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Yongsong Huang - One of the best experts on this subject based on the ideXlab platform.
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Successional blooms of alkenone-producing haptophytes in Lake George, North Dakota: Implications for continental paleoclimate reconstructions
Limnology and Oceanography, 2019Co-Authors: Susanna Theroux, Yongsong Huang, Jaime L. Toney, Robert A. Andersen, Paul Nyren, Rick Bohn, Jeffrey M. Salacup, Leslie G. Murphy, Linda Amaral-zettlerAbstract:Alkenone‐derived paleotemperature reconstruction holds great promise in lake environments. However, the occurrence of multiple species of alkenone‐producing haptophyte algae in a single lake can complicate the translation of alkenone unsaturation to temperature if each species requires an individual temperature calibration. Here, we present the first systematic monitoring of two alkenone‐producing haptophytes throughout the course of a seasonal cycle in Lake George, North Dakota, using a combined approach of DNA sequencing and alkenone lipid characterization. Field sampling revealed a nonoverlapping haptophyte succession, with both an early and late season haptophyte bloom event. Culturing experiments demonstrated that the two haptophyte species responsible for these blooms had statistically similar alkenone‐temperature responses, although the culture‐based calibrations were distinct from the in situ calibration. Bloom timing of each haptophyte species corresponded to surface‐water temperatures that differed by more than 10°C, revealing that changes in bloom intensities for each species will skew the sediment‐inferred temperatures to a different stage of the growth season. These results highlight the importance of accounting for bloom timing when interpreting alkenone‐derived temperatures in sediment cores, especially in lakes that experience large seasonal fluctuations in water column temperature and salinity.
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Phylogenetic diversity in freshwater-dwelling Isochrysidales haptophytes with implications for alkenone production
Geobiology, 2019Co-Authors: Nora Richter, William M. Longo, Yongsong Huang, Sarabeth George, Anna Shipunova, Linda Amaral-zettlerAbstract:Members of the order Isochrysidales are unique among haptophyte lineages in being the exclusive producers of alkenones, long-chain ketones that are commonly used for paleotemperature reconstructions. Alkenone-producing haptophytes are divided into three major groups based largely on molecular ecological data: Group I is found in freshwater lakes, Group II commonly occurs in brackish and coastal marine environments, and Group III consists of open ocean species. Each group has distinct alkenone distributions; however, only Groups II and III Isochrysidales currently have cultured representatives. The uncultured Group I Isochrysidales are distinguished geochemically by the presence of tri-unsaturated alkenone isomers (C37:3b Me, C38:3b Et, C38:3b Me, C39:3b Et) present in water column and sediment samples, yet their genetic diversity, morphology, and environmental controls are largely unknown. Using small-subunit (SSU) ribosomal RNA (rRNA) marker gene amplicon high-throughput sequencing of environmental water column and sediment samples, we show that Group I is monophyletic with high phylogenetic diversity and contains a well-supported clade separating the previously described "EV" clade from the "Greenland" clade. We infer the first partial large-subunit (LSU) rRNA gene Group I sequence phylogeny, which uncovered additional well-supported clades embedded within Group I. Relative to Group II, Group I revealed higher levels of genetic diversity despite conservation of alkenone signatures and a closer evolutionary relationship with Group III. In Group I, the presence of the tri-unsaturated alkenone isomers appears to be conserved, which is not the case for Group II. This suggests differing environmental influences on Group I and II and perhaps uncovers evolutionary constraints on alkenone biosynthesis.
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widespread occurrence of distinct alkenones from group i haptophytes in freshwater lakes implications for paleotemperature and paleoenvironmental reconstructions
Earth and Planetary Science Letters, 2018Co-Authors: William M. Longo, Jiaju Zhao, Yongsong Huang, Anne E. Giblin, Yuan Yao, Xian Wang, Roland Zech, Torsten Haberzettl, Ludwig JardillierAbstract:Abstract Alkenones are C35–C42 polyunsaturated ketone lipids that are commonly employed to reconstruct changes in sea surface temperature. However, their use in coastal seas and saline lakes can be hindered by species-mixing effects. We recently hypothesized that freshwater lakes are immune to species-mixing effects because they appear to exclusively host Group I haptophyte algae, which produce a distinct distribution of alkenones with a relatively consistent response of alkenone unsaturation to temperature. To evaluate this hypothesis and explore the geographic extent of Group I haptophytes, we analyzed alkenones in sediment and suspended particulate matter samples from lakes distributed throughout the mid- and high latitudes of the Northern Hemisphere ( n = 30 ). Our results indicate that Group I-type alkenone distributions are widespread in freshwater lakes from a range of different climates (mean annual air temperature range: −17.3–10.9 °C; mean annual precipitation range: 125–1657 mm yr−1; latitude range: 40–81°N), and are commonly found in neutral to basic lakes (pH > 7.0), including volcanic lakes and lakes with mafic bedrock. We show that these freshwater lakes do not feature alkenone distributions characteristic of Group II lacustrine haptophytes, providing support for the hypothesis that freshwater lakes are immune to species-mixing effects. In lakes that underwent temporal shifts in salinity, we observed mixed Group I/II alkenone distributions and the alkenone contributions from each group could be quantified with the RIK37 index. Additionally, we observed significant correlations of alkenone unsaturation ( U 37 K ) with seasonal and mean annual air temperature with this expanded freshwater lakes dataset, with the strongest correlation occurring during the spring transitional season ( U 37 K = 0.029 ⁎ T − 0.49 ; r 2 = 0.60 ; p 0.0001 ). We present new sediment trap data from two lakes in northern Alaska (Toolik Lake, 68.632°N, 149.602°W; Lake E5, 68.643°N, 149.458°W) that demonstrate the highest sedimentary fluxes of alkenones in the spring transitional season, concurrent with the period of lake ice melt and isothermal mixing. Together, these data provide a framework for evaluating lacustrine alkenone distributions and utilizing alkenone unsaturation as a lake temperature proxy.
