The infrared spectra of theobromine salts

1967 ◽  
Vol 45 (23) ◽  
pp. 2899-2902 ◽  
Author(s):  
Denys Cook ◽  
Zephyr R. Regnier
Keyword(s):  
Hydrogen Bond ◽  
Nitrogen Atom ◽  
Infrared Spectra ◽  
Imidazole Ring ◽  
Free Base ◽  
Absorption Bands ◽  
Out Of Plane ◽  
Stretching Vibrations ◽  
Deformation Modes ◽  
Infrared Absorption Bands

From the infrared spectra of theobromine salts it is concluded that the salts are probably arranged in hydrogen-bonded centrosymmetric pairs involving [Formula: see text] interactions. [Formula: see text] anion− hydrogen bonds are formed by protonation of the free nitrogen atom (N9) in the imidazole ring. Infrared absorption bands arising from the former hydrogen bond constantly appear near 3 000 cm−1, whereas those from the latter shift from 2 580 to 3 300 cm−1, depending on the anion. In-plane NH and N+H deformation modes give bands near 1 485 and 1 160 cm−1, respectively. Out-of-plane NH modes have been located, but precise assignments are not possible.The assignments for some other bands which show deuteration shifts are detailed, and the carbonyl stretching vibrations which increase in frequency on protonation of the free base are identified.

The infrared spectra of caffeine salts

1967 ◽  
Vol 45 (23) ◽  
pp. 2895-2897 ◽  
Author(s):  
Denys Cook ◽  
Zephyr R. Regnier
Keyword(s):  
Nitrogen Atom ◽  
Infrared Spectra ◽  
Imidazole Ring ◽  
Out Of Plane ◽  
Plane Bending ◽  
Bending Modes

The infrared spectra of caffeine and its salts show that protonation occurs at position 9, the free nitrogen atom in the imidazole ring. N+H stretching and in-plane and out-of-plane bending modes have been assigned with the help of the deuterated salts. Protonation causes changes in some ring modes, accompanied by shifts in the carbonyl stretching frequencies to higher values.

scholarly journals Infrared, 1H and 13C NMR Spectra of N,N-Dichloroarylsulphonamides, 4-X-C6H4SO2NCl2 (X = H, CH3, C2H5, F, Cl or Br) and i-X, j-YC6H3SO2NCl2 (i-X, j-Y = 2,3-(CH3)2, 2,4-(CH3)2, 2,5-(CH3)2, 2-CH3, 4-Cl, 2-CH3, 5-Cl, 3-CH3, 4-Cl, 2,4-Cl2 or 3,4-Cl2)

2003 ◽  
Vol 58 (9-10) ◽  
pp. 563-568
Author(s):  
B. Thimme Gowda ◽  
K. Jyothi ◽  
N. Damodara
Keyword(s):  
Infrared Spectra ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Empirical Correlations ◽  
Absorption Bands ◽  
1H And 13C Nmr ◽  
Modes Of Vibration ◽  
Stretching Vibrations ◽  
Electron Donating Groups ◽  
Infrared Absorption Bands

Several mono- and di-substituted N,N-dichloroarylsulphonamides of the configuration, 4-XC6H4SO2NCl2 (where X = H, CH3, C2H5, F, Cl or Br) and i-X, j-YC6H3SO2NCl2 (where i- X, j-Y = 2,3-(CH3)2, 2,4-(CH3)2, 2,5-(CH3)2, 2-CH3,4-Cl, 2-CH3,5-Cl, 3-CH3,4-Cl, 2,4-Cl2 or 3,4-Cl2), respectively, were prepared, characterised and their infrared spectra in the solid state and NMR spectra in solution state were measured and correlated. Comparison of the infrared spectra of the N,N-dichloroarylsulphonamides with the corresponding arylsulphonamides and Nchloroarylsulphonamides revealed that the infrared absorption bands in the ranges, 790 - 735 cm−1 and 595 - 546 cm−1 are due to N-Cl asymmetric and symmetric stretching vibrations, respectively, and that the effect of ring substitution on the N-Cl frequencies is not consistent. The frequencies in the ranges 1384 - 1333 cm−1 and 1181 - 1143 cm−1 are, respectively, assigned to S=O asymmetric and symmetric modes of vibration. The effect of substitution in the phenyl ring in terms of electron withdrawing and electron donating groups is non-systematic. Since the chemical shift depends on the electron density around the nucleus, empirical correlations relating the chemical shifts to the structures have been considered. The chemical shifts of aromatic protons and carbons in all the N,Ndichloroarylsulphonamides have been calculated by adding substituent contributions to the shift of benzene. Considering the approximation made, the agreement between the calculated and experimental chemical shifts is good.

