Tertiary Alkylamines Research Articles

Design of highly efficient adsorbents for removal of gaseous methyl iodide using tertiary amine-impregnated activated carbon: Integrated experimental and first-principles approach

Activated carbons (ACs) impregnated with triethylenediamine (TEDA) and quinuclidine (QD) are prepared for the removal of methyl iodide (CH3I) gas in the event of nuclear accidents. The effect of the tertiary amine loading (1, 5, and 10 wt.%) on the adsorption capability of the ACs is evaluated under dry and humid (RH 75%) conditions. Experimental evaluation of the 'breakthrough' combined with rigorous first-principles calculations enables us to identify the fundamental mechanism underlying the superior adsorption capability of QD to TEDA for real application, especially under humid conditions. The adsorption of CH3I by the impregnated ACs under dry conditions strongly depends on the physical properties (porosity) of the adsorbent. On the other hand, the chemical properties and the tertiary amine loading play dominant roles in CH3I adsorption at 75% RH. In particular, this study suggests a novel mechanism of the protonation reaction, rather than the already known alkylation of tertiary amines, to capture CH3I chemically under humid conditions. The molecular-level behavior of amines and water is a key factor for the enhanced adsorption of methyl iodide. The adsorbents developed herein can be applied to the efficient removal of radioactive methyl iodide in severe accidents.

Iodinated Polystyrene for Polymeric Charge Transfer Complexes: Toward High-Performance Near-UV and Visible Light Macrophotoinitiators

In recent works, charge transfer complexes (CTCs) have proved to be useful photoinitiating agents to trigger free radical polymerization. However, because of their low molecular weights, migration issues remain very important. In line with pressing migration concerns around photoinitiating systems (e.g., in 3D polymer networks), we report here the use of the first polymeric CTC based on iodinated polystyrene/amine interactions. This study shows the formation of the CTC between the polystyrene derivative (electron acceptor EA) and a tertiary alkylamine (electron donor ED); the ability of this EA/ED couple in a CTC to act as a photoinitiator for the polymerization of multifunctional acrylates upon LED@405 nm irradiation is investigated. Examples of applications to 3D-resolved laser write of thick controlled samples (1 mm) are provided.

Investigation of factors influencing the separation of diastereomers of phosphorothioated oligonucleotides

This study presents a systematic investigation of factors influencing the chromatographic separation of diastereomers of phosphorothioated pentameric oligonucleotides as model solutes. Separation was carried out under ion-pairing conditions using an XBridge C18 column. For oligonucleotides with a single sulfur substitution, the diastereomer selectivity was found to increase with decreasing carbon chain length of the tertiary alkylamine used as an ion-pair reagent. Using an ion-pair reagent with high selectivity for diastereomers, triethylammonium, it was found the selectivity increased with decreased ion-pair concentration and shallower gradient slope. Selectivity was also demonstrated to be dependent on the position of the modified linkage. Substitutions at the center of the pentamer resulted in higher diastereomer selectivity compared to substitutions at either end. For mono-substituted oligonucleotides, the retention order and stereo configuration were consistently found to be correlated, with Rp followed by Sp, regardless of which linkage was modified. The type of nucleobase greatly affects the observed selectivity. A pentamer of cytosine has about twice the diastereomer selectivity of that of thymine. When investigating the retention of various oligonucleotides eluted using tributylammonium as the ion-pairing reagent, no diastereomer selectivity could be observed. However, retention was found to be dependent on both the degree and position of sulfur substitution as well as on the nucleobase. When analyzing fractions collected in the front and tail of overloaded injections, a significant difference was found in the ratio between Rp and Sp diastereomers, indicating that the peak broadening observed when using tributylammonium could be explained by partial diastereomer separation.

