Complexes of halloysite with organic compounds

AbstractMore than twenty new organic complexes of halloysite have been prepared and one hundred and twenty-seven compounds were tested. Results are compared with those of earlier studies and use is made of recent findings concerning particle morphology and interstratification effects to interpret the results. The compounds which form complexes with halloysite are polar, and are usually either acids or bases. Their molecules usually contain two functional groups (preferably —OH and/or —NH2), are relatively small and have one functional group per two carbon atoms, but do not usually include cyclic or aromatic types. The best explanation of the existence of these metastable complexes seems to lie in the ability of some organic molecules to form hydrogen bonds with the halloysite structure, about which insufficient knowledge is available to allow quantitative evaluations to be made.

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Synthesis of Monofunctionalized Calix[5]arenes

Synthesis ◽

10.1055/s-0036-1589127 ◽

2017 ◽

Vol 50 (03) ◽

pp. 676-684 ◽

Cited By ~ 3

Author(s):

Arne Lützen ◽

Björn Ingenfeld ◽

Steffen Straub ◽

Christopher Frömbgen

Keyword(s):

Hydrogen Bonds ◽

Functional Groups ◽

Functional Group ◽

Building Blocks ◽

Cone Conformation ◽

Oh Groups ◽

Tert Butyl ◽

Fragment Condensation ◽

Molecular Architectures ◽

Phenolic Oh Groups

Seven OH-free and O-permethylated monofunctionalized calix[5]arenes carrying either additional methyl or tert-butyl groups are prepared following fragment condensation protocols. This strategy proves to be superior to previous approaches. Calix[5]arenes with free OH groups all adopt a cone conformation stabilized by a seam of hydrogen bonds at the lower rim. Post-condensation modifications, i.e., methylation of phenolic OH groups or functional group interconversions can also be achieved. Bulky tert-butyl groups are also found to stabilize the cone conformations of O-methylated compounds. These compounds offer versatile functional groups that make these concave molecules interesting building blocks for the synthesis of more sophisticated molecular architectures.

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Advances in C(sp3)–H Bond Functionalization via Radical Processes

Synthesis ◽

10.1055/s-0039-1690674 ◽

2019 ◽

Vol 51 (24) ◽

pp. 4531-4548 ◽

Cited By ~ 2

Author(s):

Tong Zhang ◽

Yue-Hua Wu ◽

Nai-Xing Wang ◽

Yalan Xing

Keyword(s):

Free Radicals ◽

Hydrogen Atom ◽

Functional Groups ◽

Organic Molecules ◽

Functional Group ◽

Hydrogen Atom Transfer ◽

Significant Progress ◽

Bond Functionalization ◽

Direct Functionalization ◽

Radical Processes

C(sp3)–H Bonds are the most common structures in organic molecules. In recent years, the direct functionalization of C(sp3)–H bonds has attracted wide attention and made significant progress. This review mainly focuses on C(sp3)–H bond functionalization of alkanes with or without functional groups via radical processes reported since 2017. In particular, three methods of generating free radicals are discussed: the use of a radical initiator such as TBHP or DTBP; photocatalysis, and via 1,5-hydrogen atom transfer (1,5-HAT).1 Introduction2 C(sp3)–H Bond Functionalization of Alkanes3 C(sp3)–H Bond Functionalization of Alkanes with a Functional Group4 Conclusions

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Improved AIOMFAC model parameterisation of the temperature dependence of activity coefficients for aqueous organic mixtures

Atmospheric Chemistry and Physics ◽

10.5194/acp-15-447-2015 ◽

2015 ◽

Vol 15 (1) ◽

pp. 447-493 ◽

Cited By ~ 25

Author(s):

G. Ganbavale ◽

A. Zuend ◽

C. Marcolli ◽

T. Peter

Keyword(s):

