2-methylheptane Research Articles

Sustainable Aviation Fuel Molecules from (Hemi)Cellulose: Computational Insights into Synthesis Routes, Fuel Properties, and Process Chemistry Metrics.

Production of sustainable aviation fuels (SAFs) can significantly reduce the aviation industry's carbon footprint. Current pathways that produce SAFs in significant volumes from ethanol and fatty acids can be costly, have a relatively high carbon intensity (CI), and impose sustainability challenges. There is a need for a diversified approach to reduce costs and utilize more sustainable feedstocks effectively. Here, we map out catalytic synthesis routes to convert furanics derived from the (hemi)cellulosic biomass to alkanes and cycloalkanes using automated network generation with RING and semiempirical thermochemistry calculations. We find >100 energy-dense C8-C16 alkane and cycloalkane SAF candidates over 300 synthesis routes; the top three are 2-methyl heptane, ethyl cyclohexane, and propyl cyclohexane, although these are relatively short. The shortest, least endothermic process chemistry involves C-C coupling, oxygen removal, and hydrogen addition, with dehydracyclization of the heterocyclic oxygens in the furan ring being the most endothermic step. The global warming potential due to hydrogen use and byproduct CO2 is typically 0.7-1 kg CO2/kg SAF product; the least CO2 emitting routes entail making larger molecules with fewer ketonization, hydrogenation, and hydrodeoxygenation steps. The large number of SAF candidates highlights the rich potential of furanics as a source of SAF molecules. However, the structural dissimilarity between reactants and target products precludes pathways with fewer than six synthetic steps, thus necessitating intensified processes, integrating multiple reaction steps in multifunctional catalytic reactors.

Fusion method for sample preparation for isotopic composition determination of boron in refractory materials by thermal ionization mass spectrometry with validation using dissolved and purified samples

Various refractory samples of boron such as titanium borides, rare earth borides, boron carbides having natural and non-natural isotopic composition were analysed by thermal ionization mass spectrometry as Na2BO2+ ions. Samples were fused with Na2CO3 directly on the filament after adjusting the B/Na mole ratio to 2 and in certain cases modifications in the loading technique were required to obtain precise 10B/11B isotopic ratio. A few of the samples expected to have natural 10B/11B ratio were observed to be slightly enriched in 10B. Dissolved samples as well as boron purified by extraction with 5% 2-Ethyl Hexane Diol(EHD) were analysed for 10B/11B ratio to ascertain the accuracy of the results obtained by the direct fusion method. Precision of about 0.02% (1RSD) was obtained for 10B/11B isotopic ratio measured in all the three types of samples. A good agreement of the dissolved sample and purified boron fraction with the directly fused sample validated the direct fusion method as a fast and reliable technique for isotopic analysis of boron in refractory samples.

Conversion of 5-Methyl-3-Heptanone to C8 Alkenes and Alkane over Bifunctional Catalysts

A one-step catalytic process was used to catalyze the hydrodeoxygenation of 5-methyl-3-heptanone (C8 ketone) to a mixture of 5-methyl-3-heptene, 5-methyl-2-heptene (C8 alkenes), and 3-methyl heptane (C8 alkane). High conversion of C8 ketone to the desired products was achieved over a single bed of a supported catalyst (bifunctional heterogeneous catalyst) consisting of one transition metal (copper (Cu) or platinum (Pt)) loaded on alumina (Al2O3) under mild operating conditions (reaction temperatures were varied between 180 °C to 260 °C, and the pressure was 1 atm). The C8 ketone was hydrogenated to 5-methyl-3-heptanol (C8 alcohol) over metal sites, followed by dehydration of the latter on acid sites on the support to obtain a mixture of C8 alkenes. These C8 alkenes can be further hydrogenated on metal sites to make a C8 alkane. The results showed that the main products over copper loaded on alumina (20 wt% Cu–Al2O3) were a mixture of C8 alkenes and C8 alkane in different amounts depending on the operating conditions (the highest selectivity for C8 alkenes (~82%) was obtained at 220 °C and a H2/C8 ketone molar ratio of 2). However, over platinum supported on alumina (1 wt% Pt–Al2O3), the major product was a C8 alkane with a selectivity up to 97% and a conversion of 99.9% at different temperatures and all H2/C8 ketone ratios.