Alkyl halide/tertiary amine as novel initiators for free radical polymerizations of methyl methacrylate, methyl acrylate and styrene

A series of combinations of alkyl halide with tertiary amine such as ethyl α-bromophenylacetate/tris[2-(dimethylamino)ethyl)]amine (αEBP/Me6TREN), ethyl 2-bromoisobutyrate/triethylamine (EBiB/TEA), and ethyl 2-chloropropionate/N,N,N′,N′,N′′-pentamethyldiethylenetriamine (ECP/PMDETA) have been developed as novel free radical initiators and used for the polymerizations of methyl acrylate (MA), methyl methacrylate (MMA) and styrene (St). The effects of the structure of alkyl halide and tertiary amine on the polymerization of MA were investigated. Gel permeation chromatograph (GPC) and proton nuclear magnetic resonance (1H NMR) have been utilized to analyze the end group of the obtained poly(methyl acrylate). Electron spin resonance (ESR) spectroscopy was employed to identify the structure of the radicals produced by αEBP/Me6TREN, and the results indicated that αEBP reacted with Me6TREN via a single electron transfer (SET) nucleophilic mechanism to produce corresponding ethyl α-phenylacetate radicals which subsequently initiated the polymerization of MA. As both alkyl halide and tertiary amine are commercially available at low cost, non-explosive, and ease of use and storage in comparison with conventional azo, peroxide or persulfate initiators, the combination of alkyl halide and tertiary amine as a free radical initiator is promising for large-scale practical applications.

A novel supported quaternary NiCuMgFe/Al2O3 catalyst for the synthesis of alkyl tertiary amines

The catalytic amination of aliphatic alcohols to manufacture alkyl tertiary amines is a promising process. In this paper, novel types of quaternary NiCuMgFe/Al2O3 and NiCuZnFe/Al2O3 catalysts were prepared via co-precipitation method and the performances were contrasted in details. With the optimum molar ratio nNi:nCu:nMg:nFe = 1.25:1:0.3:0.6, NiCuMgFe/Al2O3 catalyst delivered a N-propyldioctylamine (NPDA) yield of 94.3% and good recycling stability. In addition, NiCuMgFe/Al2O3 catalyst displayed the universality for several other types of alkyl tertiary amines. The characterizations of XRD, Raman, UV–vis-DR, XPS and H2-TPR revealed that obvious synergistic effect between the promoters Mg and Fe occurred, and they significantly improved both the percentage of Cu0 species and the dispersion of NiO active sites. As a result, the hydrogenation and dehydrogenation abilities of NiCuMgFe/Al2O3 catalyst were balanced towards a high conversion of alcohol and a high selectivity to tertiary amines.

Multicomponent synthesis of tertiary alkylamines by photocatalytic olefin-hydroaminoalkylation.

There is evidence to suggest that increasing the level of saturation (that is, the number of sp3-hybridized carbon atoms) of small molecules can increase their likelihood of success in the drugdiscovery pipeline1. Owing to their favourable physical properties, alkylamines have become ubiquitous among pharmaceutical agents, small-molecule biological probes and pre-clinical candidates2. Despite their importance, the synthesis of amines is still dominated by two methods: N-alkylation and carbonyl reductive amination3. Therefore, the increasing demand for saturated polar molecules in drug discovery has continued to drive the development of practical catalytic methods for the synthesis of complex alkylamines4-7. In particular, processes that transform accessible feedstocks into sp3-rich architectures provide a strategic advantage in the synthesis of complex alkylamines. Here we report a multicomponent, reductive photocatalytic technology that combines readily available dialkylamines, carbonyls and alkenes to build architecturally complex and functionally diverse tertiary alkylamines in a single step. This olefin-hydroaminoalkylation process involves a visible-light-mediated reduction of in-situ-generated iminium ions to selectively furnish previously inaccessible alkyl-substituted α-amino radicals, which subsequently react with alkenes to form C(sp3)-C(sp3) bonds. The operationally straightforward reaction exhibits broad functional-group tolerance, facilitates the synthesis of drug-like amines that are not readily accessible by other methods and is amenable to late-stage functionalization applications, making it of interest in areas such as pharmaceutical and agrochemical research.