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identification of double bond positions in isomeric alkenones from a lacustrine haptophyte
Rapid Communications in Mass Spectrometry, 2016Co-Authors: James T Dillon, William M. Longo, Yifan Zhang, Rafael Torozo, Yongsong HuangAbstract:RATIONALE Measurements of alkenone unsaturation ratios are widely used for paleotemperature reconstructions in ocean and lake environments. Previously, we reported the discovery of a series of tri-unsaturated alkenone positional isomers (Δ(14, 21, 28) ) from oligosaline and freshwater lakes in Greenland and Alaska. In this work we provide a detailed analysis of the structures and isotopic compositions (δ(13) C and δ(2) H) of the alkenones produced by the "Greenland haptophyte". METHODS Alkenones were extracted from sediments of Lake BrayaSo, Greenland. Alkenone double-bond positions were determined by GC/EI-MS analysis of alkenone dimethyl disulfide and cyclobutylimine derivatives. Alkenones were purified by semi-preparative HPLC using a silver(I) thiolate stationary phase. Carbon and hydrogen isotope analysis was performed by gas chromatography/isotope ratio mass spectrometry (GC/IRMS). RESULTS A series of novel tri-unsaturated alkenone positional isomers were identified among four alkenone homologues (i.e. C37 Me , C38 Me , C38 Et , and C39 Et ) with double-bond positions at Δ(14, 21, 28) . The hydrogen isotope compositions (δ(2) H, VSMOW) of the tri-unsaturated positional isomers from C37 Me and C38 Et were slightly depleted (~ -11 ‰) relative to the common tri-unsaturated alkenone. The carbon isotope composition (δ(13) C, VPDB) of the tri-unsaturated positional isomers from the C37 Me , C38 Me , C38 Et , and C39 Et alkenones were significantly enriched (~ +4 ‰) relative to the common alkenones (di-, tri-, and tetra-unsaturated). CONCLUSIONS The novel tri-unsaturated alkenone positional isomers produced by the Greenland haptophyte possess Δ(14, 21, 28) double-bond positions, instead of the common Δ(7, 14, 21) double-bond positions. The hydrogen isotope values suggest the novel tri-unsaturated positional isomers could be biosynthetic precursors to the tetra-unsaturated alkenones (Δ(7, 14, 21, 28) ). However, the significantly higher carbon isotope values of the tri-unsaturated positional isomers relative to the common di-, tri- and tetra-unsaturated alkenones suggest these positional isomers may have different/additional biosynthetic precursors.
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Production and temperature sensitivity of long chain alkenones in the cultured haptophyte Pseudoisochrysis paradoxa
Organic Geochemistry, 2013Co-Authors: Susanna Theroux, Jaime L. Toney, Linda A. Amaral-zettler, Yongsong HuangAbstract:The alkenone unsaturation index (U37K or U37K′) serves as a critical tool for reconstructing temperature in marine environments. Lacustrine haptophyte algae are genetically distinct from their ubiquitous and well studied marine counterparts, and the unknown species-specific genetic imprints on long chain alkenone production by lacustrine species have hindered the widespread application of the U37K temperature proxy to lake sediment records. The haptophyte Pseudoisochrysis paradoxa produces alkenones but its U37K calibration has never been determined. It has an alkenone fingerprint abundant in tetraunsaturated alkenones, a hallmark of lacustrine environments. We present here the first calibration of the U37K index to temperature for a culture of P. paradoxa. We found that the U37K index accurately captured the alkenone response to temperature whereas the U37K′ index failed to do so, with U37K′ values below 0.08 projecting to two different temperature values. Our results add a fifth species-specific U37K calibration and provide another line of evidence that different haptophyte species require different U37K calibrations. The findings also highlight the necessary inclusion of the C37:4 alkenone when reconstructing temperatures from P. paradoxa-derived alkenone records.
Isaías García De La Fuente - One of the best experts on this subject based on the ideXlab platform.
