylenecarboxylic acid, leading to the formation of the corresponding iminophosphorane intermediate. Disubstituted 1,3,4-oxadiazole derivatives are formed via intramolecular aza-Wittig reaction of the iminophosphorane intermediate. The reactions were completed in neutral conditions at room temperature. The disubstituted 1,3,4-oxadiazole derivatives were prepared in excellent yields. Supplemental materials are available for this article. Go to the publisher's online edition ofSynthetic Communications®to view the free supplemental file. [ABSTRACT FROM AUTHOR]

ABSTRACT Crown ethers are capable of complexing with primary amines and have been utilized in chromatography to separate amino acid racemates. This application has been extended to resolve (1-amino-1-phenylmethyl)phosphonic acid and (1-aminoethyl)phosphonic acid racemates, along with their aminocarboxylic acid analogs (2-phenylglycine and alanine, respectively), via a ChiroSil RCA crown ether based chiral stationary phase. Effects of the organic modifier, temperature, and acid type and concentration on and selectivity were also investigated. Trends in and selectivity varied between aminophosponic acids and their aminocarboxylic analogs. and 1H NMR analyses were performed to potentially gain a better understanding of interactions of the aforementioned molecules with the ChiroSil RCA chiral stationary phase. Theoretical predictions of the most stable conformations for ( R)- and ( S)-enantiomers were compared to elution order; it was found that the elution order agreed with such that the longest correlated with the predicted most stable complex between the enantiomer and crown ether. 1H NMR demonstrated interactions of aminophosphonic and aminocarboxylic racemates with (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid in solution and was utilized to determine enantiomeric excess of (1-amino-1-phenylmethyl)phosphonic acid after its enantioenrichment via crystallization through diastereomeric salt formation with the crown ether followed by filtration. Chirality 25:369-378, 2013. © 2013 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

A new one-step synthesis of isonitriles is described. The starting materials are a primary amine, chloroform, sodium hydride, and the phase-transfer catalyst 15-crown-5 ether, and the solvent is benzene. Five compounds are used to illustrate the features of the new synthesis: 1-adamantyl isocyanide (2a), 2-adamantyl isocyanide (2b),cis-1,8-diisocyano-p-menthane (2c), 2,4,6-trimethylphenyl isocyanide (2d), and trityl isocyanide (2e). The present synthesis is superior to the existing published syntheses because of its yields are good, the by-products are innocuous (H2gas and NaCl), and its workup is simple. Supplemental materials are available for this article. Go to the publisher's online edition ofSynthetic Communications® to view the free supplemental file. [ABSTRACT FROM PUBLISHER]

1-Substituted 1 H-1,2,3,4-tetrazoles were efficiently synthesized from the reaction of primary amines, triethyl orthoformate, and sodium azide in presence of a catalytic amount of PO-SiO under conventional and ultrasound irradiation in solvent-free conditions. The advantages of this procedure are high yields, relatively short reaction times, ease of product isolation, low cost, and recovery and reusability of the catalyst. Graphical Abstract: [Figure not available: see fulltext.]. [ABSTRACT FROM AUTHOR]

Poly(vinyl amine) (PVAm) was derivatised using 2-thiophenecarboxaldehyde via Michael addition to prepare a statistical copolymer stabiliser for the synthesis of primary amine-functionalised polypyrrole (PPy) particles. A minimum stabiliser concentration of around 20 % (w/v) relative to pyrrole was required for well-defined PPy particles of approximately 100-200 nm, as judged by transmission electron microscopy (TEM) and dynamic light scattering (DLS). FTIR spectroscopy confirmed that stabiliser grafting had occurred, while x-ray photoelectron spectroscopy (XPS) studies indicated a stabiliser surface coverage on the PPy particles of around 53 %. PPy particles prepared at stabiliser concentrations below 20 % (w/v) were not colloidally stable above pH 6. However, higher stabiliser concentrations (e.g., 50 % (w/v) based on pyrrole) led to a significant improvement, with colloidal stability being retained above pH 7. Long-term colloidal stability studies of PPy particles stored at pH 7.5 confirmed that the amine-based stabiliser produced more stable aqueous dispersions than the imine-based stabiliser, since the latter bond is hydrolytically unstable. [ABSTRACT FROM AUTHOR]