Experimental Data ◽

Temperature Dependence ◽

Functional Groups ◽

Organic Compounds ◽

Activity Coefficients ◽

Low Temperatures ◽

Functional Group ◽

Organic Mixtures ◽

Organic Functional Groups ◽

Organic Solutions

Abstract. This study presents a new, improved parameterisation of the temperature dependence of activity coefficients in the AIOMFAC (Aerosol Inorganic–Organic Mixtures Functional groups Activity Coefficients) model applicable for aqueous as well as water-free organic solutions. For electrolyte-free organic and organic–water mixtures the AIOMFAC model uses a group-contribution approach based on UNIFAC (UNIversal quasi-chemical Functional-group Activity Coefficients). This group-contribution approach explicitly accounts for interactions among organic functional groups and between organic functional groups and water. The previous AIOMFAC version uses a simple parameterisation of the temperature dependence of activity coefficients, aimed to be applicable in the temperature range from ~ 275 to ~ 400 K. With the goal to improve the description of a wide variety of organic compounds found in atmospheric aerosols, we extend the AIOMFAC parameterisation for the functional groups carboxyl, hydroxyl, ketone, aldehyde, ether, ester, alkyl, aromatic carbon-alcohol, and aromatic hydrocarbon to atmospherically relevant low temperatures. To this end we introduce a new parameterisation for the temperature dependence. The improved temperature dependence parameterisation is derived from classical thermodynamic theory by describing effects from changes in molar enthalpy and heat capacity of a multi-component system. Thermodynamic equilibrium data of aqueous organic and water-free organic mixtures from the literature are carefully assessed and complemented with new measurements to establish a comprehensive database, covering a wide temperature range (~ 190 to ~ 440 K) for many of the functional group combinations considered. Different experimental data types and their processing for the estimation of AIOMFAC model parameters are discussed. The new AIOMFAC parameterisation for the temperature dependence of activity coefficients from low to high temperatures shows an overall improvement of 28% in comparison to the previous model version, when both versions are compared to our database of experimentally determined activity coefficients and related thermodynamic data. When comparing the previous and new AIOMFAC model parameterisations to the subsets of experimental data with all temperatures below 274 K or all temperatures above 322 K (i.e. outside a 25 K margin of the reference temperature of 298 K), applying the new parameterisation leads to 37% improvement in each of the two temperature ranges considered. The new parameterisation of AIOMFAC agrees well with a large number of experimental data sets. Larger model–measurement discrepancies were found particularly for some of the systems containing multi-functional organic compounds. The affected systems were typically also poorly represented at room temperature and further improvements will be necessary to achieve better performance of AIOMFAC in these cases (assuming the experimental data are reliable). The performance of the AIOMFAC parameterisation is typically better for systems containing relatively small organic compounds and larger deviations may occur in mixtures where molecules of high structural complexity such as highly oxygenated compounds or molecules of high molecular mass (e.g. oligomers) prevail. Nevertheless, the new parameterisation enables the calculation of activity coefficients for a wide variety of different aqueous/water-free organic solutions down to the low temperatures present in the upper troposphere.

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The effect of adding hydroxyl functional groups and increasing molar mass on the viscosity of organics relevant to secondary organic aerosols

10.5194/acp-2016-672 ◽

2016 ◽

Cited By ~ 2

Author(s):

James W. Grayson ◽

Mijung Song ◽

Erin Evoy ◽

Mary Alice Upshur ◽

Marzieh Ebrahimi ◽

...

Keyword(s):

Linear Relationship ◽

Functional Groups ◽

Organic Molecules ◽

Molar Mass ◽

Functional Group ◽

Structure Property ◽

Carbon Backbone ◽

Structure Property Relationship ◽

Experimental Values ◽

The Relationship

Abstract. In the following we determine the viscosity of four polyols (2-methyl-1,4-butanediol, 1,2,3-butanetriol, 2-methyl-1,2,3,4-butanetetrol, and 1,2,3,4-butanetetrol) and three saccharides (glucose, raffinose and maltohexaose) mixed with water. The polyol studies were carried out to quantify the relationship between viscosity and the number of hydroxyl (OH) functional groups in organic molecules, whilst the saccharide studies were carried out to quantify the relationship between viscosity and molar mass for highly oxidised organic molecules. Each of the polyols was of viscosity less than or equal to ≤ 6.5e2 Pa s, and a linear relationship was observed between log10 (viscosity) and the number of OH functional groups (R2 ≥ 0.99) for several carbon backbones. The linear relationship suggests that viscosity increases by 1–2 orders of magnitude with the addition of an OH functional group to a carbon backbone. For saccharide-water particles, studies at 28 % RH show an increase in viscosity of 3.6–6.0 orders of magnitude as the molar mass of the saccharide is increased from 180 to 342 g mol−1, and studies at 77–80 % RH, show an increase in viscosity 4.6–6.2 orders of magnitude as molar mass increases from 180 to 991 g mol−1. These results suggest oligomerisation of highly oxidised compounds in atmospheric SOM could lead to large increases in viscosity, and may be at least partially responsible for the high viscosities that are observed in some SOM. Finally, two quantitative structure-property relationship models were used to predict the viscosity of the four polyols studied. The model of Sastri and Rao (1992) was determined to over-predict the viscosity of each of the polyols, with the over-prediction being up to 19 orders of magnitude. The viscosities predicted by the model of Marrero-Morejón and Pardillo-Fontdevila (2000) were much closer to the experimental values, with no values differing by more than 1.3 orders of magnitude.

