Homologous Series Of Organic Compounds Research Articles

Fluid Components in Cordierite from the Rocks of Epidote-Amphibole Facies of the Muzkol Metamorphic Complex, Tajikistan: Pyrolysis-Free GC-MS Data

The composition of volatile components of cordierite from the Muzkol metamorphic complex was studied using shock destruction with pyrolysis-free gas chromatography-mass spectrometry (GC-MS) with simultaneous IR and Raman spectroscopy. Applying the GC-MS procedure, the component relative concentrations (rel.%) and composition of different zones of cordierite crystals were determined. It was found that the substantially magnesian cordierite was formed with a predominantly aqueous-carbonic acid fluid (from 57.06 to 67.88 rel.% H2O, from 24.29 to 32.95 rel.% CO2). From the center towards the crystal periphery, the molar fraction of carbon dioxide (CO2/(H2O + CO2)) decreases from 0.36 to 0.26, whereas the alkane/alkene ratio increases from 0.80 to 0.88. At least 11 homologous series of organic compounds among the identified volatile components, in addition to water and carbon dioxide, were determined, including oxygen-free aliphatic and cyclic hydrocarbons (paraffins, olefins, cyclic alkanes and alkenes, arenes, polycyclic aromatic hydrocarbons (PAHs)), as well as oxygen-containing (alcohols, esters, aldehydes, ketones, carboxylic acids) and heterocyclic (furans, dioxanes) organic compounds.

Hydrocarbons in Fluid Inclusions from Native Gold, Pyrite, and Quartz of the Sovetskoe Deposit (Yenisei Ridge, Russia) According to Pyrolysis-Free Gas Chromatography-Mass Spectrometry Data

Abstract ––The first results on the composition of fluids from native gold and associated pyrite and quartz have been obtained. Despite the small amount of analytical data, these results are of scientific and practical interest. The identified geochemical criteria can be used for the assessment of gold ore shoots and the substantiation of prospecting in the region. The one-act shock-destructive extraction of volatiles from fluid inclusions and their pyrolysis-free gas chromatography–mass spectrometry analysis made it possible to determine the composition of fluids in native gold and in associated pyrite and quartz. Based on these data, we have first shown that fluids in native gold, pyrite, and quartz are a mineral-forming multicomponent system. In addition to water and carbon dioxide, the studied fluid inclusions contain representatives of at least 11 homologous series of organic compounds, including oxygen-free aliphatic and cyclic hydrocarbons (paraffins, olefins, cyclic alkanes and alkenes, arenes, and polycyclic aromatic hydrocarbons), oxygenated hydrocarbons (alcohols, esters, furans, aldehydes, ketones, and carboxylic acids), and nitrogened, sulfonated, halogenated, and siliconorganic compounds. The portion of hydrocarbons together with S–N–Cl–F–Si compounds reaches 52.0 rel.% in fluid inclusions from native gold, 10.1 rel.% in fluid inclusions from pyrite, and 18.0 rel.% in fluid inclusions from quartz. Gold-transporting gas fluids have reducing properties. Pyrite and quartz contain oxidized water–carbon dioxide fluids with low contents of hydrocarbons and nitrogen–halogenated compounds.

Empirical method for predicting the enthalpy changes of combustion of amides

The enthalpy change of combustion is one of the basic thermochemical characteristics of an organic compound, indicating the amount of heat produced in the complete combustion of the substance. The enthalpy changes of combustion of many organic compounds have been experimentally determined. Hitherto, the existing empirical approaches have aimed at calculating the combustion enthalpy change of individual classes only, which do not always satisfactorily agree with the experimental results. Therefore, the method of correlation?regression analysis is proposed herein to establish the combustion enthalpy changes of previously unexplored compounds. As is known, a linear relationship between two characteristics is possible only if both of them obey the principle of additivity, i.e., in a homologous series of organic compounds with increasing number of CH2-groups, the value of additive characteristic (for example, the enthalpy change of vaporization) should increase by a certain constant amount.