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orientational effects in Alkanone alkanal or dialkyl carbonate alkane mixtures and in Alkanone Alkanone or dialkyl carbonate systems
Journal of Molecular Liquids, 2017Co-Authors: Fernando . Hevia, Juan Antonio . González, Isaías García De La Fuente, Cristina Alonsotristan, Luis Felipe . SanzAbstract:Abstract Interactions and structure of Alkanone, or alkanal or dialkyl carbonate + alkane mixtures, or of 2-Alkanone + 2-Alkanone, or of ketone + dialkyl carbonate systems have been investigated by means of a set of thermodynamic properties and by the application of the Flory model. The properties considered are excess molar quantities: enthalpies, H m E , volumes, V m E , or isobaric heat capacities, C pm E , and liquid-liquid equilibria. Experimental data show that alkane mixtures are characterized by rather strong dipolar interactions. In the case of systems containing ketones with the same number of C atoms and a given alkane, dipolar interactions become weaker in the sequence: aromatic > cyclic > linear. In addition, the mentioned interactions become also weaker in the order: dialkyl carbonate > linear Alkanone > linear alkanal. This is an important result, as carbonates show lower effective dipole moments than the other compounds, and it suggests that the group size may be relevant when evaluating thermodynamic properties of liquid mixtures. Results on H m E from the Flory model show that orientational effects (i.e., non-random mixing) are rather similar for systems with linear, cyclic or aromatic ketones or alkanals and alkanes. In contrast, orientational effects become weaker in dialkyl carbonate + alkane mixtures. The behavior of 2-Alkanone + 2-Alkanone systems and of mixtures of longer 2-Alkanones or cyclohexanone with dialkyl carbonate is close to random mixing. Larger orientational effects are encountered in solutions of carbonates and shorter 2-Alkanones.
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thermodynamics of amide ketone mixtures 1 volumetric speed of sound and refractive index data for n n dimethylformamide 2 Alkanone systems at several temperatures
The Journal of Chemical Thermodynamics, 2016Co-Authors: Ana Cobos, Fernando . Hevia, Isaías García De La Fuente, J A Gonzalez, Cristina Alonso TristanAbstract:Abstract Densities, ρ, speeds of sound, c, and refractive indices, nD, have been measured for the systems N,N-dimethylformamide (DMF) + propanone, +2-butanone, or +2-pentanone in the temperature range from (293.15 to 303.15) K and at T = 298.15 K for the DMF + 2-heptanone mixture. Due to the high volatility of acetone, the corresponding nD measurements were developed at T = (293.15 and 298.15) K. The direct experimental data were used to determine the excess molar volumes, V m E , and the excess refractive indices, n D E , at the working temperatures. Values of the excess functions at T = 298.15 K, for the speed of sound, cE, the isentropic compressibility, κ S E and for the excess thermal expansion coefficient, α p E , were also calculated. The investigated systems are characterised by strong (amide + ketone) interactions, which become weaker when the Alkanone size is increased. This is supported by negative V m E values; by the dependence on temperature and pressure of V m E , and by positive P int E (excess internal pressure) values. Analysis of the systems in terms of the Rao’s constant indicates that there is no complex formation. In addition, negative V m E values also reveal the existence of structural effects, which largely contribute to the excess molar enthalpy, H m E . V m E and H m E values increase with the chain length of the 2-Alkanone. It allows conclude that the relative V m E variation with the ketone size is closely related to that of the interactional contribution to this excess function. Molar refraction values, Rm, show that dispersive interactions become more relevant for the systems including longer 2-Alkanones.
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thermodynamics of ketone amine mixtures part x excess molar enthalpies at 298 15k for n n n triethylamine 2 Alkanone systems characterization of tertiary amine 2 Alkanone and of amino ketone n alkane mixtures in terms of disquac
Fluid Phase Equilibria, 2013Co-Authors: J A Gonzalez, Isaías García De La Fuente, Ivan Alonso, Jose Carlos CobosAbstract:Abstract Molar excess enthalpies, H m E , at 298.15 K and 0.1 MPa have been measured using a Tian–Calvet microcalorimeter for N,N,N-triethylamine (TEA) + 2-Alkanone mixtures. These data have been used to determine ΔHN-CO, the enthalpy of the amine-ketone interaction, which is practically independent of the ketone size. This allows explain the observed H m E decrease when the ketone size is increased in terms of a lower positive contribution to H m E from the breaking of the Alkanone-Alkanone interactions. Inspection of molar excess volumes and of molar excess internal energies at constant volume (determined in this work) reveals the existence of structural effects, which are more important for mixtures with 2-heptanone. Tertiary alkyl amine + 2-Alkanone, and amino-ketone + n-alkane mixtures have been treated in terms of DISQUAC. The interaction parameters for the carbonyl/amine contacts are reported. It is shown that such contacts are essentially dispersive. Proximity effects in amino-ketone mixtures lead to increased dispersive parameters in comparison to those of amine + ketone solutions. Steric effects related to the length of the alkyl chains attached to the N atom lead to decreased dispersive parameters. DISQUAC describes accurately vapour–liquid equilibria (VLE) and H m E of the investigated mixtures, which have been also treated using UNIFAC (Dortmund version). UNIFAC predictions compare well with DISQUAC results for TEA mixtures. For amino-ketone systems, UNIFAC calculations largely differ from the experimental results. This reveals that interactions parameters must be modified to take into account proximity effects.