A new and efficient method for the synthesis of N-substituted 3-oxoisoindoline-1-carbonitrile derivatives by a one-pot, three-component condensation reaction of 2-carboxybenzaldehyde, primary amine, and TMSCN in the presence of 10 mol % sulfamic acid (NH2SO3H) as the catalyst in EtOH under reflux temperature is described. The process is simple and environmentally benign and the catalyst is commercially available and inexpensive. [ABSTRACT FROM AUTHOR]

The formation of toxic nitrogenous disinfection byproducts (N-DBPs), such as nitrosamines, halonitromethanes and haloacetonitriles, from reactions between chlorine/chloramine and dissolved organic nitrogen in drinking water has caused great concern with regarding public health. This study revealed the occurrence of 17 aliphatic amines, some of which have been confirmed to be the precursors of N-DBPs, in source water across China. A sensitive method based on benzenesulfonyl chloride derivatization and liquid-liquid extraction followed by GC-MS analysis was established for the simultaneous analysis of the selected amines in aqueous samples. In total, 37 source water samples from the capital cities of 20 provinces were collected for the survey. Among the 17 amines, 14 were detected with an average frequency of detection of 36%. The most relevant amines in terms of frequency and maximum concentrations detected were dimethylamine (100%, 24.82 μg/L), methylamine (78%, 0.92 μg/L), N-methylethylamine (70%, 8.84 μg/L), propylamine (59%, 10.69 μg/L), diethylamine (54%, 3.76 μg/L), N-methylbutylamine (35%, 3.07 μg/L), N-ethylpropylamine (35%, 0.52 μg/L), and piperidine (32%, 2.35 μg/L). This is the first large scale survey of the aliphatic amines occurrence in source water in the world. The wide presence of nitrosamine precursors like dimethylamine, N-methylethylamine and diethylamine, and the precursors of haloacetonitriles and halonitromethanes like methylamine and propylamine suggests that better source water management is required to ensure the safety of drinking water. [ABSTRACT FROM AUTHOR]

Abstract: A new type of colloidal mesoporous silica nanoparticles (MSNs) is synthesized in liquid–liquid biphasic systems consisting of tetraethoxysilane (TEOS) and water in the presence of primary amines and cationic surfactants (cetyltrimethylammonium chloride, CTAC) under controlled pH conditions (pH 11.1–11.5). The obtained MSNs are characterized by scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), X-ray diffraction (XRD), and nitrogen adsorption–desorption. The results show that the colloidal MSNs with an average diameter in the range of 28–54nm and a size polydispersity below ca. 15% have been obtained. Importantly, each MSN is composed of a number of tiny primary silica nanoparticles (PSNPs) forming 3D connected pore structure. The pore size of the MSNs can be tuned from 2.5 to 3.0nm by changing the pH of catalyst stock solution, and larger pore sizes (3.1–4.5nm) can be achieved by using pore swelling agent. The Brunauer–Emmett–Teller (BET) surface areas and total pore volumes vary from 550 to 750m2 g−1 and from 1.2 to 1.7cm3 g−1, respectively. Compared with conventional MCM-41-type MSNs, our new MSNs show outstanding colloidal and hydrothermal stabilities. They are colloidally stable at room temperature over 1year, and their mesostructure was retained even after hydrothermal treatment at 120°C for 24h. Finally, based on the analysis of the morphology and structure of MSNs, a formation scheme based on the cooperative self-assembly of PSNPs and surfactant molecules is proposed. [Copyright &y& Elsevier]

An effective route to functionalized 5 H-spiro[furan-2,2′-indene]-1′,3′,5-triones is described via tandem reaction of primary amines, acetylenic esters and ninhydrin. [ABSTRACT FROM AUTHOR]

Abstract: A simple and efficient procedure has been developed for the synthesis of substituted pyrrole-fused isocoumarins from easily available ninhydrin. The cyclic hemiaminal dihydroxy-indenopyrroles, the adducts of ninhydrin with enamines of acetylacetone, give pyrrole-fused isocoumarins upon heating in acidic medium. The process constitutes an interesting acid-catalyzed rearrangement to eight-membered lactams followed by intramolecular cyclization involving the amino and keto groups. [Copyright &y& Elsevier]