Influence of Cation Size on the Structural Features and Interactions in Tertiary Alkylammonium Trifluoroacetates: A Density Functional Theory Investigation.

We present the results of electronic structure calculations based on density functional theory (DFT) in order to investigate the reactions of the interaction of tertiary alkylamines with alkyl groups of different sizes (triethyl, tributyl, dimethylethyl, and diisopropylethyl) with trifluoroacetic acid. We have obtained data on the affinity of the studied amines with a proton. It has been shown that amine interaction with the acid leads to proton transfer from the acid to the amine and formation of ions held together in the ion pair by electrostatic interaction and a very strong hydrogen bond. We have also investigated the energy profiles of the proton transfer from the tertiary alkylammonium cation to the trifluoroacetate anion within the ion pair and found different correlations between the geometric characteristics of the H-bond and the parameters obtained by the natural bond orbitals and quantum theory of atoms in molecules analyses. It has been established that the interionic interactions in these systems weaken as the length and the degree of cation alkyl chain branching increase. A good qualitative agreement between the theoretical results and the experimental data on physicochemical properties has been obtained.

Determination of atmospheric alkylamines by ion chromatography using 18-crown-6 as mobile phase additive

An improved ion chromatographic method including two elution procedures was proposed for the quantitative determination of atmospheric alkylamines in field atmospheric samples involving high levels of inorganic cations by using 18-crown-6 as mobile phase additive. When 18-crown-6 was added to the mobile phase, the retention times increased significantly for Na+, NH4+, K+ and primary alkylamines but decreased for secondary and tertiary alkylamines due to the complexation with certain cations and interaction with both stationary and mobile phases of 18-crown-6. As a result, the separation of the cations was greatly promoted, which reduced the interference of peak distortion of overloaded inorganic cations on the quantitation of adjacent alkylamines. By using the presented method, five inorganic cations (Na+, NH4+, K+, Mg2+, Ca2+) and six alkylamines (dimethylamine (DMAH+), trimethylamine + diethylamine (TMAH+ + DEAH+), propylamine (MPAH+), triethylamine (TEAH+), ethanolamine (MEOAH+) and triethanolamine (TEOAH+)) were effectively separated and determined, and the relative standard derivations (RSDs) of objective cations were all less than 1% for retention time and 3.1% for peak area (n = 9), respectively. The linearity was excellent for each cation (R2 > 0.993) except for NH4+ and TEOAH+ showing a non-linear response (R2 > 0.998 for theoretical non-linear fitting), and the detection limit of these cations were 0.03–1.19 ng. The proposed method was successfully used in the determination of both alkylamines and inorganic cations in ambient particulate matters and gaseous alkylamines in ceiling duct exhaust. The annual average concentrations of DMAH+, TMAH+ + DEAH+ and TEAH+ were 15.56, 4.35 and 16.00 ng m−3 in PM2.5 over Shanghai in 2013. The concentrations of gaseous DMA and TMA + DEA in ceiling duct exhaust reached a maximum of 940.0 and 112.7 μg m−3, and were positively correlated with the human activity intensity, suggesting that human excreta emissions was a potential important source of atmospheric alkylamines in urban area of Shanghai.

Vapor-Phase Amine Intercalation for the Rational Design of Photonic Nanosheet Sensors

The development of vapor sensors with tunable sensitivity and selectivity is highly desirable because of the manifold applications ranging from air quality monitoring to food control. The design of such sensors remains, however, a great challenge. Here, we address this challenge by intercalating primary and tertiary alkylamines with varying alkyl chain lengths into H3Sb3P2O14 nanosheet-based Fabry-Perot interference sensors. As the sensors are photonic in nature, the different amines can be distinguished based on their intercalation time and optical shift. Since the amines are protonated during intercalation and therefore trapped, this allows us to use amine modification as the basis for creating optical sensors. Intercalation of different amines gradually and widely tunes the sensor’s sensitivity and selectivity to various analytes. This adjustment of sensing properties allows us to construct a sensor array on a single chip, which can distinguish different volatile organic compounds. The color change of ...

