Salim Y. Hanna

Solvent effects on OH stretching frequencies for 1-arylallyl alcohols.

A series of 1-arylallyl alcohols were prepared and its OH stretching frequencies measured in 20 different non-HBD solvents at room temperature. It is noticed that the observed stretching bands were highly sensitive to the nature of the solvents. Multiple parameter equations were applied to investigate the solvent effects on the O-H stretching frequency. The most significant solvent parameters were the nucleophilicity measuring parameter (B) and Gutmann donor number (DN), whilst the electrophilicity measuring parameter (E) is not significant.

Substitutent effects on the geometrical properties of 1-phenylallyl alcohol

Abstract Optimized geometrical parameters, electron densities, heats of formation and stabilization energies have been obtained on X-substituted phenylallyl alcohols, where X is H, OCH3, NH2, CN, F and CH3 at ortho, meta, and para positions, using MINDO-Forces SCF-molecular orbital calculations. The substituent effects on the geometrical parameters and the electron density are discussed.

MINDO – Forces Calculation of Some Substituted Phenylallyl Cations

MINDO-Forces SCF-molecular orbital calculations with complete geometry optimization have been performed on x-substituted phenylallyl cations, where x is H, OCH3, NH2, NO2, CN, F and CH3, in ortho, meta, or para positions. Optimized geometrical parameters, electron densities, heats of formation and stabilization energies were obtained. The substitutent effect on the geometrical parameters and the electron density are discussed by correlation analysis.

Solvent effects on OH stretching frequencies for 3-arylallyl alcohols

Eight 3-arylallyl alcohols were prepared, and their OH stretching frequencies were measured in twenty non-HBD solvents at room temperature. The observed stretching bands were highly sensitive to the nature of the solvents. Multiple parameter equations were applied to investigate the solvent effect on the O-H stretching frequency. The most significant solvent parameters were the nucleophilicity parameter and the Gutmann donor number, while the electrophilicity parameter was not significant

The N-substitution and N-oxidation effects on the carbon-13 chemical shift of some substituted anilines

Abstract The N -substitution and the N -oxidation effects on the carbon-13 chemical shift for all ring carbons of some substituted anilines are discussed. Correlation of the N -substitution effect with substituent constants by means of a linear combination of two empirical parameters, σ I and σ R has been studied. The best correlation was obtained between the N -methylation effect and the substituent constants.

Spectroscopic Studies of Some Organic Compounds: Solvent Effects on 1H NMR Shift of Amine Proton of Morpholine

Abstract The influence of the aprotic Solvents on the 1H NMR spectra of the N-H proton has been studied. The chemical shift shows quite good correlation with the solvatochromic parameters, π∗, β, and α, while a fair correlation with the Gutmann donor and acceptor numbers were obtained.

Spectroscopic Studies of Some Organic Compounds: Aprotic Solvent Effects on Electronic Absorption Spectra of Nicotinamide

Abstract The electronic absorption spectra of nicotinamide were measured in seventeen aprotic solvents. The solvatochromic method is used to unravel solvent polarity and hydrogen bonding effects on π − π∗ transition. Solvent effects are rationalized in terms of the solvatochromic parameters: π∗, δ, α, and β.

Studies of Tertiary Amine Oxides. Part1 15. Carbon - 13 nuclear magnetic resonance spectra of some N-(4-substituted phenyl) piperidine, the corresponding N-oxides, and their thermal-rearrangement product

Abstract The carbon-13 chemical shifts of seven N-(4-substituted phenyl) piperidine; the corresponding N-oxides, and their thermal rearrangement products were analyzed and assigned. The N-oxidation effect on the carbon-13 chemical shift is discussed, a correlation of N-oxidation effect with substituent constant (σp, σm, σI and σR) has been studied; dual substituent-parameter equation produce better correlation.

Studies of tertiary amine oxides. Part 14. Protic solvent effects on the rate of thermal rearrangement of N-(2,4-dinitrophenyl)piperidine N-oxide

The rate of rearrangement of N-(2,4-dinitrophenyl)piperidine N-oxide has been studied in 15 hydroxylic solvents. The first-order rate coefficients (kobs) have been successfully correlated with different solvent parameters. The results are explained in terms of the nucleophilic solvation capability of the solvent which in turn supports the previously proposed three-membered ringactivated complex. Moreover, the role of the HBD ability of the solvent in this reaction is also pronounced, particularly since reaction in alcohols exhibits lower reactivity and higher enthalpy and entropy of activation compared with aprotic solvents.

Studies of tertiary amine oxides. Part 8. Rearrangement of N-(2,4-dinitrophenyl)-piperidines and -morpholine N-oxides in aprotic solvents

The N-oxides of N-(2,4-dinitrophenyl)-piperidines and -morpholine undergo thermal rearrangement to the substituted hydroxylamines. The kinetics of the rearrangement were studied in aprotic solvents at four or five temperatures. Steric and polar factors have great influence on the rate of rearrangement. The kinetic results together with cross-over experiments are in full agreement with an intramolecular cyclic mechanism (SNi).