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thermodynamics of ketone amine mixtures part ix excess molar enthalpies at 298 15k for dipropylamine or dibutylamine 2 Alkanone systems and modeling of linear or aromatic amine 2 Alkanone mixtures in terms of disquac and eras
Fluid Phase Equilibria, 2013Co-Authors: J A Gonzalez, Isaías García De La Fuente, Ivan Alonso, Jose Carlos CobosAbstract:Abstract Excess molar enthalpies, H m E , at 298.15 K and atmospheric pressure, have been measured, over the entire mole fraction range, by means of a Tian–Calvet microcalorimeter, for the systems: dipropylamine (DPA), or dibutylamine (DBA) + 2-propanone, + 2-butanone, + 2-pentanone, or + 2-heptanone. These data, together with those available in the literature for aniline or N-methylaniline + 2-Alkanone systems, or for 2-Alkanone, or amine + heptane mixtures have been used to determine ΔHN CO, the enthalpy of the amine–ketone interactions. For solutions with a given aromatic amine, Δ H N CO values are large and decrease with the increasing of the ketone size. The corresponding H m E values are large and negative. Mixtures with DPA or DBA are characterized by much weaker interactions between unlike molecules and ΔHN CO is nearly independent of the ketone. The H m E values are positive and decrease when the chain length of the 2-Alkanone is increased, which has been ascribed to a decreasing positive contribution to H m E from the disruption of the ketone–ketone interactions upon mixing. Excess molar internal energies at constant volume, U Vm E , have been obtained from H m E data using our previous volumetric measurements for the studied mixtures. Similar trends that for H m E are observed. Differences between U Vm E and H m E are about 15% for DPA or DBA solutions and are ranged between 35% and 45% for mixtures with aromatic amines. The excess molar volume, V m E , changes in line with H m E and both magnitudes are usually of the same sign, which reveals that the main contribution to the former is the interactional one. In systems including linear secondary amines, structural effects increase with the chain length of the ketone. Amine + 2-Alkanone systems have been also investigated in terms of the DISQUAC, UNIFAC and ERAS models. DISQUAC and ERAS interaction parameters are reported. As in other many applications, the quasichemical interchange coefficients for l = 1 (Gibbs energy), 3 (heat capacity) remain constant along each homologous series considered. DISQUAC improves meaningfully ERAS results on H m E , while UNIFAC results are slightly better. This suggests that physical interactions are more relevant than those related to association/solvation effects.
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thermodynamics of Alkanone aromatic hydrocarbon mixtures
Fluid Phase Equilibria, 2013Co-Authors: J A Gonzalez, Isaías García De La Fuente, Cristina Alonsotristan, Ivan Alonso, Jose Carlos CobosAbstract:Abstract Linear Alkanone or cyclohexanone + aromatic hydrocarbon mixtures have been studied using DISQUAC and the Kirkwood–Buff formalism. The aromatic compounds considered are: benzene, toluene, 1,4-dimethylbenzene, 1,2,4-trimethylbenzene and ethylbenzene. Vapour–liquid equilibria (VLE), molar excess Gibbs energies, G m E , molar excess enthalpies, H m E , and isobaric molar excess heat capacities, C pm E , of the binary systems studied are well represented by DISQUAC. There is a good agreement between experimental H m E values of related ternary mixtures, and DISQUAC predictions obtained by means of binary interaction parameters only DISQUAC improves very meaningfully UNIFAC results on H m E , C pm E , properties which are closely related to the molecular structure of the mixture components. The enthalpy ( H int CO-S ) of the ketone–aromatic hydrocarbon interactions has been evaluated. These interactions become weaker when the Alkanone size increases in mixtures with a given aromatic hydrocarbon, or when the aliphatic surface of the alkylbenzene is increased in systems with a given ketone. Steric effects are more relevant in 1,4-dimethylbenzene mixtures than in those with ethylbenzene. The application of the Kirkwood–Buff formalism to mixtures including toluene or ethylbenzene shows that orientational effects, related to ketone–ketone interactions, exist in solutions with the shorter 2-Alkanones. Such effects are weakened when the chain length of the 2-Alkanone increases. The opposite behaviour is observed when increasing the aliphatic surface of the alkylbenzene in systems with a given 2-Alkanone. The cyclohexanone + benzene mixture shows a structure close to random mixing.
Jose Carlos Cobos - One of the best experts on this subject based on the ideXlab platform.