Chiral cinchona alkaloid salts‐catalyzed asymmetric epoxidation of 2‐cyclohexen‐1‐one with hydrogen peroxide (H2O2) has been investigated using density functional theory (DFT). The ring‐closure step is rate limiting in the catalytic reaction. The enantioselectivity‐determining step is initial nucleophilic addition involving two orientations of axial and equatorial. In (S)‐catalyst j‐mediated process, axial pathway is favored over equatorial leading to the major epoxide [2S,3S]‐3. An opposite enantiomer [2R,3R]‐3 is primarily generated in (R)‐catalyst k‐assisted case preferring equatorial pathway. The results indicate that the enantioselectivity of epoxidation is dominated by central chirality of the bifunctional catalysts in the activation of enone by primary amine salt via iminium formation and of H2O2 by tertiary amine reacting as a general base. The substituent effect is also discussed to clarify a tendency existing in experiment. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011 [ABSTRACT FROM AUTHOR]

Abstract: Heterogeneous Ru/Re and Rh/Re catalysts, formed in situ from Ru3(CO)12/Re2(CO)10 and Rh6(CO)16/Re2(CO)10 respectively, are effective for the liquid phase hydrogenation of cyclohexanecarboxamide (CyCONH2) to CyCH2NH2 in up to 95% selectivity without the requirement for ammonia to inhibit secondary and tertiary amine formation. Good amide conversions are noted within the reaction condition regimes 50–100bar H2 and ⩾150 (Rh) – 160°C (Ru). Variations in Ru:Re and Rh:Re composition result in only minor changes in product selectivity with no evidence of catalyst deactivation at higher levels of Re. In situ HP-FTIR spectroscopy has shown that catalyst genesis occurs via decomposition of the metal carbonyl precursors. Ex situ characterization, using XRD, XPS and EDX-STEM, has provided evidence for the active components of these catalysts containing bimetallic Ru/Re and Rh/Re nanoclusters, the surfaces of which become significantly oxidized after use in amide reduction. Potential mechanistic pathways for amide hydrogenation are discussed, including initial dehydration to nitrile, a pathway potentially specifically accessible to primary amides, and evidence for often postulated imine intermediates. [Copyright &y& Elsevier]

Abstract: An easy, efficient, and simple one-pot approach for the synthesis of 1,3-thiazolidine-2-thiones via multicomponent reaction is reported. The reaction of a primary amine with carbon disulfide in the presence of dibenzoylacetylene or bis(4-methyl-1-benzoyl)acetylene in a mixture of CH2Cl2 and H2O after 5 h, afforded the title compound as alkene diastereomers. [Copyright &y& Elsevier]

Abstract: The removal of iron from industrial aluminum sulfate by the primary amine extraction system composed of primary amine N-1923 as the extractant, n-octanol as the modifier and kerosene as the diluent was studied. The mechanism of removing iron by primary amine system was determined through slope analysis method and IR spectra. Also investigated were effects such as pH in aqueous phase, phase ratios O/A (organic/aqueous), the volume fractions of extractant and modifier in organic phase, and the contact time of extraction. At the same time, the research was conducted on stripping of iron using sodium chloride solution or sulfuric acid as stripping agents from the iron-loaded organic phase. The results showed 99.99% extraction of iron from industrial aluminum sulfate with the extraction system composed of 25vol.% N-1923, 25vol.% n-octanol and 50vol.% kerosene when the phase ratio O/A was 1:2, pH value>1.2 and contact time was 6min. The difficulties in separating aqueous phase and organic phase were effectively overcome by n-octanol. The strip recovery of iron using 4.0molL−1 sulfuric acid as the stripping agent was 96.5% which was slightly higher than that using 2.0molL−1 sodium chloride. [Copyright &y& Elsevier]