PROTONATED γ-PYRONES

1963 ◽  
Vol 41 (2) ◽  
pp. 505-514 ◽  
Author(s):  
Denys Cook
Keyword(s):  
Hydrogen Bond ◽  
Solid State ◽  
Hydrogen Atom ◽  
Oxygen Atom ◽  
Plane Deformation ◽  
Carbonyl Oxygen ◽  
Out Of Plane ◽  
Stretching Vibration ◽  
Stretching Vibrations ◽  
Deformation Modes

The vibrational spectra of several salts of 4-pyrone and 2,6-dimethyl-4-pyrone have been measured in the solid state. Deuterium replacement has been used to identify motions of the hydrogen atom which is located on the carbonyl oxygen atom and forms a hydrogen bond with the anion.Bands due to OH stretching vibrations have been observed from 2086 cm−1 in the HCl salt to 3310 cm−1 in the hexachloroantimonate of 2,6-dimethyl-4-pyrone. In-plane hydrogen-deformation modes of the OH group have been found near 1300 cm−1 with a much smaller range in the different salts than the stretching vibration. For the 4-pyrone salts the OH stretching vibrations were at similar frequencies, and the in-plane hydrogen-deformation frequencies were close to 1340 cm−1. Bands due to the out-of-plane deformation were not observed.Aqueous solutions of 2,6-dimethyl-4-pyrone hydrochloride at various concentrations showed the presence of both protonated and neutral molecules.

Infrared Spectra of 2,9-Dimethyl-1,10-phenanthroline, Its Hydrates and Acid Perchlorate

1962 ◽  
Vol 15 (3) ◽  
pp. 425 ◽  
Author(s):  
ECM Grigg ◽  
JR Hall ◽  
RA Plowman
Keyword(s):  
Infrared Spectra ◽  
Plane Motion ◽  
Ring System ◽  
Hydrogen Atoms ◽  
Absorption Bands ◽  
Out Of Plane ◽  
Intense Absorption ◽  
Infrared Absorption Spectra ◽  
Stretching Vibrations ◽  
Phase Out

Infrared absorption spectra of 2,9-dimethyl-1,10-phenanthroline (dmp), dmp 0.5H2O, dmp 2H2O, and dmp HClO4 have been obtained over the range 4000-650 cm-1. Bands between 1610 and 1545 cm-1 are attributed to stretching vibrations within the phenanthroline ring system. The in-phase out-of-plane motion of the ring hydrogen atoms is associated with intense absorption at 845 cm-1. A strong band is observed at 728 cm-1 which cannot be accounted for in terms of an out-of-plane CH deformation. The perchlorate is characterized by shifts of the strongest absorption bands observed in the spectra of dmp and the hydrates.

Pyrrole Studies. I. The Infrared Spectra of 2-Monosubstituted Pyrroles

1963 ◽  
Vol 16 (1) ◽  
pp. 93 ◽  
Author(s):  
RA Jones
Keyword(s):  
Infrared Spectra ◽  
Infrared Absorption ◽  
Absorption Bands ◽  
Infrared Absorption Bands

The positions and intensities of the characteristic infrared absorption bands of the nucleus are recorded and discussed for thirty-five 2-monosubstituted pyrroles.