Oil-in-Water Emulsions Stabilized by Acylglutamic Acid-Alkylamine Complexes as Noncovalent-Type Double-Chain Amphiphiles.

We have studied the preparation and stabilization mechanism of oil-in-water-type emulsions in the presence of amphiphilic 1:1 stoichiometric complexes of acylglutamic acids (CnGlu) with tertiary alkylamines (CnDMA). Relatively stable emulsions were obtained when C16Glu-C16DMA (or C18Glu-C18DMA), hexadecane, and water were homogenized at 80 °C and then stored at room temperature. The gel-liquid crystal phase transition temperatures (Tc) of C16Glu-C16DMA and C18Glu-C18DMA dispersed in water were determined to be ca. 39 and 53 °C, respectively. This indicates that the complexes form an adsorbed layer at the oil/water interface during the homogenization process above the Tc and then change into a gel during storage at room temperature. The gel phase formed at the oil/water interface prevents the oil droplets from coalescing. In contrast, shorter chain analogues (C10Glu-C10DMA and C12Glu-C12DMA) did not yield stable emulsions because their adsorption layers were not able to prevent coalescence of the oil droplets (i.e., the Tc of these analogues was below the room temperature). We have also demonstrated that the dispersion stability of these emulsion systems can be controlled by changing the aqueous pH.

Counterion-Induced Control of the Colloidal State of Polyamic Acid Nanoparticles for Electrophoretic Deposition.

Optimizing the colloidal state of polyamic acid (PAA) nanoparticles is essential for achieving a uniform and high-performance polyimide coating by electrophoretic deposition (EPD) on metal substrates of various shapes. In this paper, we report two important roles of the counterions in the formation of PAA colloids for EPD, which, to date, have not been recognized. First, when tertiary alkyl amines are used to neutralize PAA, the polarity of neutralizing counterions determines the size and stability of the PAA colloidal particles. The polarity can be finely tuned by using two different tertiary alkyl amines containing polar and nonpolar groups and adjusting the molar ratio. Depending on the polar/nonpolar ratio, various states of PAA colloids were obtained, including dissolved state, stable colloid, and aggregates. Second, we observed that the confined counterions inside PAA nanoparticles can act as an imidization catalyst during the thermal annealing process. It is revealed that some fraction of the counterion species, mostly having nonpolar groups, is not drawn toward the counter electrode and remains inside the PAA nanoparticles during the EPD process. Optimizing the polarity eventually allowed us to form uniform EPD coatings with high dielectric strengths.

An improved and one-pot procedure to the synthesis of symmetric amines by domino reactions of 5-methyl-1,3,4-thiadiazole-2-amine, a new nitrogen atom donor, and alkyl halides

A new one-pot method has been introduced in this work for the synthesis of symmetrical primary, secondary, and tertiary alkyl amines from alkyl halides and 5-methyl-1,3,4-thiadiazole-2-amine as a nitrogen-transfer reagent. In this method, all three types of amines have been successfully prepared after changing the ratio of substrates and base control. In addition to the introduction of a new nitrogen-transfer reagent, other important features of this work include normal atmospheric conditions and excellent yields under mild reaction conditions.

One-Pot Synthesis of Hybrid Conjugated Oligomer-Ag Nanoparticles.

Here we report one-pot, straightforward synthesis of hybrid conjugated oligomer-silver nanoparticles (AgNPs) by utilizing tertiary alkyl amine and fluorene-benzothiodiazole-containing conjugated oligomer that both acts as a reducing agent in the reduction of silver ions into metallic silver and as a matrix to accommodate the newly formed AgNPs. By tuning the reaction conditions, it is possible to control the sizes and the structural features of hybrid nanoparticles as either raspberry or core–shell type hybrid structures.