Octanol/water partition coefficients Kow: A critical examination of the value of the methylene group contribution to log Kow for homologous series of organic compounds

The literature data for the values of the octanol/water partition coefficient KOW are examined critically, specifically in relation to the methylene group increment in logKOW – here called the lipicity L – for homologous series. With simply substituted alkanes, the plots of L versus the methylene group number m are linear, following the form: L=α+βm (Collander equation). The slope parameter β represents the methylene group increment, which widely is expected to be constant on the simplest theoretical grounds, and assumed to be so in most practical applications. The Collander equation behaviour for some 84 homologous series and subseries, ranging in complexity from the alkanes up to the alkyladenines and alkyl galactosides, is presented graphically. Compounds with α,ω-disubstituted alkyl chains give nonlinear Collander plots. The remaining series give linear Collander plots, but the methylene group increment β is not constant, the variation being statistically significant, with the distribution essentially normal (Gaussian) and with the mean value β¯=0.52 and standard deviation σ(β)=0.06. The literature data from other solvent/water systems – ethoxyethane (diethyl ether), and the two alkanes heptane and hexadecane – show similar behaviour. Most significantly, the fact that the methylene group increment β is not constant casts doubts on the applicability of the linear free energy approach, and of the “fragmental methods” that are widely used in interpreting and predicting partition coefficients. More generally, the graphical approach used is essential in a proper treatment of correlations of this kind; the graphs form an atlas that shows at a glance the partition coefficient behaviour for these series, revealing anomalies in the literature data that need to be rectified, and gaps that need to be filled.

Comparative Graphs for Boiling Point Curves of Representative Homologous Series

The boiling point curves of 22 representative homologous series of organic compounds are in part approximately presented in a comparative graph. The graph reduces the number of curves by common trendlines and representative curves. Accurate graphs with various selections of the curves are part of the Supporting Information.

Recurrent model of acute toxicity in homologous series of organic compounds

A simple recurrent equation is proposed as a model describing acute toxicity in homologous series of organic compounds in relation to various biological objects. The recurrent model of toxicity provided better extrapolation than linear and parabolic models. Plotting of The coefficients of recurrent equations plotted on planes defined by these coefficients for types of chemical compounds allowed the nonspecific or specific nature of toxicity in homologous series to be identified. Similar visualization in relation to different types of biological objects allowed toxicological relatedness to be identified on the basis of the distances between them. These results may provide grounds for creating computer programs predicting the acute toxicities of new chemical compounds on the basis of QSAR approaches.

Classifications of families of homologous organic compounds based on energy by means of ab initio ­HF, MP2 and DFT optimizations

AbstractA method is suggested for combining the quantum chemical principle of isolated molecules and the systematics of homologous families for different functional groups in traditional organic chemistry. The classification of organic compounds is performed by statistical treatments of fundamental quantum mechanical quantities such as total and partial energies. We used the total energies (computed by DFT BLYP and B3LYP, HF and MP2 methods, which are size‐extensive, applying the 6–31 G** and some other basis sets) of isolated molecules obtained by gradient optimizations to classify homologous series of organic compounds by linear least‐squares regressions versus the total number of electrons. Two numerical parameters, slope (h) and intercept (s), are obtained characterizing each family of homologous compounds. Families of for example 17 different functional groups of the same CH2‐homologous unit are grouped on parallel lines with the same slope h, differing only in their s parameters. Isomeric compounds differ in their s values if they belong to the same homologous unit. Compounds of other homologous units (conjugated alkenes, cumulenes and benzenoides) are found with different slopes h on regression lines. Energy partitioning leads also to linear regressions of different statistical accuracy for the components which add fully to the observed h and s parameters. The h and s parameters allow the prediction of unknown total energies of homologous compounds from total energies of a subset of smaller compounds which belong to the same homologous family. Likewise, atomization energies can be predicted using the derived h and s parameters. Copyright © 2002 John Wiley & Sons, Ltd.

Prediction of retention indices: V. Influence of electronic effects and column polarity on retention index

The retention index increment for addition of a methylene group to an analyte molecule is shown for 1-halo- n-alkanes to be different from 100 i.u., a value that is customarily assigned according to the current convention in retention index prediction. In temperature-programmed gas chromatography using linearly interpolated retention index I, a linear regression equation, I= AZ+(GRF), with the number of atoms ( Z) in the molecule as variable can describe the retention of 16 homologous series of organic compounds on non-polar and polar columns with characteristic A (linear regression coefficient) and (GRF) (group retention factor) values. A molecular model of retention on the basis of electron density and electron density distribution relative to that of n-alkane is proposed. This model brings out the inter- and intramolecular electronic effects in the analyte molecule and its dipole–dipole interaction with the stationary liquid phases, as variations in the A value. The (GRF) value varies with the connectivity ability of a functional group for extended conjugation, substitution, etc., but is most influenced by hydrogen bonding (H-bonding) with the stationary liquid phase. One can estimate the sequence of elution of a mixture of organic compounds from any two of the three parameters on the right-hand side of the above equation or retrieve the retention indexes of an entire homologous series from its A and (GRF) values. The fact that each analyte molecule has its own A value on different columns makes column difference (Δ I) compound-specific rather than column-specific, a departure from previous assumptions.