Essential Oil Constituents of Seeds and Fresh Leaves of Garden Lettuce (Lactuca sativa L.) Grown in Isfahan, Iran

Background and objectives: Garden lettuce, Lactuca sativa L. (Asteraceae), is an herbaceous plant cultivated in different parts of Iran including Isfahan. In Iranian traditional medicine, it is classified as a medicinal food because it is nutritive and has therapeutic effects. As the therapeutic effects of the plant parts may be related to some volatile active constituents, it was aimed to determine the chemical constituents of the essential oils obtained from seeds and fresh leaves of the plant grown in Isfahan. Methods: Essential oils from seeds and fresh leaves of Lactuca sativa L. were obtained by hydro-distillation method and were analyzed by gas chromatography-mass spectroscopy (GC/MS) method. Results: Identified volatile constituents in the essential oils of the seeds and fresh leaves samples were representing 96.1% and 91.8% of the oils, respectively. Major volatile constituents of the seeds oil were: linoleic acid (38.8%), oleic acid (17.9%), palmitic acid (4.9%), 3-methyl heptane (3.2%), 1-decene (2.8%), 1-hexyl-3-methyl cyclopentane (2.3%), 2,4-decadienal (E,E) (2.2%), limonene (2.1%) and carvone (2.0%). While the main volatile constituents of the fresh leaves oil were: linoleic acid (37.7%), oleic acid (19.6%), palmitic acid (16.7%), 3-methyl heptane (4.6%), 1-ethyl-3-methyl cyclopentane (4.2%), 1-decene (2%), n-octadecane (1.7%) and n-tetradecane (1.5%). Conclusion: Theessential oils from the seeds and fresh leaves of the plant grown in Isfahan mainly composed of a mixture of saturated and unsaturated fatty acids.

Examination of regional ozone formation: POCPs for Western Australia and comparisons to other continents

Airshed modeling to determine photochemical ozone creation potentials (POCPs) provides a means of ranking regional emission contributions of individual volatile organic compounds (VOC) to O3 formation. Here POCPs are determined for Perth, Western Australia and compared with those from other Continents; Europe (UK), America (USA) and Asia (The Pearl River Delta and Hong Kong). Considering only the commonality of VOC across the top 50 ranked VOC by POCP and top 15 ranked VOC by POCP-weighted emission, indicates a group of 27 alkane, alkene, aromatic and oxygenated VOC that should be considered as useful targets in emission limitation and reduction strategies. This target group includes; ethene, propene, the butenes (6 VOC) and pentenes (3 VOC), trimethyl benzenes (2 VOC), xylenes (3 VOC), toluene, ethyl benzene, m-ethyl toluene, butanes (2 VOC), pentanes (2 VOC) and 2-methyl heptane, as well as methanal, ethanal and methyl-i-butyl ketone. The top 50 ranked VOC by POCP (from >130 VOC) also highlights those more reactive VOC that should be taken note of, as potential high ozone contributors, should emissions increase.

Development of methodology for the determination of boron in ThO2 employing spectrophotometry

Boron was determined in ThO2 employing spectrophotometry using curcumin as complexing agent after dissolution with 85 % ortho phosphoric acid and separation of boron with 10 % 2-ethyl hexane 1,3 diol in CHCl3. The methodology was validated by employing ThO2 standards made from inter laboratory comparison experiments DAE, India. Absolute detection limit of the methodology was found to be 30 ng. Precision and accuracy of the methodology were found to be 4.2 and 2 % respectively. The expanded uncertainty in measurement of boron (at coverage factor 2) was estimated as per ISO guidelines employing bottom-up approach and it was found to be 9.2 %.