Abstract: Experimentally found kinetic values (pseudo-first order rate constants) for the reaction of CO2 in different types of aqueous amines using stopped-flow technique were compared at 303.15 K. (Primary amines–1-amino-propanol(1-AP), 3-amino-propanol(3-AP),Ethylaminoethanol(EAE); Secondary amines–Ethylene diamine(EDA), 1, 3-diamino propane(DAP), 2-(amino ethyl)ethanol amine (AEEA); Cyclic amine–Piperazine; Poly amine–N-(2-aminoethyl)-1, 3-propane diamine). It was observed that polyamines and cyclic amines are having higher reaction rate than primary, and secondary amines. Therefore, the kinetics of the reaction of carbon dioxide with six cyclic amines)) in aqueous solutions has been studied at (298.15 to 313.15) K over a concentration range of (20to120) mol⋅m−3 using the stopped-flow technique.(Piperazine (PZ),1-methyl piperazine (1-MPZ),2-methyl piperazine (2-MPZ),1-ethyl piperazine (1-EPZ),N-(2-hydroxyethyl) piperazine (1-HEPZ) and 3-morpholino propyl amine (3-MOPA). PZ has the highest reaction rate and 1-MPZ has the lowest. The trend of reaction rates are given as (PZ>2-MPZ>1-EPZ>3-MOPA>HEPZ>1-MPZ). All the studied cyclic amines were found to have fractional reaction order with respect to amine varying from 0.9 to 2.43.Termolecular mechanism and Zwitterion-mechanism were used for calculating the rate parameters by fitting the experimental data. [Copyright &y& Elsevier]

Abstract: One-pot three-component Kabachnik–Fields synthesis of α-aminophosphonates with high yields from the reaction between carbonyl compound, primary amine, and substituted phosphite can be carried out in a short period, using H-beta zeolite as a reusable catalyst. [ABSTRACT FROM AUTHOR]

Abstract: Primary amines catalyzed the asymmetric Michael addition of ethyl 2-fluoro-2-nitroacetate to enones to provide chiral α-fluoro-α-nitro ester ketones with two contiguous stereogenic centers, one of which is a fluorinated quaternary chiral center, with excellent enantioselectivities and in moderate to good yields. [Copyright &y& Elsevier]

A series of Cinchona alkaloids derived organocatalysts have been developed and evaluated in the direct asymmetric intermolecular aldol reaction of 4-nitrobenzaldehyde and cyclohexanone. The catalyzed reactions of various aldehydes and ketones gave the corresponding aldol products with moderate to high enantioselectivities (up to 92%) and diastereoselectivities (up to >99/1, anti/syn) in the presence of 3e in brine. Graphical Abstract: [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

An efficient one-pot synthesis of tetrahydro-2,5-dioxofuran-3-yl alkylcarbamodithioates via three-component reaction of maleic anhydride, CS2, and primary amines in good yields is described. [ABSTRACT FROM AUTHOR]

Abstract: The LBAs (Lewis acid-assisted Brønsted acid catalysis) is proposed as possible mechanistic process in the simple FeCl3-catalyzed Michael reactions of chalcones with active methylene compounds in organic solvents. And iron salts were found to be effective promoters in the asymmetric Michael addition of 4-hydroxycoumarin to α,β-unsaturated ketone, which resulted in excellent yield and high level of enantioselectivity (up to 91% ee) in the presence of low catalytic amount of iron and simple chiral primary amine. [Copyright &y& Elsevier]

The amination of the Baylis-Hillman acetates with primary amines can be dramatically promoted with improved yields and shortened reaction time under ultrasound irradiation. The selected aromatic, heteroaromatic, and aliphatic amines were investigated as the effective candidates for the sonochemical transformation. [ABSTRACT FROM AUTHOR]

Some novel 4,5-disubstituted-2,4-dihydro-3H-1,2,4-triazol-3-one (3, 6, 8, 9) derivatives and or 3-(4-methylphenyl)[1,2,4]triazolo[3,4-b][1,3]benzoxazole (5) were synthesized from the reaction of various ester ethoxycarbonylhydrazones (1a-e) with several primary amines. The synthesis of 4-amino-5-(4-chlorophenyl)-2-[(5-mercapto- 1,3,4-oxadiazol-2-yl)methyl]-2,4-dihydro-3H-1,2,4-triazol-3-one (13) was performed starting from 4-Amino-5-(4-chlorophenyl)-2,4-dihydro-3H-1,2,4-triazol-3-one (2) by four steps; then 13 was converted to the corresponding Schiff base (14) by using 4- methoxybenzaldehyde. Finally, two Mannich base derivatives of 14 were obtained by using morpholine or methyl piperazine as amine component. All newly synthesized compounds were screened for their antimicrobial activities and some of which were found to possess good or moderate activities against the test microorganisms. [ABSTRACT FROM AUTHOR]