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Sensitivity of Raman Spectra to Chemical Functional Groups

Applied Spectroscopy ◽

10.1366/000370208786401653 ◽

2008 ◽

Vol 62 (11) ◽

pp. 1221-1225 ◽

Cited By ~ 3

Author(s):

Kevin Judge ◽

Chris W. Brown ◽

Lutz Hamel

Keyword(s):

Functional Groups ◽

Raman Spectra ◽

Organic Molecules ◽

Functional Group ◽

Bayes Theorem ◽

Sensitivity Factor ◽

Spectral Features ◽

Ann Models ◽

Artificial Neural Network Ann ◽

Ketone Ester

Spectral features in Raman spectra of organic molecules can be attributed to certain functional groups. A library of 1222 Raman spectra was used to train an artificial neural network (ANN) for predicting the presence of 13 functional groups. Sensitivity analysis was applied to the ANN models to determine a sensitivity factor or feature spectrum for each functional group. The feature spectra could then be used to predict the presence of specific groups based on Bayes' theorem. Once a model is constructed for each functional group, it can be applied directly to measured spectra of structurally unknown molecules and provide real-time predictions. Prediction accuracies of greater than 90% were obtained for aromatic, alkene, aldehyde, ketone, ester, nitro, and nitrile linkages. Accuracies for alcohols and amines were in the 80% range.

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Hydration Free Energies of Organic Molecules in the FreeSolv Database Calculated with Polarized Atom In Molecules Atomic Charges and the GAFF Force Field.

10.26434/chemrxiv.6015611.v1 ◽

2018 ◽

Author(s):

Maximiliano Riquelme ◽

Alejandro Lara ◽

David L. Mobley ◽

Toon Vestraelen ◽

Adelio R Matamala ◽

...

Keyword(s):

Force Field ◽

Functional Groups ◽

Electrostatic Interactions ◽

Organic Molecules ◽

Force Fields ◽

Chemical Elements ◽

Atomic Charges ◽

Free Energies ◽

Molecular Systems ◽

Solvent Model

<div>Computer simulations of bio-molecular systems often use force fields, which are combinations of simple empirical atom-based functions to describe the molecular interactions. Even though polarizable force fields give a more detailed description of intermolecular interactions, nonpolarizable force fields, developed several decades ago, are often still preferred because of their reduced computation cost. Electrostatic interactions play a major role in bio-molecular systems and are therein described by atomic point charges.</div><div>In this work, we address the performance of different atomic charges to reproduce experimental hydration free energies in the FreeSolv database in combination with the GAFF force field. Atomic charges were calculated by two atoms-in-molecules approaches, Hirshfeld-I and Minimal Basis Iterative Stockholder (MBIS). To account for polarization effects, the charges were derived from the solute's electron density computed with an implicit solvent model and the energy required to polarize the solute was added to the free energy cycle. The calculated hydration free energies were analyzed with an error model, revealing systematic errors associated with specific functional groups or chemical elements. The best agreement with the experimental data is observed for the MBIS atomic charge method, including the solvent polarization, with a root mean square error of 2.0 kcal mol<sup>-1</sup> for the 613 organic molecules studied. The largest deviation was observed for phosphor-containing molecules and the molecules with amide, ester and amine functional groups.</div>

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Adsorption of Vapours of Some Organic Compounds on Surface of Iron-Substituted Layered Vanadyl Phosphate

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc20000047 ◽

2000 ◽

Vol 65 (1) ◽

pp. 47-57 ◽

Cited By ~ 1

Author(s):

Pavel Hradil ◽

Jiří Votinský ◽

Karel Komárek ◽

Vítězslav Zima ◽

Jaroslava Kalousová ◽

...