The combustion kinetics of a synthetic paraffinic jet aviation fuel and a fundamentally formulated, experimentally validated surrogate fuel

A surrogate fuel is formulated in an a priori manner through a combustion property matching technique to emulate the gas phase chemical kinetic combustion phenomena of S-8 POSF 4734, an alternative aviation fuel derived from natural gas via the Fischer–Tropsch process. A fundamental concept is described which identifies n-dodecane and iso-octane as being appropriate surrogate fuel components for the non-aromatic synthetic fuels. The performance of the formulated 51.9/48.1mole % n-dodecane/iso-octane mixture as a surrogate for the target real fuel is evaluated by the measurement of a series of combustion phenomena exhibited by both fuels including:(1)The oxidative reactivity of stoichiometric mixtures of each fuel in O2/N2 at 12.5atm and 500–1050K, for a residence time of 1.8s at a fixed carbon content of 0.3% using a variable pressure flow reactor.(2)The autoignition behavior of stoichiometric mixtures of each fuel in air at compressed conditions of 667–1223K and ∼20atm by the reflected shock technique.(3)The strained extinction limits of diffusion flames of each fuel at 1atm.The performance of available kinetic models for n-dodecane/iso-octane mixtures is evaluated by analysis of their computations of this experimental data. Furthermore, the impact of oxidation kinetics unique to the mono methylated alkanes which are the dominant molecular structure in synthetic fuels is examined by an experimental study involving the formulation of an n-decane/iso-octane mixture as a surrogate fuel for 2-methyl heptane, a proposed model molecule for such real fuel components.

Computer simulation study of water/hydrocarbon interfaces: Effects of hydrocarbon branching on interfacial properties

We review here the results of our molecular dynamics (MD) simulation study of water/hydrocarbon liquid/liquid interfaces. In order to examine the effects of chain length and branching on interfacial properties, we considered five different alkanes (n-pentane, 2-methyl pentane, 2,2,4-trimethyl pentane, 2-methyl heptane, and n-octane) as the hydrocarbon phase. We used a recently-proposed procedure to identify molecular surface sites and constructed intrinsic density profiles, in addition to the more familiar laboratory-frame profiles, in order to determine the effects of interface fluctuations on the structure and dynamics of the two phases. We found that interfacial properties of the aqueous phase are relatively insensitive to the molecular structure of the hydrocarbon, even though both branching and chain length have significant influence on the hydrocarbon interfacial properties. We found that translational and rotational mobilities of molecules of both phases are affected by the presence of the interface and that rotational relaxation of water molecules is significantly more anisotropic in the interfacial region than in the bulk.

Determination of boron in uranium–aluminum–silicon alloy by spectrophotometry and estimation of expanded uncertainty in measurement

Quantification of boron in diverse materials of relevance in nuclear technology is essential in view of its high thermal neutron absorption cross section. A simple and sensitive method has been developed for the determination of boron in uranium–aluminum–silicon alloy, based on leaching of boron with 6 M HCl and H 2O 2, its selective separation by solvent extraction with 2-ethyl hexane 1,3-diol and quantification by spectrophotometry using curcumin. The method has been evaluated by standard addition method and validated by inductively coupled plasma-atomic emission spectroscopy. Relative standard deviation and absolute detection limit of the method are 3.0% (at 1 σ level) and 12 ng, respectively. All possible sources of uncertainties in the methodology have been individually assessed, following the International Organization for Standardization guidelines. The combined uncertainty is calculated employing uncertainty propagation formulae. The expanded uncertainty in the measurement at 95% confidence level (coverage factor 2) is 8.840%.