Abstract: A mild and efficient method has been developed using ultrasound irradiation for the synthesis of imidazolium and pyridinium salts based on the Zincke reaction. Tertiary nitrogen nucleophiles such as pyridines and imidazoles can be alkylated with primary amine by simply using their ammonium form Zincke salts. In almost all cases, a clear yield increase results and a dramatic reduction of the reaction time accompanied by an improved quality of the products occurs. [Copyright &y& Elsevier]

Abstract: Electrochemical oxidation of primary amine in ionic liquid media has been investigated. The ionic liquid chosen for this study was 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide. Two primary amine compounds are used for this study; 4-nitrobenzylamine and 2-aminoethylferrocenylmethylether. The oxidation of the amino compounds in ionic liquid conduces to the modification of the electrode surface. The modified electrodes were characterized by cyclic voltammetry and XPS analysis. Both techniques support the presence of an organic layer strongly attached onto the electrode surface. The surface concentration of the attached group obtained in this media was found to be around 1 to 3×10−10 molcm−2. The use of ionic liquid as media for the grafting leads to decrease of the surface concentration of the grafted layer; and the formation of less dense layer compared with classical solvent such as acetonitrile. [Copyright &y& Elsevier]

Abstract: Rh/Mo catalysts formed in situ from Rh6(CO)16 and Mo(CO)6 are effective for the liquid phase hydrogenation of CyCONH2 to CyCH2NH2 in up to 87% selectivity, without the requirement for ammonia to inhibit secondary amine formation. Use of in situ HP-FTIR spectroscopy has shown that decomposition of metal carbonyl precursors occurs during an extended induction period, with the generation of recyclable, heterogeneous, bimetallic catalysts. Variations in Mo:Rh content have revealed significant synergistic effects on catalysis, with optimum performance at values of ca. 0.6, and substantially reduced selectivities at ⩾1. Good amide conversions are noted within the reaction condition regimes 50–100bar H2 and 130–160°C. Ex situ characterization of the catalysts, using XRD, XPS and EDX-STEM, has provided evidence for intimately mixed (ca. 2–4nm) particles that contain metallic Rh and reduced Mo oxides, together with MoO3. Silica-supported Rh/Mo analogues, although active, perform poorly at <150°C and deactivate during recycle. [Copyright &y& Elsevier]

Abstract: Selectively extracting tungsten to purify sodium molybdate solution was studied using primary amine N1923, including various conditions, such as equilibrium pH values, concentrations of extractant in organic phase and metals in feed solution, contact time of extraction and stripping, types of acidic solutions added, temperature of extraction and the dosage of stripping agent. Graphical method using McCabe-Thiele diagram and counter-current extraction simulation (CCES) were used to determine the required stages of deep removal of tungsten. The results show that appropriate concentrations of tungsten and molybdenum in feed solution have great influence on the difficult degree of the separation between the two metals. Organic phase including 0.051M of N1923 modified by LK-N21X diluted in kerosene can extract 92.7% of tungsten in sulfuric acid solution at equilibrium pH value of 7.07 for 10min in one-stage extraction at 15.5°C, and the separation factor reaches 329 under those optimum conditions. A two-stage CCES removes 99.83% of tungsten and obtains the purified sodium molybdate solution where W/Mo (mass ratio) reaches 2.9×10−5. Stripping can be accomplished by NaOH solution completely and quickly. Furthermore, the extraction and stripping reactions of tungsten and molybdenum in equilibrium were proposed. [Copyright &y& Elsevier]

A simple primary-tertiary diamine has been explored as a novel catalyst for the Morita-Baylis- Hillman reaction of MVK and aryl aldehydes, and moderate to good chemical yields were obtained. Detailed mechanism study indicated that the diamine acted as a bifunctional cooperation catalyst via a bicyclic enamino-quaternary ammonium intermediate. [ABSTRACT FROM AUTHOR]

