Infrared Study of 4- and 3-Substituted Anilines in Hexane, Carbon Tetrachloride, or Chloroform (0.5% or Less) Solutions

1992 ◽  
Vol 46 (8) ◽  
pp. 1273-1278 ◽  
Author(s):  
R. A. Nyquist ◽  
D. A. Luoma ◽  
C. W. Puehl
Keyword(s):  
Hydrogen Bonding ◽  
Bond Angle ◽  
Frequency Separation ◽  
Intermolecular Hydrogen Bonding ◽  
Substituted Anilines ◽  
Infrared Study ◽  
Solvent Interaction ◽  
Solute Solvent Interaction ◽  
Cl Atoms ◽  
Ir Bands

As the NH2 bond angle increases, both vasym NH2 and vsym. NH2 increase in frequency, and the frequency separation between vasym. NH2 and vsym. NH2 increases as the Hammett σp and σm values increase (increasing electron withdrawing power). The NH2 bond angles change with solute/solvent interaction. In CHCl3 solution IR bands are observed for two sets of vasym. NH2 and vsym. NH2 frequencies. It is suggested that this is the result of intermolecular hydrogen bonding between H2N and HCCl3 and between NH2 and Cl(HCl2)2. In CCl4 solution the intermolecular hydrogen bonding between the NH2 protons and the Cl atoms of CCl4 is stronger than between the Cl atoms of CHCl3.

Vibrational Frequency Shifts of the Carbonyl Stretching Mode Induced by Solvents: Acetone

1989 ◽  
Vol 43 (6) ◽  
pp. 1053-1055 ◽  
Author(s):  
R. A. Nyquist ◽  
T. M. Kirchner ◽  
H. A. Fouchea
Keyword(s):  
Hydrogen Bonding ◽  
Vibrational Frequency ◽  
Molecular Geometry ◽  
Intermolecular Hydrogen Bonding ◽  
Acceptor Number ◽  
Frequency Shifts ◽  
Solvent Interaction ◽  
Precise Measure ◽  
Solvent Systems ◽  
Solute Solvent Interaction

Variation in the correlations obtained between electron acceptor number (AN) values for each solvent versus the vC=O frequencies for acetone and tetramethylurea in solution with these solvents suggests that the AN values are not a precise measure of solute/solvent interaction for all solute/solvent systems. Factors such as intermolecular hydrogen bonding between solute and solvent and the differences between molecular geometry of the solutes and solvents most likely account for differences in the solute/solvent interaction for different solutes in the same solvents.

Infrared Study of Solute/Solvent Interactions between Separate Chloroform Solutions of Alkanes, Cycloalkanes, Alkenes, Cycloalkenes, Cyclohexadienes, Benzene, and Carbon Tetrachloride

1993 ◽  
Vol 47 (5) ◽  
pp. 560-565 ◽  
Author(s):  
R. A. Nyquist
Keyword(s):  
Bond Distance ◽  
Solvent System ◽  
Electron System ◽  
Intermolecular Bond ◽  
Infrared Study ◽  
Solvent Interaction ◽  
Solvent Interactions ◽  
Solvent Density ◽  
Solute Solvent Interaction ◽  
Cl Atoms

The intermolecular deuteron bonds formed between Cl3CD and ClCCl3, are stronger than between Cl3CD and ClCCl2D, since the Cl atoms of CCl4, are more basic than Cl atoms for CDCl3. The n-alkanes act as a diluent for CDCl3 molecules, and the strength of the intermolecular proton bond in (Cl3CD:ClCCl2D) n complexes increases as n becomes larger. Solvent density also plays an important role in solute/solvent interaction. Increased solvent density causes the CD:Cl or CD:π (of C=C group) intermolecular bond distance to decrease, causing the bond to be stronger. A repulsion exists between the intermolecular π electron system of benzene, 1,3-cyclohexadiene, or 1,4-cyclohexadiene and the chlorine atom δ electrons of CDCl3, and this repulsive effect is a factor in establishing the equilibrium intermolecular bond distance formed between the CD:π bonds of benzene (or cyclohexadienes) and the proton of CDCl3. These conclusions are based on the study of the vCD, vC=C, and v(C=C)2 frequencies vs. mole % CDCl3 (or CHCl3)/solvent system.

