A.D. Nikolić

NH…π hydrogen bonding: Infrared study of N-cyclohexylformamide-aromatic donor systems

Abstract Hydrogen bonding N -cyclohexylformamide with benzene, toluene, ethylbenzene, n-propylbenzene and n-butylbenzene in CCl 4 solutions has been studied in the fundamental NH stretching vibration region. The formation constants for hydrogen bonded complexes are determined over the temperature range 25–60°C. The corresponding thermodynamic parameters are obtained and it is concluded that a weak hydrogen bond is formed. IR spectral and thermodynamic data are correlated and n-alkyl substituent effects considered. The results are also compared with GLC data obtained for the same systems.

Hydrogen bonding of N-monosubstituted amides. IR study of N-butylacetamides

Abstract The self-association through hydrogen bonding of four isomeric N-butylacetamides has been studied by infrared spectroscopy in carbon tetrachloride, chloroform and benzene. The spectroscopic and thermodynamic parameters for the self-association have been determined. It was found that self-association decreases in the order: N-n-butylacetamide〉N-isobutylacetamide〉N-sec-butylacetamide〉N-tert-butylacetamide. The equilibrium constants and enthalpies of self-association for chloroform and benzene solutions are significantly smaller than in carbon tetrachloride.

Hydrogen bonding of N-monosubstituted amides. IR study of N-ethylacetamide and N-methylpropionamide

Abstract The thermodynamic parameters of N-ethylacetamide (NEA) and N-methylpropionamide (NMP) self-association in carbon tetrachloride, benzene and toluene were determined on the basis of IR spectroscopic data. Also, the present paper reports the spectroscopic and thermodynamic parameters for 1:1 amide - aromatic donor complexes.

Hydrogen bonding of N-monosubstituted amides. IR and NMR study of N-butylbenzamides

Abstract The self-association through hydrogen bonding of N-butylbenzamides has been studied by infrared spectroscopy in carbon tetrachloride, chloroform and benzene. The spectroscopic characteristics and thermodynamic parameters for the self-association have been determined. Also, the carbon tetrachloride and chloroform solutions of the amides have been studied by 1 H NMR spectroscopy. The equilibrium constants for self-association obtained by NMR technique are in good agreement with the corresponding values from infrared measurements.

NH…π hydrogen bonding: FTIR study of N-butylpropionamides-aromatic donor systems

Abstract The present paper reports the results of a FT infrared study in the region of the fundamental NH stretching vibration for N-n-butyl, N-iso-butyl, N-sec-butyl and N-tert-butylpropionamide-aromatic donor systems. The spectroscopic and thermodynamic characteristics for 1:1 amide-aromatic donor complexes are given.

A thermodynamic study of N-n-butylbenzamide solutions using gas-liquid chromatography

Abstract Using g.l.c., the activity coefficients at infinite dilution in the solvent N-n -butylbenzamide have been obtained for 14 solutes of varying saturation and polarity. The infinite dilution partial molar excess enthalpies and entropies of the solute have been calculated from the temperature dependence of the activity coefficients.

Infrared study of N-butylbenzamide - aromatic donor systems

Abstract This paper is a part of an extensive study devoted to the behaviour of N-substituted amides in solutions (ref.1,2). N-n-butylbenzamide (NnBBA), N-iso-butylbenzamide (NiBBA) and N-tert-butylbenzamide (NtBBA) have been studied in CCl 4 - aromatic hydrocarbon (benzene and toluene) solutions by means of IR spectra, using NH fundamental stretching vibration region. Also, NtBBA systems have been examined by UV spectroscopy. On the other hand, NnBBA systems were subjected to gas chromatographic measurements. 1:1 hydrogen bonded complex formation between amide and the aromatic hydrocarbons is considered on the basis of the obtained results.

Configurations in unsymmetrically N-methyl-N-substituted 2-phenylacetamides

Abstract The syntheses of a various N-methyl-N-substituted 2-phenylacetamides of the general formula PhCH 2 CON(CH 3 )R, wherein, R is ethyl, n-propyl, isopropyl and t-butyl group, were performed. The 1 H n.m.r. spectra of these unsymetrically N,N-disubstituted amides have been studied and the peaks have been assigned in each case to the two possible conformational isomers, arising from the lack of free rotation about the C(O)N bond. Although the cis form predominates, the percentage of cis isomer increases as the other nitrogen substituent becomes more bulky. These results are in accordance with our previous investigation of the structures of N-monosubstituted 2-phenylacetamides.

Synthesis and FTIR spectroscopic study of some N-monosubstituted propanamides

Abstract In the present work we investigated the conformations of some N -mono-substituted propanamides of general formula CH 3 CH 2 CONHR, wherein R is chosen from n -(C 1 C 9 )alkyl, cyclo(C 3 C 6 )alkyl, some branched (C 3 C 6 )alkyl or phenyl. The amides were synthesised by the well known Schotten-Baumann reaction—acylation of the corresponding amines with propionyl chloride. On the basis of FTIR data for diluted solutions (concentrations below 10 −3 mol dm −3 ) of N -mono-substituted propanamides in carbon tetrachloride, chloroform, dichloromethane, or a 1:1.5 mixture of benzene and carbon tetrachloride the exact position of the N-H stretching band was established. For spectroscopic data the different conformational isomers were assigned and its structures unequivocally proven. These results are in good accordance with 1 H NMR and MS data.

Synthesis and spectroscopic study of some new rigid N-bicyclo substituted 2-phenylacetamides

Abstract In a continuation of our previous works the conformations of some new rigid N-bicyclo substituted 2-phenylacetamides, PhCH 2 CONHR, were investigated by vibrational, 1 H n.m.r. and mass spectra. N-monosubstituted 2-phenylacetamides were obtained by using the known Schotten-Baumann reaction of acylation of amines with phenylacetyl chloride. From spectroscopic data, the different conformational isomers were assigned and its structure undoubtly proven. On the other hand it can be concluded that the bulkiest substituent on the nitrogen atom have led only to the trans form.