Comparison of the behaviour of gas-liquid and gas-liquid-solid capillary columns through the determination of thermodynamic characteristics

Interpolation methods, used for the prediction of retention times in programmed temperature capillary gas chromatography, employ equations whose parameters are correlated, through the capacity factor and the phase ratio of the column, with the thermodynamic parameters, that can be calculated by using retention data obtained at various temperatures. Homologous series of organic compounds (linear alkanes and alcohols) were analysed on bonded phase polar, non-polar and carbon layer open tubular columns and the values of some thermodynamic parameters were obtained. Their dependence on the polarity of the liquid phase and of the solutes, film thickness, temperature of the column, was investigated and allowed comparison of the behaviour of the different phases tested.

Theoretical study of the inversion of the alcohol acidity scale in aqueous solution. Toward an interpretation of the acid-base behavior of organic compounds in solution

Some homologous series of organic compounds present an acid-base behavior in solution very different from that in the gas phase. The series formed by MeOH to t-BuOH is a representative example of these series with a gas-phase acidity order (t-BuOH>i-PrOH>EtOH>MeOH) following the greater ability of the methyl group relative to hydrogen to stabilize the charged centers while in solution the final ordering is just the opposite. In this paper, the change in the alcohol's acidity scale when passing from the gas phase to solution is studied. Gas-phase energies are calculated at the MP4 level with the 6-31G * basis set and an sp diffuse function added on the oxygen atom

Ionization energies of homologous organic compounds and correlation with molecular size

AbstractThe empirical relationship IE ∝︁ 1/n, between the ionization energy (IE) and molecular size (as represented by the number of atoms, n) in homologous series of organic compounds has been confirmed for n‐alkanes, alkyl halides, cyclic ethers and alkyl‐subsiituted cycloalkanes. For each series, the plot of IE vs. 1/n produces a line of characteristic slope. The only exception is the cycloalkanes themselves, whose IE values (from C3 to C8) are closely similar. The possible relationship between the IE, the polarizability of the molecules and the energy of the highest occupied molecular orbital is briefly discussed.

New form of correlational dependence of change in lipophilicity in homologous series of organic compounds

New form of correlational dependence of change in lipophilicity in homologous series of organic compounds

Applicability of a universal equation in capillary gc for calculating the retention indexes and boiling points of members of O-, N-, and S-containing homologous series

1. The fundamental character of the universal equation proposed earlier for calculation of retention parameters of homologs in chromatography has been confirmed. It has been shown that the equation can be used with excellent results to calculate the boiling points of members of homologous series of organic compounds. 2. It has been demonstrated, using the example of 18 homologous series of organic compounds (alcohols, alkylamines, sulfides, mercaptans, nitroalkanes, isonitriles) that the equation can be correctly used to predict boiling points.

Principle of nonadditivity of energy contributions to sorption energy and its use for identification in chromatography

1. A nonadditive character is postulated for the change in energy of van der Waals interaction for members of a homologous series of organic compounds. 2. An equation is proposed, taking into account the deviation of free energy from the additivity principle, and making it possible to calculate the retention parameters of homologs, beginning with the first member, in gas and liquid chromatography, including thin-layer chromatography. 3. On the basis of the results obtained, the equation can be considered as universal and can be recommended for use in calculating parameters describing the behavior of homologs of organic substances in liquid-gas, solid-gas, and liquid-liquid systems in which the interaction is due to van der Waals forces.

Violation of the linearity principle of additivity of sorption energy in chromatography. A universal equation describing retention behavior

AbstractDeviations from the additivity of energy contributions to substance sorption energies, determined on the basis of thermodynamic studies of GC behavior of homologous series of organic compounds fall into two categories: one for n‐alkanes, the other for homologous series containing a functional group. A previously derived equation is proposed for homologous series, describing the deviation from the linear dependence of retention parameters with a propagating homolog n‐alkyl chain. The equation permits calculation of retention parameters of homologs starting from the first member in gas‐liquid, gas‐solid, and liquid‐liquid systems. The results prove its universal applicability.

