Mixtures Of Trimethylamine Research Articles

Methylamine Separations Enabled by Cooperative Ligand Insertion in Copper-Carboxylate Metal-Organic Frameworks.

Monomethylamine (NH2CH3), dimethylamine (NH(CH3)2), and trimethylamine (N(CH3)3) are important chemical feedstocks that are produced industrially as an azeotropic mixture and must be separated using an energy-intensive thermal distillation. While solid adsorbents have been proposed as alternatives to distillation for separating various industrial gas mixtures, methylamine separations remain largely unexplored in this context. Here, we investigate two isoreticular frameworks Cu(cyhdc) (cyhdc2- = trans-1,4-cyclohexanedicarboxylate) and Cu(bdc) (bdc2- = 1,4-benzenedicarboxylate) as prospective candidates for this challenging separation, motivated by the recent discovery that Cu(cyhdc) reversibly captures ammonia through a unique framework-to-coordination polymer phase change. Through a combination of gas adsorption and powder X-ray diffraction analyses, we find that Cu(cyhdc) and Cu(bdc) reversibly bind large quantities of mono- and dimethylamine through framework-to-coordination polymer phase change mechanisms, although both frameworks adsorb only moderate amounts of trimethylamine via physisorption. Single-crystal X-ray diffraction analysis of select mono- and dimethylamine containing phases suggests that the number of hydrogen bond donors available and the linker donor strength are key factors influencing amine uptake. Finally, investigation of the tricomponent adsorption behavior of both materials reveals that Cu(cyhdc) is selective for the capture of monomethylamine from a range of mono-, di-, and trimethylamine mixtures.

Adsorption enhancement of hazardous odor gas using controlled thermal oxidation of activated carbon

Nitrogen-containing odorous compounds (NOCs) such as ammonia, ethylamine, dimethylamine, and trimethylamine (TMA) have potentially adverse effects on the environment and human health. An efficient and simple strategy for NOC removal is necessary. Herein, thermally dried activated carbon adsorbents (TDACs) were prepared, and their surfaces were subjected to controlled thermal oxidation at 50, 100, and 200 °C. The resulting TDACs exhibited micropore-intensive porous structures with different specific surface areas (SSA) (135–562 m2 g−1) and demonstrated 2–38 times higher NOC-adsorption capacity (12.35–102.92 mg g−1) than that of pristine AC in a fixed-bed breakthrough test. Comprehensive surface characterization revealed a correlation between the thermal oxidation conditions and corresponding SSAs. Density functional theory calculations revealed that multidentate hydrogen bonding potential prevails over proton affinity in determining the NOC-adsorption trend. The fractal-like kinetics of the classical adsorption fitting for the TDACs suggested a heterogeneous adsorption behavior (R2 = 0.9998). A competitive adsorption test for the TDACs using a binary mixture of TMA and benzene demonstrated that TMA is favorably adsorbed over benzene and that the co-adsorption process involves a roll-up effect. This study demonstrates that NOC adsorption on TDACs can be controlled via a thermal oxidation strategy, which affords adsorbents with high reusability and adsorbate selectivity.

Absolute primary scintillation yield in gaseous xenon and in Xenon — Trimethylamine mixtures

The primary scintillation signal in gaseous detectors can be used to obtain the initial interaction time of a detected event, but existing results in the literature for its yield in gaseous xenon are scarce and there is not a good agreement between them. In this work, a standard Gas Proportional Scintillation Counter (GPSC) was used to measure the absolute primary scintillation yield of gaseous xenon at 800 Torr for 5.9 keV X-rays, in order to try to clarify its value. The experimental determination was carried out using the ratio between the primary and secondary scintillation signals. The detection efficiencies of both signals were determined by Monte Carlo simulation results were used to correct the measured ratios. A primary scintillation yield of 73.4 ± 8.8 photons by 5.9 keV X-ray was obtained, from which a wp-value, i.e, the average energy necessary to produce a primary scintillation photon in xenon, of 80 ± 12 eV was obtained.Also, in the same conditions, the primary scintillation was studied in Xenon-Trimethylamine (TMA – (CH3)3N), mixtures with TMA fraction between 0.1% and 1.0%. The primary scintillation signal was only observable at the lowest TMA fraction in the mixture (0.1%). For higher fractions, the primary scintillation signal was not observable, indicating that these may not be suitable mixtures for experiments that use the primary scintillation signal.