Keyword(s):

Organic Compounds ◽

Organic Molecules ◽

Ferric Ions ◽

Vanadyl Phosphate ◽

Enthalpy Of Adsorption ◽

Adsorbent Surface ◽

Specific Retention Volumes ◽

Specific Retention ◽

Retention Volumes ◽

Chromatographic Measurement

Gas chromatographic measurement of specific retention volumes of vapours of selected groups of organic compounds has been used to determine differential molar enthalpy of adsorption of their molecules on the surface of layered vanadyl phosphate substituted with ferric ions having the composition of [Fe(H2O)]0.20(VO)0.80PO4. Various types of bonds of the molecules to the surface of the layered adsorbent including their probable orientation with respect to the layers have been discussed. It was observed a dependence of the specific peak elution volume and shape of chromatographic peak on the sample size in the cases of those compounds whose molecules are chemically bound to the adsorbent surface. A connection is pointed out between the adsorption strength of the organic molecules on the layered adsorbent and the tendency of the system to undergo intercalation reaction.

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Non-Enzymatic Desymmetrization Reactions in Aqueous Media

Symmetry ◽

10.3390/sym13040720 ◽

2021 ◽

Vol 13 (4) ◽

pp. 720

Author(s):

Satomi Niwayama

Keyword(s):

Natural Products ◽

Total Synthesis ◽

Functional Groups ◽

Organic Compounds ◽

Recent Progress ◽

Aqueous Media ◽

Building Blocks ◽

Organic Reactions ◽

Environmentally Benign ◽

Enzymatic Desymmetrization

Symmetric organic compounds are generally obtained inexpensively, and therefore they can be attractive building blocks for the total synthesis of various pharmaceuticals and natural products. The drawback is that discriminating the identical functional groups in the symmetric compounds is difficult. Water is the most environmentally benign and inexpensive solvent. However, successful organic reactions in water are rather limited due to the hydrophobicity of organic compounds in general. Therefore, desymmetrization reactions in aqueous media are expected to offer versatile strategies for the synthesis of a variety of significant organic compounds. This review focuses on the recent progress of desymmetrization reactions of symmetric organic compounds in aqueous media without utilizing enzymes.

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Resilience of Epiphytic Lichens to Combined Effects of Increasing Nitrogen and Solar Radiation

Journal of Fungi ◽

10.3390/jof7050333 ◽

2021 ◽

Vol 7 (5) ◽

pp. 333

Author(s):

Lourdes Morillas ◽

Javier Roales ◽

Cristina Cruz ◽

Silvana Munzi

Keyword(s):

Global Change ◽

Solar Radiation ◽

Functional Groups ◽

Physiological Response ◽

Functional Group ◽

Environmental Drivers ◽

Combined Effects ◽

Environmental Stressor ◽

Comprehensive Understanding ◽

Direct Sunlight

Lichens are classified into different functional groups depending on their ecological and physiological response to a given environmental stressor. However, knowledge on lichen response to the synergistic effect of multiple environmental factors is extremely scarce, although vital to get a comprehensive understanding of the effects of global change. We exposed six lichen species belonging to different functional groups to the combined effects of two nitrogen (N) doses and direct sunlight involving both high temperatures and ultraviolet (UV) radiation for 58 days. Irrespective of their functional group, all species showed a homogenous response to N with cumulative, detrimental effects and an inability to recover following sunlight, UV exposure. Moreover, solar radiation made a tolerant species more prone to N pollution’s effects. Our results draw attention to the combined effects of global change and other environmental drivers on canopy defoliation and tree death, with consequences for the protection of ecosystems.

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N′-Cyclododecylidenepyridine-4-carbohydrazide

Acta Crystallographica Section E Structure Reports Online ◽

10.1107/s1600536812011774 ◽

2012 ◽

Vol 68 (4) ◽

pp. o1205-o1205

Author(s):

Andreas Lemmerer ◽

Joel Bernstein ◽

Volker Kahlenberg

Keyword(s):

Crystal Structure ◽

Hydrogen Bonds ◽

Functional Groups ◽

Title Compound ◽

Antituberculosis Drug ◽

Compound C

The title compound, C18H27N3O, is a derivative of the antituberculosis drug isoniazid (systematic name: pyridine-4-carbohydrazidei). The crystal structure consists of repeatingC(4) chains along thebaxis, formed by N—H...O hydrogen bonds with adjacent amide functional groups that are related by ab-glide plane. The cyclododecyl ring has the same approximately `square' conformation, as seen in the parent hydrocarbon cyclododecane.

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