Enthalpies of transfer of aromatic molecules from the vapor state to polar and nonpolar solvents

1974 ◽  
Vol 96 (14) ◽  
pp. 4705-4706 ◽  
Author(s):  
R. Fuchs ◽  
T. M. Young ◽  
R. F. Rodewald
Keyword(s):  
Enthalpies Of Transfer ◽  
Vapor State ◽  
Aromatic Molecules ◽  
Nonpolar Solvents

A SPECTROSCOPIC STUDY OF HYDROGEN BONDING IN PERFORMIC AND PERACETIC ACIDS

1952 ◽  
Vol 30 (11) ◽  
pp. 821-830 ◽  
Author(s):  
Paul A. Giguère ◽  
A. Weingartshofer Olmos
Keyword(s):  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Spectroscopic Study ◽  
Infrared Spectra ◽  
Peracetic Acid ◽  
The Other ◽  
Frequency Shifts ◽  
Vapor State ◽  
Nonpolar Solvents ◽  
Intramolecular Hydrogen

The infrared spectra of concentrated performic and peracetic acids were measured in the rock-salt region. The most significant features are theO—H stretching frequency at 3310–3350 cm−1 and the OH bending frequency at 1450 cm−1 which, for both peracids, remain essentially the same in the vapor state as in the liquid or in solution in nonpolar solvents. This is attributed to intramolecular hydrogen bonds resulting in particularly stable five-membered rings,[Formula: see text]Steric conditions in the percarboxylic group are favourable to such ring formation or chelation. From the observed frequency shifts the energy of these hydrogen bonds is estimated to be about 7 kcal. per mole. No evidence for unchelated molecules was found even in very dilute solutions of peracetic acid in nonpolar solvent nor in the vapour at low pressure and moderate temperature. Tentative assignments of the other frequencies in the spectra of the peracids are made by comparison with those of formic and acetic acids.The danger involved in handling these peracids in concentrated form is emphasized.

Infrared Analysis of Ethylene Sulfite and sym-Dimethylethylene Sulfite

1970 ◽  
Vol 24 (5) ◽  
pp. 492-495 ◽  
Author(s):  
Kenneth L. Dorris
Keyword(s):  
Ir Spectra ◽  
Infrared Spectra ◽  
Far Infrared ◽  
Dimethyl Sulphoxide ◽  
Infrared Analysis ◽  
Liquid Form ◽  
Vapor State ◽  
Nonpolar Solvents ◽  
Ethylene Sulfite ◽  
Far Infrared Spectra

The ir spectra of ethylene and sym-dimethylethylene sulfite in the vapor, and dilute solutions in polar and nonpolar solvents have been recorded from 400 to 4000 cm−1. In addition, the far infrared spectra of these compounds have been recorded to 33 cm−1. In the liquid form, an equilibrium between two S = O conformations exists, while in the vapor state, only one conformer is observed. The S = O dipole in these sulfites is more sensitive to solvent than normal ketones and diphenyl sulphoxide and less dependent than dimethyl sulphoxide.

Enthalpies of interaction of nonpolar solutes with nonpolar solvents. The role of solute polarizability and molar volume in solvation

1987 ◽  
Vol 65 (11) ◽  
pp. 2624-2627 ◽  
Author(s):  
Richard Fuchs ◽  
Eric J. Chambers ◽  
W. Kirk Stephenson
Keyword(s):  
Carbon Tetrachloride ◽  
Molar Volume ◽  
Correlation Coefficients ◽  
Molar Refraction ◽  
Cavity Formation ◽  
Enthalpies Of Transfer ◽  
Nonpolar Solvents ◽  
Formation Enthalpies ◽  
Solute Interaction

Heats of solution of 10 nonpolar solutes (carbon tetrachloride, perfluoroheptane, diiodomethane, benzene, hexane, decane, hexadecane, cyclohexane, toluene, and mesitylene) in 11 nonpolar solvents (heptane, cyclohexane, carbon tetrachloride, benzene, carbon disulfide, diiodomethane, toluene, mesitylene, tetrachloroethylene, 1,1,2-trichlorotrifluoroethane, and hexadecane) have been combined with solute heats of vaporization to give enthalpies of transfer from vapor to solvent (ΔH(v → S)). The heat of vaporization of diiodomethane has been measured (11.70 ± 0.01 kcal/mol). Correlations of the form ΔH(v → S) = a + bMMR + cMV describe the solvent–solute interaction enthalpies with high precision (correlation coefficients 0.991–0.999). Earlier correlations with only the molar refraction are limited to solutes of similar refractive index. In each solvent ΔH(v → S) becomes more exothermic with an increase in the solute molar refraction term, and less exothermic with an increase in the solute molar volume term. These terms represent solvent–solute dispersion interaction enthalpies, and solvent cavity formation enthalpies, respectively.