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thermodynamics of ketone amine mixtures part x excess molar enthalpies at 298 15k for n n n triethylamine 2 Alkanone systems characterization of tertiary amine 2 Alkanone and of amino ketone n alkane mixtures in terms of disquac
Fluid Phase Equilibria, 2013Co-Authors: J A Gonzalez, Isaías García De La Fuente, Ivan Alonso, Jose Carlos CobosAbstract:Abstract Molar excess enthalpies, H m E , at 298.15 K and 0.1 MPa have been measured using a Tian–Calvet microcalorimeter for N,N,N-triethylamine (TEA) + 2-Alkanone mixtures. These data have been used to determine ΔHN-CO, the enthalpy of the amine-ketone interaction, which is practically independent of the ketone size. This allows explain the observed H m E decrease when the ketone size is increased in terms of a lower positive contribution to H m E from the breaking of the Alkanone-Alkanone interactions. Inspection of molar excess volumes and of molar excess internal energies at constant volume (determined in this work) reveals the existence of structural effects, which are more important for mixtures with 2-heptanone. Tertiary alkyl amine + 2-Alkanone, and amino-ketone + n-alkane mixtures have been treated in terms of DISQUAC. The interaction parameters for the carbonyl/amine contacts are reported. It is shown that such contacts are essentially dispersive. Proximity effects in amino-ketone mixtures lead to increased dispersive parameters in comparison to those of amine + ketone solutions. Steric effects related to the length of the alkyl chains attached to the N atom lead to decreased dispersive parameters. DISQUAC describes accurately vapour–liquid equilibria (VLE) and H m E of the investigated mixtures, which have been also treated using UNIFAC (Dortmund version). UNIFAC predictions compare well with DISQUAC results for TEA mixtures. For amino-ketone systems, UNIFAC calculations largely differ from the experimental results. This reveals that interactions parameters must be modified to take into account proximity effects.
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thermodynamics of ketone amine mixtures part ix excess molar enthalpies at 298 15k for dipropylamine or dibutylamine 2 Alkanone systems and modeling of linear or aromatic amine 2 Alkanone mixtures in terms of disquac and eras
Fluid Phase Equilibria, 2013Co-Authors: J A Gonzalez, Isaías García De La Fuente, Ivan Alonso, Jose Carlos CobosAbstract:Abstract Excess molar enthalpies, H m E , at 298.15 K and atmospheric pressure, have been measured, over the entire mole fraction range, by means of a Tian–Calvet microcalorimeter, for the systems: dipropylamine (DPA), or dibutylamine (DBA) + 2-propanone, + 2-butanone, + 2-pentanone, or + 2-heptanone. These data, together with those available in the literature for aniline or N-methylaniline + 2-Alkanone systems, or for 2-Alkanone, or amine + heptane mixtures have been used to determine ΔHN CO, the enthalpy of the amine–ketone interactions. For solutions with a given aromatic amine, Δ H N CO values are large and decrease with the increasing of the ketone size. The corresponding H m E values are large and negative. Mixtures with DPA or DBA are characterized by much weaker interactions between unlike molecules and ΔHN CO is nearly independent of the ketone. The H m E values are positive and decrease when the chain length of the 2-Alkanone is increased, which has been ascribed to a decreasing positive contribution to H m E from the disruption of the ketone–ketone interactions upon mixing. Excess molar internal energies at constant volume, U Vm E , have been obtained from H m E data using our previous volumetric measurements for the studied mixtures. Similar trends that for H m E are observed. Differences between U Vm E and H m E are about 15% for DPA or DBA solutions and are ranged between 35% and 45% for mixtures with aromatic amines. The excess molar volume, V m E , changes in line with H m E and both magnitudes are usually of the same sign, which reveals that the main contribution to the former is the interactional one. In systems including linear secondary amines, structural effects increase with the chain length of the ketone. Amine + 2-Alkanone systems have been also investigated in terms of the DISQUAC, UNIFAC and ERAS models. DISQUAC and ERAS interaction parameters are reported. As in other many applications, the quasichemical interchange coefficients for l = 1 (Gibbs energy), 3 (heat capacity) remain constant along each homologous series considered. DISQUAC improves meaningfully ERAS results on H m E , while UNIFAC results are slightly better. This suggests that physical interactions are more relevant than those related to association/solvation effects.
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thermodynamics of Alkanone aromatic hydrocarbon mixtures
Fluid Phase Equilibria, 2013Co-Authors: J A Gonzalez, Isaías García De La Fuente, Cristina Alonsotristan, Ivan Alonso, Jose Carlos CobosAbstract:Abstract Linear Alkanone or cyclohexanone + aromatic hydrocarbon mixtures have been studied using DISQUAC and the Kirkwood–Buff formalism. The aromatic compounds considered are: benzene, toluene, 1,4-dimethylbenzene, 1,2,4-trimethylbenzene and ethylbenzene. Vapour–liquid equilibria (VLE), molar excess Gibbs energies, G m E , molar excess enthalpies, H m E , and isobaric molar excess heat capacities, C pm E , of the binary systems studied are well represented by DISQUAC. There is a good agreement between experimental H m E values of related ternary mixtures, and DISQUAC predictions obtained by means of binary interaction parameters only DISQUAC improves very meaningfully UNIFAC results on H m E , C pm E , properties which are closely related to the molecular structure of the mixture components. The enthalpy ( H int CO-S ) of the ketone–aromatic hydrocarbon interactions has been evaluated. These interactions become weaker when the Alkanone size increases in mixtures with a given aromatic hydrocarbon, or when the aliphatic surface of the alkylbenzene is increased in systems with a given ketone. Steric effects are more relevant in 1,4-dimethylbenzene mixtures than in those with ethylbenzene. The application of the Kirkwood–Buff formalism to mixtures including toluene or ethylbenzene shows that orientational effects, related to ketone–ketone interactions, exist in solutions with the shorter 2-Alkanones. Such effects are weakened when the chain length of the 2-Alkanone increases. The opposite behaviour is observed when increasing the aliphatic surface of the alkylbenzene in systems with a given 2-Alkanone. The cyclohexanone + benzene mixture shows a structure close to random mixing.