Abstract: It is surveyed that the amination of the Baylis–Hillman acetates with primary amines can be dramatically promoted in improved yields and shortened reaction time under ultrasound irradiation than those under conventional stirring. The extensive scope of both amines and acetates are screened to investigate the relationship between substituents and their performance in such transformation. [Copyright &y& Elsevier]

The hydrogenation of propionitrile on copper-lanthanide oxide catalysts (2Cu·CeO2 and 4Cu·Ln2O3 (Ln = La, Pr, Nd)) was studied in the gas phase. The activity of the catalysts varies with the lanthanide in the order 2Cu·CeO2 > 4Cu·Pr2O3 > 4Cu·La2O3 ≥ 4Cu·Nd2O3, while the activation energies varies in the opposite order, except for 2Cu·CeO2. The main product was the primary amine, n-propylamine. The formation of the unstable imine CH3CH2N=CHCH3 as a major product over 2Cu·CeO2 seems to be consistent with the acidity of the catalyst. The catalysts were more selective than conventional copper impregnation catalysts, Cu (10 wt.%) on SiO2, La2O3 or CeO2, that produce significant quantities of the secondary amine. [Copyright &y& Elsevier]

Cs2CO3-catalyzed transamination of primary amines and ethylene carbonate proceeds to form 1,3-disubstituted symmetrical/unsymmetrical ureas in excellent yields. The effect of different reaction parameters such as influences of bases, temperature, and reaction time were investigated for the title reaction. [ABSTRACT FROM AUTHOR]

Abstract: Monodisperse titania spheres with particle diameters in the range 380–960nm were successfully synthesized by hydrolysis and condensation of titanium tetraisopropoxide. The preparation was performed using ammonia or dodecylamine (DDA) as a catalyst in methanol/acetonitrile co-solvent at room temperature. The samples were characterized by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, dynamic light scattering, and nitrogen sorption measurement. The use of DDA was effective for the synthesis of monodisperse titania spheres with low coefficient of variation. When the titania spherical particles with coefficient of variation less than 4% were obtained, the colloidal crystallization easily occurred simply by centrifugation. The monodispersity was maintained even after crystallization of the particles by high temperature annealing. The titania particles prepared using DDA had mesopores near the surface of the spheres, providing high pore accessibility to the sphere from the surface–air interface. The particle size uniformity and photocatalytic reactivity of the titania prepared using DDA were higher than those of the titania prepared using ammonia. [Copyright &y& Elsevier]

Abstract: The potential of recovering propionic acid from discharged water in vitamin B12 production by anaerobic fermentation was investigated in this paper. A primary amine, N1923, was used as the extractant, kerosene as diluter and n-octanol as modifier. The influences of the content of N1923 in the organic phase, the phase ratio and the pH of aqueous phase on the extraction yield of propionic acid were studied. The organic phase composition with the volume ratio was proposed of N1923:kerosene:n-octanol as 45:35:20. Under conditions of the phase ratio (o/w) as 1:4, the pH of aqueous phase of 3.0 and after 5min extraction, the extraction yield of propionic acid can be over 97%. [Copyright &y& Elsevier]

The direct asymmetric aldol reaction catalyzed by the simple and commercially available chiral primary diamines, (1S,2S)-1,2-diphenylethane-1,2-diamine and (1R,2R)-1,2-diphenylethane-1,2-diamine, is presented. The catalyst system is a primary amine with Brønsted acid-catalyzed direct aldol reaction of p-nitrobenzaldehyde and cyclohexanone with high chemo- and stereoselectivity on water, which furnishes the corresponding β-hydroxyketone with up to 94% ee. [ABSTRACT FROM AUTHOR]