Synthesis, spectral and electrochemical study of coordination molecules Cu4OX6L4: 4-cyanopyridine Cu4OBrnCl(6−n)(4-CNpy)4 complexes

2010 ◽  
Vol 64 (3) ◽  
Author(s):  
Gregor Ondrejovič ◽  
Adela Kotočová ◽  
Marian Koman ◽  
Peter Segľa
Keyword(s):  
Cyclic Voltammetry ◽  
Infrared Spectra ◽  
Electronic Spectra ◽  
Pyridine Ring ◽  
Pyridine Complexes ◽  
Half Wave ◽  
Out Of Plane ◽  
Donor Acceptor ◽  
Back Bonding ◽  
Stretching Vibrations

AbstractNew 4-cyanopyridine halide and mixed-halide Cu4OBrnCl(6−n)(4-CNpy)4 complexes (4-CNpy = 4-cyanopyridine, n = 0–6) were synthesised, characterised, and studied by infrared spectra, electronic spectra, and cyclic voltammetry. Infrared spectra revealed donor-acceptor vibrational couplings of the Cu4O, Cu-Cl, and Cu-N stretching vibrations with the in-plane and out-of-plane pyridine ring vibrations. The infrared spectra, electronic spectra, and half-wave potentials correspond to a weak donor and a strong acceptor behaviour of the 4-cyanopyridine ligands and to π-back bonding, Cu(II)→pyridine rings. The results were compared with the related pyridine and 4-substituted pyridine complexes.

The intramolecular hydrogen bond in some β-nitroalcohols. Chemistry of nitroalkanes. Part CXIX

1977 ◽  
Vol 55 (13) ◽  
pp. 2504-2509 ◽  
Author(s):  
E. Lipczyńska-Kochany ◽  
T. Urbański
Keyword(s):  
Hydrogen Bond ◽  
Experimental Evidence ◽  
Intramolecular Hydrogen Bond ◽  
Infrared Absorption ◽  
Nmr Spectra ◽  
Absorption Bands ◽  
Intramolecular Hydrogen ◽  
Infrared Absorption Bands

New experimental evidence is given on the existence of an intramolecular hydrogen bond in β-nitroalcohols between the nitro and hydroxylic groups. The conclusion is based on examination of na → π* and infrared absorption bands and nmr spectra.

The infra-red absorption bands associated with the COOH and COOD groups in dimeric carboxylic acids. I. The region from 1500 to 500 cm -1

1953 ◽  
Vol 216 (1125) ◽  
pp. 247-266 ◽  
Keyword(s):  
Carboxylic Acids ◽  
Raman Spectra ◽  
Crystalline Solid ◽  
Cooh Group ◽  
Absorption Bands ◽  
Solid States ◽  
Infra Red ◽  
Out Of Plane ◽  
Stretching Vibrations ◽  
Skeletal Deformation

The infra-red spectra of a considerable number of carboxylic acids and their COOD derivatives have been investigated between 1500 and 500 cm -1, as dimeric units in the liquid or crystalline solid states. Under these conditions the COOH group is shown usually to give rise to strong absorption bands in the regions 1420 ±20, 1300 ± 15 and 935 ± 15 cm -1 . The first two of these are found to correspond to closely coupled OH deformation and C—O stretching vibrations occurring in the plane of the (COOH) 2 dimeric ring; the latter is caused by the out-of-plane OH deformation vibration. COOD groups have absorption bands in the ranges 1350 ±50, 1050 ± 10 and 675 ±25 cm -1 , which can be assigned respectively to the C—O stretching mode and the in-plane and out-of-plane OD deformation vibrations. Less constant absorption bands of the COOH group between 700 and 575 cm -1 are attributed to O—C = O skeletal deformation vibrations, and the corresponding bands are found at slightly lower frequencies in the spectra of the COOD derivatives. The results of the infra-red investigation are compared with the Raman spectra of such acids and with related infra-red and Raman frequencies of other molecules. Infra-red spectra of some equimolecuiar mixtures of acids with water have also been studied.

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