Enthalpies of transfer of alkane solutes from the vapor state to organic solvents

1985 ◽  
Vol 63 (2) ◽  
pp. 349-352 ◽  
Author(s):  
Richard Fuchs ◽  
W. Kirk Stephenson
Keyword(s):  
Organic Solvents ◽  
Solubility Parameter ◽  
Empirical Correlation ◽  
Enthalpies Of Transfer ◽  
Vapor State ◽  
Heats Of Solution ◽  
Hildebrand Solubility Parameter

Heats of solution of 5 – 8 C5–C16 alkane liquids have been determined in each of 19 organic solvents covering the Taft–Kamlert π* (dipolarity-polarizability) range −0.08 to 1.00. Enthalpies of alkane transfer from vapor to solvents have been calculated (ΔH(v → S) = ΔHs − ΔHv). The methylene increments in (ΔH(v → S) in the 19 solvents and water (−1.18 to −0.67 kcal/mol) are not well correlated with the Hildebrand solubility parameter δ, but an empirical correlation exists with solvent π* and polarizability:[Formula: see text](n = 20, r = 0.977, see = 0.032). By this criterion the small methylene increment in water appears to be associated with the high dipolarity and low polarizability of water.

Graphene and Graphene Oxide Applications for SERS Sensing and Imaging

2019 ◽  
Vol 26 (38) ◽  
pp. 6878-6895 ◽  
Author(s):  
Anna Jabłońska ◽  
Aleksandra Jaworska ◽  
Mateusz Kasztelan ◽  
Sylwia Berbeć ◽  
Barbara Pałys
Keyword(s):  
Graphene Oxide ◽  
Surface Enhanced Raman Spectroscopy ◽  
Biological Species ◽  
Chemical Mechanism ◽  
Aromatic Molecules ◽  
Sers Enhancement ◽  
Reduced Graphene ◽  
Surface Enhanced Raman ◽  
Active Nanoparticles ◽  
Fluorescence Quencher

: Surface Enhanced Raman Spectroscopy (SERS) has a long history as an ultrasensitive platform for the detection of biological species from small aromatic molecules to complex biological systems as circulating tumor cells. Thanks to unique properties of graphene, the range of SERS applications has largely expanded. Graphene is efficient fluorescence quencher improving quality of Raman spectra. It contributes also to the SERS enhancement factor through the chemical mechanism. In turn, the chemical flexibility of Reduced Graphene Oxide (RGO) enables tunable adsorption of molecules or cells on SERS active surfaces. Graphene oxide composites with SERS active nanoparticles have been also applied for Raman imaging of cells. This review presents a survey of SERS assays employing graphene or RGO emphasizing the improvement of SERS enhancement brought by graphene or RGO. The structure and physical properties of graphene and RGO will be discussed too.

Conformation and electronic structure of aromatic chloroformates

1987 ◽  
Vol 52 (4) ◽  
pp. 970-979 ◽  
Author(s):  
Otto Exner ◽  
Pavel Fiedler
Keyword(s):  
Electronic Structure ◽  
Oxygen Atom ◽  
Strong Interaction ◽  
Electron Distribution ◽  
Room Temperature ◽  
Functional Group ◽  
Dipole Moments ◽  
Carbonyl Oxygen ◽  
Nonpolar Solvents ◽  
Single Method

Aromatic chloroformates Ib-Ie were shown to exist in the ap conformation, in agreement with aliphatic chloroformates, i.e. the alkyl group is situated cis to the carbonyl oxygen atom as it is the case in all esters. While 4-nitrophenyl chloroformate (Ie) is in this conformation in crystal, in solution at most several tenths of percent of the sp conformation may be populated at room temperature and in nonpolar solvents only. A new analysis of dipole moments explained the previous puzzling results and demonstrated the impossibility to determine the conformation by this single method, in consequence of the strong interaction of adjoining bonds. If, however, the ap conformation is once proven, the dipole moments reveal some features of the electron distribution on the functional group, characterized by the enhanced polarity of the C-Cl bond and reduced polarity of the C=O bond. This is in agreement with the observed bond lengths and angles.

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