Formation Of Primary Amines Research Articles

Analysis of thermodynamics, kinetics, and reaction pathways in the amination of secondary alcohols over Ru/SiO2

This work considers the Ru-mediated amination of secondary alcohols with ammonia in vapor and liquid media. We map thermodynamic constraints, and we probe the impacts of species partial pressure, residence time, and reaction temperature on rate, selectivity, and catalyst stability. Alcohol amination consumes no H2, and H2 has no significant impact on amination kinetics; however, operating under H2 benefits Ru stability. Primary amine selectivity increases with ammonia pressure and alcohol conversion, and the latter observation is consistent with the formation of primary amines through a network of sequential reactions. Unfortunately, primary amines are susceptible to secondary deamination to form hydrocarbons. As is typical of processes that seek to isolate a reactive intermediate, the main selectivity challenge here is identifying residence times that are long enough to accumulate high substrate conversion but short enough to avoid secondary deamination. In general, moderate residence times will maximize the production of primary amines. Insights extend across a broad substrate scope, and we observe 70 – 90% yield of primary amines from linear, cyclic, and heterocyclic alcohols. That said, heterocyclic alcohols appear susceptible to product inhibition, so achieving high conversions requires longer residence times and/or increased ammonia pressures.

Synthesis of primary amines via linkage of hydroaminomethylation of olefins and splitting of secondary amines

An elegant method capable of synthesising primary amines from olefins is presented by a new orthogonal tandem amination reaction. Rh/Ru-catalysed bis-hydroaminomethylation of dienes towards secondary amines 10 and primary amines 13 is implemented. The obtained secondary amines 10 intermediates are then converted in a second reaction step to primary amines 13via splitting of amines through subsequent addition of ammonia. Influences on the orthogonal catalytic system towards the formation of primary amines are discussed and point towards a novel N-dealkylation and alkylation mechanism. For the model substrate dicyclopentadiene (tricyclo[5.2.1.02,6]deca-3,8-diene, dcpd 1) yields of up to 29% of the primary diamine (3(4),8(9)-bis(aminomethyl)tricycle-[5.2.1.02,6]decane, TCD-diamine 13) were achieved under optimized conditions, with a primary amine 13 to secondary amine 10 ratio of 5.8. The reverse reaction towards secondary amines was revealed as the limiting factor in the selective reaction towards primary amines 13 caused by the equilibrium of the reaction. In this equilibrium, however, a slight tendency towards the primary amine 13 was identified.

Efficiency, Selectivity and Reusability of CuFe<sub>2</sub>O<sub>4</sub> Nanoferrite Particles for Reductive Transformation of P-Nitrophenol to P-Aminophenol

MFe2O4(Where M = Cu2+, Co2+and Ni2+) has been synthesized using a citrate sol-gel self-ignition process in order to investigate their catalytic performance for reduction of p-nitrophenol. The ignited precursors were annealed at 400, 600, 800 and 1000°C for 2 hrs. to obtain nanoferrite particles. The prepared samples were characterized using various instrumental techniques like FT-IR, XRD, and UV-VIS. X-ray analysis confirms the formation of single phase. Powder X-Ray diffraction patterns showed the formation of body centered tetragonal structure for CuFe2O4and cubic structure for CoFe2O4and NiFe2O4. It was observed that as the annealing temperature increases from 400 to 1000°C, the XRD peaks grow sharper attributing to an increase in particle size with increasing temperature; which is consistent with TEM. Transmission Electron micrographs analysis revealed an enhancement in grain size with the annealing temperature. The disappearance of yellow colour indicated the conversion of p-nitrophenol to p-aminophenol and the occurrence of colour disappearance has been observed in one minute using CuFe2O4(8mol %). This suggested the efficiency of CuFe2O4in catalyzing p-nitrophenol reduction. FT-IR and UV-Visible spectroscopy has been used to confirm this reduction process. FT-IR spectra showed N-H stretching vibrations at ~3365 cm-1and 3350 cm-1attributing to the formation of primary amine using CuFe2O4for catalyzing reduction of p-nitrophenol. The disappearance of the absorption band at 400 nm in the UV-Visible spectrum also confirms the conversion of p-nitrophenol to p-aminophenol.

Biodegradation of Bloodmeal-Based Thermoplastics in Green-Waste Composting

Polymers that are compostable and manufactured from renewable resources have gained significant importance in recent years. The objective of this work was to assess the biodegradability of bloodmeal-based thermoplastics in a commercial green-waste composting situation. Materials plasticised with tri-ethylene–glycol lost about 45% of their original mass after 12 weeks composting while unplasticised samples lost 35%. Degradation appeared to have been in two phases; an initial loss of soluble, low molecular compounds in the mesophilic phase followed by degradation of high molecular compounds as the temperature exceeded about 40 °C in the thermophilic phase. It was found that as degradation proceeded materials became more soluble. In addition, plasticised and unplasticized samples contained about 60 wt% moisture after 4 weeks of composting conditioning at 50% relative humidity resulted in approximately 8–10 wt% moisture, unaffected by the extent of degradation. FTIR revealed that proteins underwent hydrolytic cleavage resulting in the formation of primary amines. A significant reduction in combustion temperature was observed, indicative of a reduction in covalent bonding, likely due to shorter chains lengths or less cross-linking.