The pKa values of amine based solvents for CO2 capture and its temperature dependence—An analysis by density functional theory

A computational chemistry study has been employed to calculate the pKa values of alkylamines (primary, secondary and tertiary) used in the removal of carbon dioxide. A DFT-B3LYP level of theory with 6-311++G (d, p) basis set is used for the computational analysis. The pKa values of amines are of great importance as it has a major role in carbon dioxide capturing mechanism. The temperature dependence of pKa values has also been evaluated and it has been observed that the pKa values of alkylamines shows an inverse relation with the temperature. The Secondary and tertiary amines show maximum and minimum pKa values respectively. The gas phase proton affinity (PA) and gas the phase basicity (GB), which is difficult to measure experimentally, have been computed easily and accurately by this method. It is observed that the PA and GB values increase from primary to tertiary alkylamines. The linear relationship between the pKa values and the free energy of protonation has been computationally verified; the results are in good agreement with the experimental results and the method is simpler and less expensive. The work can be extended to study the carbamate stability and carbon dioxide capture mechanism and there by screening the candidates for the Carbon dioxide Capture and Storage.

Salt Tunable Rheology of Thixotropic Supramolecular Organogels and Their Applications for Crystallization of Organic Semiconductors.

Physical gelation behaviors of a series of novel bisurea-based derivatives bearing fatty alkyl tertiary amine moieties have been explored in water and common organic solvents. One of these amines exhibits very good thixotropic gels in apolar aromatic solvents (e.g., xylenes). The corresponding sol-gel transition is instantaneous and could be repeated for at least 50 cycles. Interestingly, the elasticity and strength of the resulting gels can be remarkably enhanced initially by the addition of a trace amount of tetrabutylammonium acetate (TBA) followed by a subsequent drop with further salt addition. Temperature-dependent 1H NMR confirmed that hydrogen bonding is the main driving force for the physical gelation. TEM, rheology, 1H NMR titration, and examination of critical gelation concentration (CGC) reveal that the phenomenon is due to the dominated effects, the salting out effect at lower TBA concentration, or the anion-urea hydrogen bonding at higher TBA concentration. Furthermore, the obtained transparent gels in this work can be used as good media for growing crystals of several organic semiconductors.

CO2-Triggered Pickering Emulsion Based on Silica Nanoparticles and Tertiary Amine with Long Hydrophobic Tails.

We describe a strategy of fabricating CO2-triggered oil-in-water Pickering emulsion based on silica nanoparticles functionalized in situ by a trace amount of conventional CO2-switchable surfactant, N-(3-(dimethylamino)propyl)alkyl amide (CnPMA). By alternately bubbling CO2 and N2 at a moderate conditions (30 °C, 80 mL min-1), silica nanoparticles reversibly switch between amphipathic and hydrophilic as a result of the adsorption of ammonium (CO2) and the desorption of tertiary amine (N2). The emulsion can then be smart switched "on (stable)" and "off (unstable)", along with homogenization, without needing cooling and heating. The switching of the current tertiary-based system is simple, moderate, and environmentally friendly, without contamination and the restriction of rigorous conditions. The surfactant concentration window of the Pickering emulsion is closely related to the length of hydrophobic tail, and the upper limit is no more than 0.20 cmc of that of the corresponding ammonium surfactant. Such a strategy is also suitable for commercial alkyl tertiary amines, without needing complicated organic synthesis.

Preparation, evaluation, and application of a novel reversed-phase/zwitterionic/hydrophilic interaction liquid chromatographic mixed-mode stationary phase