Measurement of scintillation and ionization yield with high-pressure gaseous mixtures of Xe and TMA for improved neutrinoless double beta decay and dark matter searches

Liquid Xe TPCs are among the most popular choices for double beta decay and WIMP dark matter searches. Gaseous Xe has intrinsic advantages when compared to Liquid Xe, specifically, tracking capability and better energy resolution for double beta decay searches. The performance of gaseous Xe can be further improved by molecular additives such as trimethylamine(TMA), which are expected to (1) cool down the ionization electrons, (2) convert Xe excitation energy to TMA ionizations through Penning transfer, and (3) produce scintillation and electroluminescence light in a more easily detectable wavelength (300 nm). These features may provide better tracking and energy resolution for double-beta decay searches. They are also expected to enhance columnar recombination for nuclear recoils, which can be used for searches for WIMP dark matter with directional sensitivity. We constructed a test ionization chamber and successfully measured scintillation and ionization yields at high precision with various Xe and TMA mixtures and pressures. We observed the Penning effect and an increase in recombination with the addition of TMA. However, many undesired features for dark matter searches, such as strong suppression of the scintillation light and no sign of recombination light, were also found. This work has been carried out within the context of the NEXT collaboration.

Measurements of Charge and Light in Pure High Pressure Xe towards the Study of Xe+TMA Mixtures with Dark Matter Directionality Sensitivity and Supra-intrinsic Energy Resolution for 0νββ Decay Searches

Trimethylamine (TMA) may improve the energy resolution of gaseous xenon based detectors for 0νββ decay searches through the reduction of the Fano factor by the Penning effect. This molecule may also be the key for sensing directionality of nuclear recoils induced by Weakly Interacting Massive Particles (WIMPs) in monolithic massive (ton-scale) detectors, without the need of track imaging, by making use of columnar recombination. Nuclear recoil directionality may be the path for a definite discovery of the WIMP nature of Dark Matter. An ionization chamber has been constructed and operated to explore the properties of high pressure gaseous Xe + TMA mixtures for particle detection in rare-event experiments. The ionization, scintillation and electroluminescence (EL) signals are measured as function of pressure and electric field. We present results for pure xenon at pressures up to 8bar. This work has been carried out within the context of the NEXT collaboration.

Tuning the halogen/hydrogen bond competition: a spectroscopic and conceptual DFT study of some model complexes involving CHF2I.

Insight into the key factors driving the competition of halogen and hydrogen bonds is obtained by studying the affinity of the Lewis bases trimethylamine (TMA), dimethyl ether (DME), and methyl fluoride (MF) towards difluoroiodomethane (CHF(2) I). Analysis of the infrared and Raman spectra of solutions in liquid krypton containing mixtures of TMA and CHF(2) I and of DME and CHF(2) I reveals that for these Lewis bases hydrogen and halogen-bonded complexes appear simultaneously. In contrast, only a hydrogen-bonded complex is formed for the mixtures of CHF(2) I and MF. The complexation enthalpies for the C-H⋅⋅⋅Y hydrogen-bonded complexes with TMA, DME, and MF are determined to be -14.7(2), -10.5(5) and -5.1(6) kJ mol(-1), respectively. The values for the C-I⋅⋅⋅Y halogen-bonded isomers are -19.0(3) kJ mol(-1) for TMA and -9.9(8) kJ mol(-1) for DME. Generalization of the observed trends suggests that, at least for the bases studied here, softer Lewis bases such as TMA favor halogen bonding, whereas harder bases such as MF show a substantial preference for hydrogen bonding.