ChemInform Abstract: Borylnitrenes: Electrophilic Reactive Intermediates with High Reactivity Towards C—H Bonds.

AbstractReview: 109 refs.

Borylnitrenes: electrophilic reactive intermediates with high reactivity towards C–H bonds

Borylnitrenes (catBN 3a and pinBN 3b; cat = catecholato, pin = pinacolato) are reactive intermediates that show high tendency towards insertion into the C-H bonds of unactivated hydrocarbons. The present article summarizes the matrix isolation investigations that were aimed at identifying, characterizing and investigating the chemical behaviour of 3a by spectroscopic means, and of the experiments in solution and in the gas phase that were performed with 3b. Comparison with the reactivity reported for difluorovinylidene 1a in solid argon indicates that 3a shows by and large similar reactivity, but only after photochemical excitation. The derivative 3b inserts into the C-H bonds of hydrocarbon solvents in high yields and thus allows the formation of primary amines, secondary amines, or amides from "unreactive" hydrocarbons. It can also be used for generation of methylamine or methylamide from methane in the gas phase at room temperature. Remaining challenges in the chemistry of borylnitrenes are briefly summarized.

Total Synthesis Without Protecting Groups: Pyrrolidines and Cyclic Carbamates

A protecting group free synthesis of 2,3-cis substituted hydroxypyrrolidines is reported. Two novel reaction methodologies allow for the stereoselective formation of cyclic carbamates from olefinic amines, and the formation of primary amines via a Vasella/reductive amination reaction, both performed in aqueous media.

Denitrocyclization in synthesis of dibenzo[b,f][1,4]thiazepin‐11(10h)‐ones and their derivatives

Abstractmagnified imageA convenient synthesis of the novel dibenzo[b,f][1,4]thiazepin‐11(10H)‐ones is reported. As a key step, the synthetic route includes intramolecular aromatic denitrocyclization of 2‐(2,4‐dinitro‐phenylsulfanyl)‐benzoic acid amides. Efficient procedures for denitrocyclization in the presence of different bases are developed. Reduction of the nitro group in the obtained heterocycles resulted in formation of primary amines, which were transformed into amides by acylation with different carboxylic acids. The synthesized compounds have a great potential of bioactivity and are useful objects for biomedicinal screening.

Formation of Primary Amines on Silicon Nitride Surfaces: a Direct, Plasma-Based Pathway to Functionalization

Silicon nitride is the most commonly used passivation layer in biosensor applications where electronic components must be interfaced with ionic solutions. Unfortunately, the predominant method for functionalizing silicon nitride surfaces, silane chemistry, suffers from a lack of reproducibility. As an alternative, we have developed a silane-free pathway that allows for the direct functionalization of silicon nitride through the creation of primary amines formed by exposure to a radio frequency glow discharge plasma fed with humidified air. The aminated surfaces can then be further functionalized by a variety of methods; here we demonstrate using glutaraldehyde as a bifunctional linker to attach a robust NeutrAvidin (NA) protein layer. Optimal amine formation, based on plasma exposure time, was determined by labeling treated surfaces with an amine-specific fluorinated probe and characterizing the coverage using X-ray photoelectron spectroscopy (XPS). XPS and radiolabeling studies also reveal that plasma-modified surfaces, as compared with silane-modified surfaces, result in similar NA surface coverage, but notably better reproducibility.

Carbon-sulfur bond cleavage in Bis(N-alkyldithiocarbamato)cadmium(II) complexes: heterolytic desulfurization coupled to topochemical proton transfer.