Application of molecular topology to quantitative structure‐biodegradability relationships

AbstractSimple and multiple linear regressions were applied to the development of models for predicting biodegradability of chemicals from molecular connectivity indexes. Indexes were calculated using the program CFUNC, on the DECsystem 10 computer at the National Institutes of Health, Bethesda, Maryland. Biodegradation data from test systems containing natural media or inocula were obtained from the literature for several homologous series of organic compounds; within each series, all compounds had been tested under the same conditions. The following one‐variable models were among those obtained: for 2,4‐D alkyl esters, log rate constant versus 2Xv, r2 = 0.954 (n = 6); for N‐3‐chlorophenylcarbamates, log percent degraded versus 4Xp/c, r2 = 0.971 (n = 7); for dialkyl ethers, log percent theoretical oxygen demand (%ThOD) versus 2Xv, r2 = 0.974 (n = 6); for dialkyl phthalate esters, rate constant versus 2X, r2 = 0.938 (n = 12); for aliphatic acids, %ThOD versus 4Xc, r2 = 0.895 (n = 10). Two‐variable models substantially improved results for aliphatic alcohols and acids. These results indicate that the apparent effect of alkyl chain branching on biodegradability can be quantitatively described by connectivity indexes, especially 2X, 3Xc, 4Xc and 4Xp/c, 3Xp also appeared frequently, especially in two‐variable models, suggesting a possible role for molecular shape as a determinant of biodegradability. The results suggest that molecular topology holds promise for future research in quantitative structure‐biodegradability relationships.

The reason for non-linear variation of specific retention volumes and retention indices for members of homologous series of organic compounds

Universal equations have been obtained for aliphatic homologous series permitting the calcualtion of the specific retention volume, retention index, partial free energy of sorption and the change in the energy contribution of a methylene unit depending on the length of the carbon chain.

THE EFFECT OF SOLUTES ON BUBBLE SIZE IN AIR-WATER DISPERSIONS

Bubble size distributions in a bubble column of 200 mm diameter were measured by means of a photoelectric probe. The gas-liquid dispersion was generated by distributing air with a porous plate into aqueous solutions of electrolytes and of organic compounds (alcohols, glycols, ketones, carboxylic acids, saccharose, carboxymethyl-cellulose, detergents). For all these solutes there exists a rather narrow concentration range in which the change from quick coalescence in pure water to coalescence suppression takes place. Though rough relationships between concentrations for coalescence suppression and molecular properties can be found (ionic strength for electrolytes, number of carbon atoms in a homologous series of organic compounds), exact equations based on a theory of coalescence cannot be given. The bubble size distributions obtained in the experiments have also been used to show the impact of coalescence phenomena on gas-liquid mass transfer. For this purpose, surface areas were calculated from measured gas hold-up and mean bubble diameters (Sauter diameters). A comparison of these data with the trends for volumetric mass transfer coefficients reported in the literature for n-alcohols (C1-C2i) showed good agreement, despite the fact that the mass transfer data had been obtained in a quite different gas-liquid contacting device (stirred vessel).

Inhibition of bubble coalescence by solutes in air/water dispersions

Measurement of bubble size distributions in bubble column by a photoelectric probe showed that both electrolyte and organic solutes affect coalescence behaviour of aqueous solutions drastically within a narrow concentration range, changing from quick coalescence as in pure water to coalescence restraining. Besides the electrolytes NACl, Na 2SO 4, Al 2(SO 4) 3, NaOH, organic compounds from homologous series ( n-alcohols, diols, ketones, carboxylic acids), detergents, saccharose, and carboxymethylcellulose have been used as solutes. Rough relationships between concentrations for coalescence restraining and molecular properties can be given (ionic strength for electrolytes, number of C-atoms in homologous series of organic compounds), but no exact equations based on a theory of coalescence. For the n-alcohols (C 1-C 8), specific surface areas were calculated from experimental mean bubble diameters (Sauter diameters) and measured gas hold-up and compared to volumetric mass transfer coefficients from literature. Concentration dependence of the two types of data showed surprisingly good agreement with regard to the fact that the mass transfer data had been obtained in a gas-liquid contacting device (stirred vessel) quite different to the reactor used in this work (bubble column).

Analysis of the equations which describe the gas-chromatographic behavior of homologous series of organic compounds

1. We have assessed the correlational and extrapolation possibilities of six equations, used in the literature to describe the dependence of corrected retainable volumes 1500 and retention indices on the serial number of the homolog (n), for the case of n-alkanes, secondary and tertiary aliphatic amines, sulfides, aldehydes, and methyl ketones. 2. The correlational possibility of equations which describe the change in retention indices is greater than that of equations which describe the corrected retention volumes. In homologous series, the dependence of GC-retention parameters on n cannot be described by another form of equation. The initial region is described by the nonlinear equation (4) and the subsequent region by a linear equation which can be used to determine the retention index for all homologs for which n ≥ 8 with reasonable accuracy. Both equations can be used for the GC identification of substances with the aid of a calculator.