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Orientational Effects and Random Mixing in 1-Alkanol + Alkanone Mixtures
'American Chemical Society (ACS)', 2013Co-Authors: González, Juan Antonio, Alonso Tristán Cristina, García De La Fuente, Isaías ., Jose Carlos Cobos, Ángela . Mediavilla, Riesco NicolásAbstract:1-Alkanol + Alkanone systems have been investigated through the data analysis of molar excess functions, enthalpies, isobaric heat capacities, volumes and entropies, and using the Flory model and the formalism of the concentrationconcentration structure factor (SCC(0)). The enthalpy of the hydroxyl-carbonyl interactions has been evaluated. These interactions are stronger in mixtures with shorter alcohols (methanol-1-butanol) and 2-propanone or 2-butanone. However, effects related to the self-association of alcohols and to solvation between unlike molecules are of minor importance when compared with those which arise from dipolar interactions. Physical interactions are more relevant in mixtures with longer 1-alkanols. The studied systems are characterized by large structural effects. The variation of the molar excess enthalpy with the alcohol size along systems with a given ketone or with the Alkanone size in solutions with a given alcohol are discussed in terms of the different contributions to this excess function. Mixtures with methanol show rather large orientational effects. The random mixing hypothesis is attained to a large extent for mixtures with 1-alkanols ≠ methanol and 2-Alkanones. Steric effects and cyclization lead to stronger orientational effects in mixtures with 3-pentanone, 4-heptanone, or cyclohexanone. The increase of temperature weakens orientational effects. Results from SCC(0) calculations show that homocoordination is predominant and support conclusions obtained from the Flory model.Ministerio de Ciencia e Innovación, under Project FIS2010-1695
J A Gonzalez - One of the best experts on this subject based on the ideXlab platform.
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thermodynamics of amide ketone mixtures 1 volumetric speed of sound and refractive index data for n n dimethylformamide 2 Alkanone systems at several temperatures
The Journal of Chemical Thermodynamics, 2016Co-Authors: Ana Cobos, Fernando . Hevia, Isaías García De La Fuente, J A Gonzalez, Cristina Alonso TristanAbstract:Abstract Densities, ρ, speeds of sound, c, and refractive indices, nD, have been measured for the systems N,N-dimethylformamide (DMF) + propanone, +2-butanone, or +2-pentanone in the temperature range from (293.15 to 303.15) K and at T = 298.15 K for the DMF + 2-heptanone mixture. Due to the high volatility of acetone, the corresponding nD measurements were developed at T = (293.15 and 298.15) K. The direct experimental data were used to determine the excess molar volumes, V m E , and the excess refractive indices, n D E , at the working temperatures. Values of the excess functions at T = 298.15 K, for the speed of sound, cE, the isentropic compressibility, κ S E and for the excess thermal expansion coefficient, α p E , were also calculated. The investigated systems are characterised by strong (amide + ketone) interactions, which become weaker when the Alkanone size is increased. This is supported by negative V m E values; by the dependence on temperature and pressure of V m E , and by positive P int E (excess internal pressure) values. Analysis of the systems in terms of the Rao’s constant indicates that there is no complex formation. In addition, negative V m E values also reveal the existence of structural effects, which largely contribute to the excess molar enthalpy, H m E . V m E and H m E values increase with the chain length of the 2-Alkanone. It allows conclude that the relative V m E variation with the ketone size is closely related to that of the interactional contribution to this excess function. Molar refraction values, Rm, show that dispersive interactions become more relevant for the systems including longer 2-Alkanones.
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thermodynamics of ketone amine mixtures part x excess molar enthalpies at 298 15k for n n n triethylamine 2 Alkanone systems characterization of tertiary amine 2 Alkanone and of amino ketone n alkane mixtures in terms of disquac
Fluid Phase Equilibria, 2013Co-Authors: J A Gonzalez, Isaías García De La Fuente, Ivan Alonso, Jose Carlos CobosAbstract:Abstract Molar excess enthalpies, H m E , at 298.15 K and 0.1 MPa have been measured using a Tian–Calvet microcalorimeter for N,N,N-triethylamine (TEA) + 2-Alkanone mixtures. These data have been used to determine ΔHN-CO, the enthalpy of the amine-ketone interaction, which is practically independent of the ketone size. This allows explain the observed H m E decrease when the ketone size is increased in terms of a lower positive contribution to H m E from the breaking of the Alkanone-Alkanone interactions. Inspection of molar excess volumes and of molar excess internal energies at constant volume (determined in this work) reveals the existence of structural effects, which are more important for mixtures with 2-heptanone. Tertiary alkyl amine + 2-Alkanone, and amino-ketone + n-alkane mixtures have been treated in terms of DISQUAC. The interaction parameters for the carbonyl/amine contacts are reported. It is shown that such contacts are essentially dispersive. Proximity effects in amino-ketone mixtures lead to increased dispersive parameters in comparison to those of amine + ketone solutions. Steric effects related to the length of the alkyl chains attached to the N atom lead to decreased dispersive parameters. DISQUAC describes accurately vapour–liquid equilibria (VLE) and H m E of the investigated mixtures, which have been also treated using UNIFAC (Dortmund version). UNIFAC predictions compare well with DISQUAC results for TEA mixtures. For amino-ketone systems, UNIFAC calculations largely differ from the experimental results. This reveals that interactions parameters must be modified to take into account proximity effects.