• Nitriles are the main products from the reaction between ferrate and primary amines. • Minor products include aldehydes and carboxylic acids. • Buffering conditions impact the reaction between ferrate and primary amines. • Non-halogenated nitriles have low cytotoxicity and low oxidative stress response. • The formation of nitriles is preferable to the formation of nitroalkanes. Ferrate (Fe(VI)), a promising water treatment oxidant, can be used for micropollutant abatement or disinfection byproduct mitigation. However, knowledge gaps remain concerning the interaction between Fe(VI) and dissolved organic matter structures, notably primary amines. This study investigated degradation kinetics and products of several aliphatic primary amines by Fe(VI). Primary amines showed appreciable reactivity toward Fe(VI) (2.7–68 M−1s−1 at pH 7–9), ranking as follows: benzylamine > phenethylamine > phenylpropylamine > methylamine ≈ propylamine. Nitriles were the main oxidation products of the primary amines, with molar yields of 61–103%. Minor products included aldehydes, carboxylic acids, nitroalkanes, nitrite, nitrate, and ammonia. The buffering conditions were important. Compared to phosphate, borate enhanced the reactivity of the amines and shifted the products from nitriles to carbonyls. An evaluation of the effect potency of some cyano-compounds by an in vitro bioassay for oxidative stress response and cytotoxicity suggested that non-halogenated nitriles are unlikely to pose a significant threat because they were only toxic at high concentrations, acted as baseline toxicants and did not cause oxidative stress, unlike halonitroalkanes or halonitriles. The formation of non-halogenated nitriles is preferable to the formation of nitroalkanes arising from the ozonation of primary amines (other than amino acid N-terminals) because, during chlorination, nitriles remain unreactive while nitroalkanes lead to potent halonitroalkanes. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: The kinetics of the reactions of the primary and secondary amine groups in aqueous DETA solution were measured in a string of discs contactor at different concentrations and temperatures. The reaction rates of the primary amine group were performed at very low loading and for the secondary amine group H2SO4 was used to neutralize the primary amine groups. The reaction rates increase with increasing DETA concentration and temperature. The reaction order is found to be a broken-order and to vary slightly with the temperature. Both the termolecular and the zwitterion mechanisms were applied to interpret the experimental data and gave identical result. Both DETA and water contribute to the carbamate formation in the primary and secondary amine groups. The rate of CO2 absorbed in the primary amine group is faster than the secondary amine group and about 100 times higher. [Copyright &y& Elsevier]

• Formation of four amines and ethers H-bonded complexes is established through acoustic method. • UV-Vis. Spectral data support the existence of such complexes in n-hexane. • Thermodynamic parameters K, ΔG, ΔH and ΔS obtained by acoustical and optical methods are reported. • ΔG values reveal thermodynamic stability and ΔH data show exothermic nature of complexes. • Structure of amine and ether influences the formation of these complexes. The present work deals with experimental determination of acoustical parameters to investigate the influence of structure of amines and ethers on thermodynamic properties of four hydrogen bonded complexes in n-hexane solvent at four different temperatures in the range 294.15 K-310.15 K. Benzyl amine (BA) and n-propyl amine (NPA) are used as H-donors while anisole (ANI) and diphenyl ether (DPE) act as H-acceptors. The existence of these H-bonded complexes in solution is also supported by UV spectral data. The formation constants (K) of the complexes determined by ultrasonic and UV-Vis. spectral methods at 303.15 K are comparable. Further, it is observed that the interactions in the aliphatic amine - aromatic ether systems are stronger than aralkyl amine (BA) – ether systems. The thermodynamic parameters confirm that all the four complexes are thermodynamically stable and formation of these complexes is exothermic. The sign of ΔS shows there are strong intermolecular interactions between amines and ethers in n-hexane medium. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: We have developed a new strategy to improve the stereoselectivity in enamine catalysis by the introduction of super-hydrophobic long-chain silicone/polysiloxane as support/functional group for a model aldol reaction. The homogeneous direct aldol reaction of cyclic ketones with different aromatic aldehydes catalyzed by polysiloxane-derived primary amines has been reported with high yields, good diastereoselectivity, and up to 99% ee. [Copyright &y& Elsevier]

Abstract: Noyori’s Ts-DPEN ligand bearing an amino sulfonamide moiety and with a primary amino group on a chiral scaffold was found to be a simple and efficient bifunctional organocatalyst for the asymmetric Michael addition of 1,3-dicarbonyl compounds to nitroolefins, which gave highly functional Michael adduct with quaternary stereocenters in good enantioselectivities (up to 84%ee) and dr (up to 5.7:1 dr). [Copyright &y& Elsevier]