Three bis(N-alkyldithiocarbamato)cadmium(II) complexes [Cd(S(2)CNHR)(2)] (1, R = n-C(3)H(7); 2, R = n-C(5)H(11); 3, n-C(12)H(25)) were prepared by metathesis of the corresponding lithium salt, Li[S(2)CNHR], with cadmium chloride. The crystal structures of 2 and 3 consist of planar molecular units of [Cd(S(2)CNHR)(2)] connected by intermolecular Cd.S interactions to give a one-dimensional chain. The chains are connected by a network of intermolecular N-H.S hydrogen bonds between the dithiocarbamato nitrogen atom and bridging sulfur atoms in neighboring chains. In solution, the (113)Cd NMR spectrum of 2 is dependent on concentration and temperature, indicative of a dimerization equilibrium mediated by similar Cd.S intermolecular bridging interactions. In the solid state, thermal gravimetric analyses show that all three complexes decompose smoothly via a heterolytic C-S bond cleavage reaction to give the corresponding alkyl isothiocyanate and cadmium sulfide as the primary products, with the formation of primary amine and CS(2) as coproducts. These products can result only from the net transfer of protons between N-alkyldithiocarbamato ligands in the solid state. Thus, the C-S bond cleavage reaction is interpreted in terms of the topochemical arrangement of molecular units in the crystalline state, which provides a pathway for proton transfer between ligands via N-H.S hydrogen bonds. Decomposition was also initiated by addition of a tertiary amine to a solution of [Cd(S(2)CNHR)(2)]. This confirms that C-S bond cleavage must be coupled to deprotonation of the -NH group, and explains why dialkylated derivatives [Cd(S(2)CNR(2))(2)] are inert to this particular mode of C-S bond cleavage. This system thus constitutes an unusual example of heterolytic, nonoxidative C-S bond cleavage that appears to proceed by a topochemical transfer of protons, which has implications for C-S bond cleavage processes in single-source precursors for II-VI semiconductor materials.

The effect of catalyst pore structure on liquid phase catalysis: Hydrogenation of stearonitrile over ruthenium supported on mesoporous sulfated zirconia

Ruthenium supported on mesoporous sulfated zirconia was tested as a catalyst for the liquid phase hydrogenation of stearonitrile, >n-C 17H 35CN, and compared with Ru, supported on either microporous sulfated zirconia or the zeolite HY. The mesoporous catalyst is significantly more active than the microporous catalyst; the zeolite supported catalyst is inactive under the same conditions. The results illustrate the effect of pore size on the reaction rate for large molecules. Both mesoporous and microporous catalysts show good stability and a high selectivity towards formation of primary amine. The reaction order in hydrogen is positive with both catalysts; the apparent reaction order in nitrile is negative with the mesoporous catalyst but positive with the microporous catalyst. The activation energy of the reaction is about 90 kJ/mol. TPR data show that under the conditions chosen for pretreatment no SO 4 reduction takes place; at higher temperature the sulfur is reduced from S 6+ to S 2−.

Mechanistic study of thermal behaviour and combustion performance of epoxy resins. II. TGDDM/DDS system

The kinetics of curing of tetraglycidyl 4,4′-diaminodiphenylmethane (TGDDM) with 50% or 85% of stoichiometric 4,4′-diaminodiphenylsulfone (DDS) was studied by differential scanning calorimetry. It was found that the activation energy of the process increases with advancement of curing, which is caused by concomitant homopolymerisation of TGDDM accompanied by cyclisation. The structure of the cured formulations was characterised by infrared and 13C NMR spectroscopy. The mechanistic study of thermal decomposition of TGDDM/DDS systems was carried out by thermogravimetry and differential scanning calorimetry in inert atmosphere and by thermal volatilisation analysis in vacuo. It was found that above 200 °C elimination of water from secondary alcohol groups takes place with formation of aliphatic unsaturation. Breaking of the resulting weakened allylic CN bonds leads to chain scission with formation of primary amine and quinolin-type chain ends. Scission of non-allylic CN bonds followed by evolution of acetone was observed at about 300 °C. The volatilisation of sulfur-containing species and formation of a thermostable char occurred on further heating to 400 °C. The poorer fire resistance of TGDDM/DDS formulations in comparison with homopolymerised TGDDM is discussed on the basis of a lower yield of char and a higher yield of gases.

Ultraviolet Photolysis and Ortho-Phthalaldehyde-Mercaptoethanol Derivatization of Pharmaceuticals for Enhanced Fluorescence Detection in HPLC

Abstract Several classes of nitrogenous pharmaceutical were examined for fluorescence after ultraviolet (UV) radiation induced photolysis followed by reaction with o-phthalaldehyde-2-mercaptoethanol (OPA-MERC), and after UV photolysis alone. Photolyses were examined in water, mixtures of methanol/water (1:1), and acetonitrile/water (1:1). Acetone was assessed as a photosensitizer to enhance photolysis and fluorescence response. Flow injection analysis and high-performance liquid chromatographic techniques were used for several pharmaceuticals. The analytes were subjected to UV photolysis and reaction with OPA-MERC reagent for generation of fluorophores that responded to fluorescence detection. During photolysis, solvent type as well as the presence of photosensitizers seem to play a significant role in the formation of primary amines and fluorophores. Photochemical transformation products of some of the pharmaceutical chemicals are proposed. Analytical figures of merit were determined for some analytes. T...

Sodium aluminum hydride reduction of organic compounds in hydrocarbon media

The reduction of complex esters and carbonyl compounds in hydrocarbon media by aluminum hydrides of the alkali metals results in the formation of the corresponding alcohol in high yield. The reduction of nitriles proceeds with the formation of primary amines.