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thermodynamics of ketone amine mixtures part ix excess molar enthalpies at 298 15k for dipropylamine or dibutylamine 2 Alkanone systems and modeling of linear or aromatic amine 2 Alkanone mixtures in terms of disquac and eras
Fluid Phase Equilibria, 2013Co-Authors: J A Gonzalez, Isaías García De La Fuente, Ivan Alonso, Jose Carlos CobosAbstract:Abstract Excess molar enthalpies, H m E , at 298.15 K and atmospheric pressure, have been measured, over the entire mole fraction range, by means of a Tian–Calvet microcalorimeter, for the systems: dipropylamine (DPA), or dibutylamine (DBA) + 2-propanone, + 2-butanone, + 2-pentanone, or + 2-heptanone. These data, together with those available in the literature for aniline or N-methylaniline + 2-Alkanone systems, or for 2-Alkanone, or amine + heptane mixtures have been used to determine ΔHN CO, the enthalpy of the amine–ketone interactions. For solutions with a given aromatic amine, Δ H N CO values are large and decrease with the increasing of the ketone size. The corresponding H m E values are large and negative. Mixtures with DPA or DBA are characterized by much weaker interactions between unlike molecules and ΔHN CO is nearly independent of the ketone. The H m E values are positive and decrease when the chain length of the 2-Alkanone is increased, which has been ascribed to a decreasing positive contribution to H m E from the disruption of the ketone–ketone interactions upon mixing. Excess molar internal energies at constant volume, U Vm E , have been obtained from H m E data using our previous volumetric measurements for the studied mixtures. Similar trends that for H m E are observed. Differences between U Vm E and H m E are about 15% for DPA or DBA solutions and are ranged between 35% and 45% for mixtures with aromatic amines. The excess molar volume, V m E , changes in line with H m E and both magnitudes are usually of the same sign, which reveals that the main contribution to the former is the interactional one. In systems including linear secondary amines, structural effects increase with the chain length of the ketone. Amine + 2-Alkanone systems have been also investigated in terms of the DISQUAC, UNIFAC and ERAS models. DISQUAC and ERAS interaction parameters are reported. As in other many applications, the quasichemical interchange coefficients for l = 1 (Gibbs energy), 3 (heat capacity) remain constant along each homologous series considered. DISQUAC improves meaningfully ERAS results on H m E , while UNIFAC results are slightly better. This suggests that physical interactions are more relevant than those related to association/solvation effects.
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thermodynamics of Alkanone aromatic hydrocarbon mixtures
Fluid Phase Equilibria, 2013Co-Authors: J A Gonzalez, Isaías García De La Fuente, Cristina Alonsotristan, Ivan Alonso, Jose Carlos CobosAbstract:Abstract Linear Alkanone or cyclohexanone + aromatic hydrocarbon mixtures have been studied using DISQUAC and the Kirkwood–Buff formalism. The aromatic compounds considered are: benzene, toluene, 1,4-dimethylbenzene, 1,2,4-trimethylbenzene and ethylbenzene. Vapour–liquid equilibria (VLE), molar excess Gibbs energies, G m E , molar excess enthalpies, H m E , and isobaric molar excess heat capacities, C pm E , of the binary systems studied are well represented by DISQUAC. There is a good agreement between experimental H m E values of related ternary mixtures, and DISQUAC predictions obtained by means of binary interaction parameters only DISQUAC improves very meaningfully UNIFAC results on H m E , C pm E , properties which are closely related to the molecular structure of the mixture components. The enthalpy ( H int CO-S ) of the ketone–aromatic hydrocarbon interactions has been evaluated. These interactions become weaker when the Alkanone size increases in mixtures with a given aromatic hydrocarbon, or when the aliphatic surface of the alkylbenzene is increased in systems with a given ketone. Steric effects are more relevant in 1,4-dimethylbenzene mixtures than in those with ethylbenzene. The application of the Kirkwood–Buff formalism to mixtures including toluene or ethylbenzene shows that orientational effects, related to ketone–ketone interactions, exist in solutions with the shorter 2-Alkanones. Such effects are weakened when the chain length of the 2-Alkanone increases. The opposite behaviour is observed when increasing the aliphatic surface of the alkylbenzene in systems with a given 2-Alkanone. The cyclohexanone + benzene mixture shows a structure close to random mixing.