ABSTRACTThe present study described the preparation and application of a reversed-phase/zwitterionic/hydrophilic interaction liquid chromatography stationary phase, named as SIL-PS. The SIL-PS was prepared through a four-step reaction, chemical bonding, nucleophilic addition, SN1 substitution, and sulfonation on the silica matrix. It was featured with C12 alkyl chain, quaternary ammonium, tertiary amine, and sulfonate groups. After SIL-PS was packed into the stainless steel column (150 × 2.1 mm i.d.), chromatographic parameters, including acetonitrile content, pH, and ionic strength of the mobile phase, and the column temperature, were systematically investigated to study the retention mechanism. Electrostatic adsorptive/repulsive, partition, and hydrogen-bonding interactions were demonstrated to contribute to the retention. The stability of the SIL-PS was satisfactory, with relative standard deviations of retention factors of 1.93, 2.08, and 1.90% for loxoprofen, adenosine, and liquiritin, respectively. Additionally, to investigate the separation selectivity, the non-steroidal anti-inflammatory drugs, nucleobases/nucleotides, and alkaloids/glycosides were separated; the HPLC fingerprinting of the Cortex phellodendri extract was also conducted, and the separation performance was superior to that of the C18 column in terms of peak shape, resolution, and analytical time. The results revealed that the prepared SIL-PS possessed multifunctionalities for multiretention and could be promising for complicated samples.

Molecular determinants of prokaryotic voltage-gated sodium channels for recognition of local anesthetics.

Local anesthetics (LAs) inhibit mammalian voltage-gated Na(+) channels (Navs) and are thus clinically important. LAs also inhibit prokaryotic Navs (BacNavs), which have a simpler structure than mammalian Navs. To elucidate the detailed mechanisms of LA inhibition to BacNavs, we used NavBh, a BacNav from Bacillus halodurans, to analyze the interactions of several LAs and quaternary ammoniums (QAs). Based on the chemical similarity of QA with the tertiary-alkylamine (TAA) group of LAs, QAs were used to determine the residues required for the recognition of TAA by NavBh. We confirmed that two residues, Thr220 and Phe227, are important for LA binding; a methyl group of Thr220 is important for recognizing both QAs and LAs, whereas Phe227 is involved in holding blockers at the binding site. In addition, we found that NavBh holds blockers in a closed state, consistent with the large inner cavity observed in the crystal structures of BacNavs. These findings reveal the inhibition mechanism of LAs in NavBh, where the methyl group of Thr220 provides the main receptor site for the TAA group and the bulky phenyl group of Phe227 holds the blockers inside the large inner cavity. These two residues correspond to the two LA recognition residues in mammalian Navs, which suggests the relevance of the LA recognition between BacNavs and mammalian Navs.

Supported Gold Nanoparticles for Efficient α‐Oxygenation of Secondary and Tertiary Amines into Amides

Although the α-oxygenation of amines is a highly attractive method for the synthesis of amides, efficient catalysts suited to a wide range of secondary and tertiary alkyl amines using O2 as the terminal oxidant have no precedent. This report describes a novel, green α-oxygenation of a wide range of linear and cyclic secondary and tertiary amines mediated by gold nanoparticles supported on alumina (Au/Al2 O3 ). The observed catalysis was truly heterogeneous, and the catalyst could be reused. The present α-oxygenation utilizes O2 as the terminal oxidant and water as the oxygen atom source of amides. The method generates water as the only theoretical by-product, which highlights the environmentally benign nature of the present reaction. Additionally, the present α-oxygenation provides a convenient method for the synthesis of (18) O-labeled amides using H2 (18) O as the oxygen source.

Supported Gold Nanoparticles for Efficient α‐Oxygenation of Secondary and Tertiary Amines into Amides

AbstractAlthough the α‐oxygenation of amines is a highly attractive method for the synthesis of amides, efficient catalysts suited to a wide range of secondary and tertiary alkyl amines using O2 as the terminal oxidant have no precedent. This report describes a novel, green α‐oxygenation of a wide range of linear and cyclic secondary and tertiary amines mediated by gold nanoparticles supported on alumina (Au/Al2O3). The observed catalysis was truly heterogeneous, and the catalyst could be reused. The present α‐oxygenation utilizes O2 as the terminal oxidant and water as the oxygen atom source of amides. The method generates water as the only theoretical by‐product, which highlights the environmentally benign nature of the present reaction. Additionally, the present α‐oxygenation provides a convenient method for the synthesis of 18O‐labeled amides using H218O as the oxygen source.