The potential role of wound-activated volatile release in the chemical defence of the brown alga Dictyota dichotoma: Blend recognition by marine herbivores

The chemical defence potential against herbivores of certain Dictyotalean brown algae increases after tissue disruption. This wound activated defence has been explored in bioassays, but the metabolic pathways behind it are unknown. Here we describe a metabolic profiling approach to identify the activated defence metabolites. Before and after tissue damage of Dictyota dichotoma modified diterpenes, non-volatile medium polar metabolites as well as volatile compounds were profiled. While comparison of extracted intact and mechanically wounded algae revealed no significant differences in structure and distribution of semi-volatile and reversed phase LC/MS detectable metabolites, a strong release of gaseous volatiles was observed. Solid phase micro extraction (SPME) and GC/MS were used for identification and quantification of these biogenic gases. This showed that D. dichotoma released elevated amounts of trimethylamine (TMA) and dimethylsulphide (DMS) after mechanical tissue damage. To study the ecological significance of compounds released post injury and of the biosynthetically connected non-volatile acrylate, choice assays were performed with the amphipod Amphithoe longimana. Behavioural assays on artificial diets did not reveal any repellent role for the single isolated metabolites. In strong contrast, a mixture of TMA, DMS and acrylate significantly reduced the association of the herbivores with the treated food pellets.This shows that mixtures of these biogenic gases and acrylate are recognized by the herbivores and influence food selection.

Effect of trimethylamine on acetate utilization by Methanosarcina barkeri

During growth of Methanosarcina barkeri strain Fusaro on a mixture of trimethylamine and acetate, methane production and acetate consumption were biphasic. In the first phase trimethylamine (33 mmol x l-1) was depleted and some acetate (11–14 from 50 mmol x l-1) was metabolized simultaneously. In the second phase the remaining acetate was cleaved stoichiometrically into CH4 and CO2. Kinetic experiments with (2-14C)acetate revealed that only 2.5% of the methane produced in the first phase originated from acetate: 18% of the acetate metabolized was cleaved into CH4 and CO2, 23% of the acetate was oxidized, and 55% was assimilated. Methane produced from CD3−COOH in the first phase consisted of CD2H2 and CD3H in a ratio of 1:1.

Effects of Structural Modifications on the Activity of Hippelates Eye Gnat 1 Attractants and Coattractants

An aqueous mixture of trimethylamine, ammonia, linoleic acid, and indole acidified to p H 6 with acetic acid attracts the eye gnat Hippelates collusor (Townsend). To study the influence of structural modifications of these active components on attractancy, we bioassayed homologs and analogs of the against field populations of the insects. Primary and secondary aliphattc amines either decreased or did not influence the attractancy of a composition containing ammonia, linoleic acid, and indole acidified with acetic acid to p H 6. With the exception of tripropylamine, all tertiary amines tested enhanced the attractancy of the composition. Cyclic amines reduced it. When a low-molecular aliphatic carboxylic acid was used to aCidify a composition containing trimethylamine, ammonia, linoleic acid, and indole to p H 6, those acidified with acetic, propionic, or n -butyric acid showed the greatest attractancy. The addition of linoleic or oleic acid to a composition containing trimethylamme, ammonia, and indole acidified to p H 6 with acetic acid increased the activity of the composition. Saturated fatty acids usually lowered it. Among unsaturated fatty acids tested, only those having 18 carbon atoms with a cis double. bond at the 9 positon or 2 cis double bonds at the 9 and 12 positions were effective in increasing the activity.

Attractants for Synanthropic Flies: Evaluation of Chemical Attractants and Coattractants Against the Eye Gnat Hippelates collusor (Diptera-Chloropidae) 1

To study the influence of individual attractants and coattractants, their concentrations, p H, and age-efficacy relationship, various attractant mixtures were prepared and bioassayed against field populations of the eye gnat, Hippelates collusor (Townsend). An aqueous mixture of trimethylamine, ammonia, linoleic acid, indole, and acetic acid showed the greatest attractancy at p H 6.0. All these compounds were essential in inducing a high level of response in these insects. A simultaneous increase in the concentrations of trimethylamine, ammonia, indole, and acetic acid did not increase the attractancy. On the contrary, the attractancy significantly declined at very high concentrations. Aging of attractant mixtures at various strengths did not affect activity at 26–28°C for 72 h, but the attractancy of the mixtures decreased somewhat at 32.2°C after 24–120 h. Studies on the effects of the concentration of each attractant and coattractant on the activity showed that optimum concentrations of trimethylamine, ammonia, linoleic acid, and indole were 0.1–5.0, 0.5–5.0, 0.01–0.05, and 0.001–0.01%, respectively. n -Butyric acid at 1% concentration also enhanced the attractancy. This information is basic to the development of potent synthetic attractant formulations for the control of Hippelates eye gnats.