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Orientational effects in Alkanone, alkanal or dialkyl carbonate + alkane mixtures and in Alkanone + Alkanone or + dialkyl carbonate systems
Elsevier, 2017Co-Authors: Fernando . Hevia, Juan Antonio . González, Alonso Tristán Cristina, García De La Fuente, Isaías ., Luis Felipe . SanzAbstract:Interactions and structure of Alkanone, or alkanal or dialkyl carbonate + alkane mixtures, or of 2-Alkanone + 2-Alkanone, or of ketone + dialkyl carbonate systems have been investigated by means of a set of thermodynamic properties and by the application of the Flory model. The properties considered are excess molar quantities: enthalpies, HmE, volumes, VmE, or isobaric heat capacities, CpmE, and liquid-liquid equilibria. Experimental data show that alkane mixtures are characterized by rather strong dipolar interactions. In the case of systems containing ketones with the same number of C atoms and a given alkane, dipolar interactions become weaker in the sequence: aromatic > cyclic > linear. In addition, the mentioned interactions become also weaker in the order: dialkyl carbonate > linear Alkanone > linear alkanal. This is an important result, as carbonates show lower effective dipole moments than the other compounds, and it suggests that the group size may be relevant when evaluating thermodynamic properties of liquid mixtures. Results on HmE from the Flory model show that orientational effects (i.e., non-random mixing) are rather similar for systems with linear, cyclic or aromatic ketones or alkanals and alkanes. In contrast, orientational effects become weaker in dialkyl carbonate + alkane mixtures. The behavior of 2-Alkanone + 2-Alkanone systems and of mixtures of longer 2-Alkanones or cyclohexanone with dialkyl carbonate is close to random mixing. Larger orientational effects are encountered in solutions of carbonates and shorter 2-Alkanones.Consejería de Educación y Cultura of Junta de Castilla y León, under Project BU034U16
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orientational effects in Alkanone alkanal or dialkyl carbonate alkane mixtures and in Alkanone Alkanone or dialkyl carbonate systems
Journal of Molecular Liquids, 2017Co-Authors: Fernando . Hevia, Juan Antonio . González, Isaías García De La Fuente, Cristina Alonsotristan, Luis Felipe . SanzAbstract:Abstract Interactions and structure of Alkanone, or alkanal or dialkyl carbonate + alkane mixtures, or of 2-Alkanone + 2-Alkanone, or of ketone + dialkyl carbonate systems have been investigated by means of a set of thermodynamic properties and by the application of the Flory model. The properties considered are excess molar quantities: enthalpies, H m E , volumes, V m E , or isobaric heat capacities, C pm E , and liquid-liquid equilibria. Experimental data show that alkane mixtures are characterized by rather strong dipolar interactions. In the case of systems containing ketones with the same number of C atoms and a given alkane, dipolar interactions become weaker in the sequence: aromatic > cyclic > linear. In addition, the mentioned interactions become also weaker in the order: dialkyl carbonate > linear Alkanone > linear alkanal. This is an important result, as carbonates show lower effective dipole moments than the other compounds, and it suggests that the group size may be relevant when evaluating thermodynamic properties of liquid mixtures. Results on H m E from the Flory model show that orientational effects (i.e., non-random mixing) are rather similar for systems with linear, cyclic or aromatic ketones or alkanals and alkanes. In contrast, orientational effects become weaker in dialkyl carbonate + alkane mixtures. The behavior of 2-Alkanone + 2-Alkanone systems and of mixtures of longer 2-Alkanones or cyclohexanone with dialkyl carbonate is close to random mixing. Larger orientational effects are encountered in solutions of carbonates and shorter 2-Alkanones.
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thermodynamics of amide ketone mixtures 1 volumetric speed of sound and refractive index data for n n dimethylformamide 2 Alkanone systems at several temperatures
The Journal of Chemical Thermodynamics, 2016Co-Authors: Ana Cobos, Fernando . Hevia, Isaías García De La Fuente, J A Gonzalez, Cristina Alonso TristanAbstract:Abstract Densities, ρ, speeds of sound, c, and refractive indices, nD, have been measured for the systems N,N-dimethylformamide (DMF) + propanone, +2-butanone, or +2-pentanone in the temperature range from (293.15 to 303.15) K and at T = 298.15 K for the DMF + 2-heptanone mixture. Due to the high volatility of acetone, the corresponding nD measurements were developed at T = (293.15 and 298.15) K. The direct experimental data were used to determine the excess molar volumes, V m E , and the excess refractive indices, n D E , at the working temperatures. Values of the excess functions at T = 298.15 K, for the speed of sound, cE, the isentropic compressibility, κ S E and for the excess thermal expansion coefficient, α p E , were also calculated. The investigated systems are characterised by strong (amide + ketone) interactions, which become weaker when the Alkanone size is increased. This is supported by negative V m E values; by the dependence on temperature and pressure of V m E , and by positive P int E (excess internal pressure) values. Analysis of the systems in terms of the Rao’s constant indicates that there is no complex formation. In addition, negative V m E values also reveal the existence of structural effects, which largely contribute to the excess molar enthalpy, H m E . V m E and H m E values increase with the chain length of the 2-Alkanone. It allows conclude that the relative V m E variation with the ketone size is closely related to that of the interactional contribution to this excess function. Molar refraction values, Rm, show that dispersive interactions become more relevant for the systems including longer 2-Alkanones.