Surface fluctuations at the liquid-liquid interface

Within the capillary-wave model (CWM), the liquid-vapor interface is a hypothetical two-dimensional surface whose deviations from planarity are represented as long wavelength capillary waves. We modify the CWM for liquid-liquid interfaces and treat them as two harmonically interacting surfaces (model 1). Corrections to the model are proposed to prevent the usual divergence of the capillary-wave broadening in the thermodynamic limit by introducing a surface-bulk coupling (model 2) and to incorporate the curvature of the two surfaces (model 3). Expressions for the capillary-wave contribution to the surface tension of the interface are obtained. Molecular dynamics simulations are performed for two series of water-hydrocarbon interfacial systems (a) n -pentane, 2-methyl pentane, and 2,2,4-trimethyl pentane (constant chain length) and (b) n -octane, 2-methyl heptane, and 2,2,4-trimethyl pentane (constant molecular mass). A simple procedure to identify the molecular sites at the surface is utilized for a molecular representation of the surface. The distribution of these surface sites as well as the wave-vector dependence of surface fluctuations are analyzed in order to extract the parameters required for model 2. A small length scale is identified above which surface fluctuations correspond to capillary-wave fluctuations thereby connecting the molecular and mesoscopic scales. This approach is applied to all interfacial systems studied here and predictions based on the parameters found to be in good agreement with independent simulation results for surface tension and interfacial widths. Hydrocarbon branching has a small effect on model parameters.

Spectrophotometric determination of boron in nuclear grade uranium compounds with curcumin and studies on effect of HNO3

Detailed investigations have been carried out on the well-known method of spectrophotometric determination of boron particularly in uranium compounds as boron-curcumin complex after extraction into 2-ethyl hexane 1,3-diol (EHD) to understand a number of parameters, which have not been addressed earlier in the literature. These include (i) effect of different acid media on analytical results of boron which are employed for dissolution of nuclear fuel samples, (ii) effect of diluents namely ethyl alcohol and N,N-dimethyl formamide on sensitivity of method which are employed for final dilution, and (iii) studies on loss of boron, if any, during conversion of uranium compounds to U3O8. Based on the present studies, the existing procedure has been suitably modified to improve the sensitivity in the measurements. In addition, this paper also describes about interference studies with Al, Cr, Mg, Ca, Fe, Mn, Mo, F− and W and amount of EHD on modified method. Absolute detection limit was found to be 10 ng. The precision and accuracy of the method, is 3% at level 100 ng·g−1 of boron.

Determination of boron in water samples by chemical prompt gamma neutron activation analysis

Boron concentration has been determined in groundwater samples, collected from Khuchch, Gujarat, India, by prompt gamma neutron activation analysis (PGNAA) after selective separation and pre-concentration by solvent extraction with 10% 2-ethyl hexane 1,3-diol in CHCl3. Solvent extraction separation helped to eliminate the interfering elements in PGNAA determination of boron. The sensitivity of PGNAA is found to be 18.83 cps/mg B based on the slope of a calibration plot obtained by carrying out measurements on synthetic boric acid samples containing boron in the range of 30–150 μg. Detection limit of the method is 0.2 μg/g counted for 35,000 seconds at a sample size of 15 gram. The precision (relative standard deviation at 1σ level) and accuracy of the method is 5%. The analytical results of the present method agreed well with well-established spectrophotometric determination of boron as boron-curcumin complex and inductively coupled plasma atomic emission spectroscopy (ICP-AES).

Water−Hydrocarbon Interfaces: Effect of Hydrocarbon Branching on Interfacial Structure

Molecular dynamics simulation are performed for the water/hydrocarbon system to study the effect of hydrocarbon branching on interfacial properties. The following two series of hydrocarbons are considered: (1) n-pentane, 2-methyl pentane, and 2,2,4-trimethyl pentane (constant chain length) and (2) n-octane, 2-methyl heptane, and 2,2,4-trimethyl pentane (constant molecular mass). With a simple algorithm for identification of surface sites and mapping nonsurface sites to these surface sites, intrinsic profiles were constructed with respect to the surface layer. Intrinsic density profiles for water and hydrocarbons with respect to the hydrocarbon and water surface, respectively, resemble density profiles of liquids in the presence of a wall. Order parameters were used to study orientation of molecules with respect to the surface normal and the hydrogen bond network was characterized in terms of the number of hydrogen bonds per water molecule and percentage of hydrogen bonded molecules in the first coordination shell. The corresponding intrinsic profiles were obtained. The O-H bond for surface water was found to have two preferential orientations, pointing toward the hydrocarbon phase and parallel to the interface. Hydrocarbon molecules in series 1 orient along the interface with the more branched molecule better aligned. For molecules in series 2, the larger molecular length reduces the alignment of molecules along the interface.