Infrared Study of n-Alkanes in CCl4, CDCl3/CCl4, and CDCl3 0.5% Solutions

1993 ◽  
Vol 47 (10) ◽  
pp. 1670-1682 ◽  
Author(s):  
R. A. Nyquist ◽  
S. L. Fiedler
Keyword(s):  
Hydrogen Bonding ◽  
Dipole Moment ◽  
Molecular Hydrogen ◽  
Infrared Study ◽  
Physical Restriction ◽  
Solvent Molecules ◽  
High Degree ◽  
Free Pair ◽  
Cl Atoms ◽  
Positively Charged

Three factors appear to affect n-alkane molecular vibrations in CHCl3/CCl4 solutions. These are: (1) Physical restriction of the vCH3 and vCH2 vibrations by solvent molecules. (2) Inter molecular hydrogen bonding between n-alkane protons and the free pair of electrons on Cl atoms of either CCl4 or CDCl3. The positively charged alkane protons arise during the dipole moment changes, δP/δQ, occurring during a full cycle of the vCH3 and vCH2 modes. (3) The physical restriction of solvent molecules, which is greater in the case of CDCl3 than in the case of CCl4 due to a high degree of CDCl3 orientation about n-alkane molecules due to repulsion of the C-D of CDCl3 by the n-alkane vCH3 and vCH2 protons, which allows stronger C-D:Cl bonds to be formed between solute and solvent.

Infrared Study of Some Organophosphorus Esters in Carbon Tetrachloride and/or Chloroform 1% Solutions

1992 ◽  
Vol 46 (10) ◽  
pp. 1564-1574 ◽  
Author(s):  
R. A. Nyquist ◽  
C. W. Puehl
Keyword(s):  
Carbon Tetrachloride ◽  
Functional Groups ◽  
Solvent System ◽  
Infrared Study ◽  
Solvent Interaction ◽  
Rotational Isomers ◽  
Solvent Systems ◽  
Solute Solvent Interaction ◽  
Organophosphorus Esters

Solvent systems such as CHCl3/CCl4 or CDCl3/CCl4 are useful in showing that organophosphorus esters do exist as rotational isomers in solution. The functional groups such as P=O and POR in organophosphorus esters are the sites of solute/solvent interaction, since their group frequencies are more affected than group frequencies arising primarily within the R group of the organophosphorus esters. This study also shows that different complexes are formed between the solute and solvent systems as well as within the solvent system as the mole % CHCl3/CCl4 or CDCl3/CCl4 increases.

Infrared Study of 4-Substituted Benzaldehydes in Dilute Solution in Various Solvents: The Carbonyl Stretching Mode

1992 ◽  
Vol 46 (2) ◽  
pp. 306-316 ◽  
Author(s):  
Richard A. Nyquist
Keyword(s):  
Hydrogen Bonding ◽  
Functional Groups ◽  
Phenyl Group ◽  
Electronic System ◽  
Fermi Resonance ◽  
Intermolecular Hydrogen Bonding ◽  
Dilute Solution ◽  
Infrared Study ◽  
Solvent Interactions ◽  
Substituted Benzaldehydes

The carbonyl stretching mode in some of the 4- x-benzaldehydes is in Fermi resonance with an overtone of a fundamental which occurs at lower frequency. In general, the unperturbed vC=O frequencies for 4- x-benzaldehydes do appear to correlate with the σp values of the 4- x atom or group. The AN values of the solvents show a pseudo-correlation with the carbonyl and vasym. NO2 stretch vibrations of 4- x-benzaldehyde. However, neither σp nor AN values appear to take into account solute/solvent interactions such as intermolecular hydrogen bonding with the C=O group and with other sites in the molecule such as the phenyl group π system and with the electronic system of other functional groups, since the points in each plot do not correlate in the exact manner in each case.

The Py scale of solvent polarities

1984 ◽  
Vol 62 (11) ◽  
pp. 2560-2565 ◽  
Author(s):  
Dao Cong Dong ◽  
Mitchell A. Winnik
Keyword(s):  
Hydrogen Bonding ◽  
Dimethyl Sulfoxide ◽  
Vapor Phase ◽  
Solvent Polarity ◽  
Solvent Interaction ◽  
Pyrene Fluorescence ◽  
Solute Solvent Interaction

The relative intensities I1/I3 of the vibronic bands of pyrene fluorescence in 94 solvents and the vapor phase are reported. These values, ranging from 0.47 (vapor) to 1.95 (dimethyl sulfoxide) form the Py scale of solvent polarities. This scale is compared to other scales of solvent polarity, particularly the π* scale of Kamlet and Taft in order to assess the contributions of various factors (dipolarity/polarizability, hydrogen bonding, etc.) to the solute–solvent interaction.

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