Determination of Boron in U3O8 by Spectrophotometry

Spectrophotometric estimation of boron with curcumin after extraction employing 10% 2-ethyl hexane 1,3-diol (EHD) in CHC13 has been modified and employed for its determination in U3O8.The method gives a precision and accuracy of 4.0% at 100 ppb of boron when about 200 mg sample is taken for analysis; the detection limit is 32 ng of boron. If the availability of the sample is limited and the boron content is low, lower dilutions are resorted to realize the desired sensitivity in the measurements (diluting to 10 mL instead of 25 mL). Interference of different acid media is also discussed.

Extraction of the soluble material from the shells of the bacuri fruit ( Platonia insignis Mart) with pressurized CO 2 and other solvents

The extraction of soluble material from bacuri shells has been studied. The effects of pressure, temperature, particle size, static period and flow time were investigated for extraction with liquid carbon dioxide (LCO 2). The yield and the composition of the extracts obtained with LCO 2 were compared with those for extracts obtained with other techniques, such as LCO 2 plus ethanol (LCO 2-EtOH), supercritical CO 2 (SCO 2), steam distillation (SD), cold ethanol (C-EtOH), and Soxhlet extraction with ethanol (EtOH-So). The LCO 2 and LCO 2-EtOH extractions were performed at pressures of 63–70 bar, and temperatures of 16–21°C. The constituents isolated from the bacuri shell extracts were predominantly free fatty acids: palmitic, oleic, linoleic, α-linolenic, and stearic acids. In addition to these fatty acids, the LCO 2-EtOH extracts contained caprylic and myristic acids, alcohols (linalool and 3,7-dimethyl oct-1-en-3,7-diol), and the phenol ether eugenol. The SCO 2 extraction was performed at 200 bar and 50°C. The SCO 2 extract had a composition similar to the LCO 2 extract, but the α-linolenic acid was not present, although hydrocarbons such as β-bisabolene, and alcohols such as 3,7-dimethyl-1-octen-3,7-diol, linalool, and α-terpineol were identified. In the extract obtained by SD, only hydrocarbons (methyl benzene and 2-methyl heptane), alcohols (linalool and α-terpineol), and oxides ( cis-linalool oxide and trans-linalool oxide) were identified. In the C-EtOH and EtOH-So extracts only trimethyl citrate was identified.

Confined thin films of a linear and branched octane. A comparison of the structure and solvation forces using molecular dynamics simulations

Experiments using the surface force apparatus indicate that the nature of the forces acting on two surfaces separated by liquid film less than 5.0 nm thick are extremely sensitive to the chemical structure of the molecules in the liquid. Using molecular dynamics simulations we probe the structure and solvation forces upon two model surfaces separated by liquid hydrocarbons. We examine two cases—films composed of n-octane and films composed of iso-octane (2-methyl heptane). At certain surface separations the liquid films are strongly layered with chains lying parallel to the surface. These films produce a repulsive force equivalent to as much as 100 MPa on the surfaces, while exhibiting liquidlike self-diffusion constants with no evidence of solidification or glassification. A plot of this force, known as the solvation force, as a function of surface separation reveals strong oscillations with a period of about 0.4–0.5 nm for both the linear and branched molecules. Although the branching in the iso-octane significantly reduces the intensity of the layering, its solvation force curve shows oscillations which are just as strong as those seen in the films of the linear octane. This contradicts experimental results showing that the addition of a single methyl side chain significantly reduces the oscillatory nature of the solvation forces.

(115)2-エチルヘキセン-1および3-メチルヘプタンの芳香族化反応

(115)2-エチルヘキセン-1および3-メチルヘプタンの芳香族化反応

Effect of 2, Methyl Amino Heptane Upon Cardiac Automaticity During Cyclopropane Anesthesia in Dogs

SummaryIn 5 dogs premedicated with morphine and scopolamine and anesthetized with cyclopropane, 2-methyl amino heptane (EA-1) caused sinus and auricular paroxysmal tachycardia, and ventricular premature beats. Ventricular paroxysmal tachycardia and auricular and ventricular fibrillations were not observed.