The absorption bands of the stretching vibrations of the carbonyl groups and the proton-accepting capacity of polyfluorinated ketones and esters

1973 ◽  
Vol 19 (1) ◽  
pp. 926-929 ◽  
Author(s):  
�. M. Marek ◽  
I. P. Kolenko ◽  
A. Ya. Zapevalov ◽  
G. F. Ovchinnikov ◽  
L. A. Perelyaneva
Keyword(s):  
Carbonyl Groups ◽  
Absorption Bands ◽  
Stretching Vibrations

Analysis of the characteristic absorption bands of the stretching vibrations of the lactone carbonyl groups in IR spectra of natural pseudoguaianolides

1990 ◽  
Vol 26 (2) ◽  
pp. 216-217
Author(s):  
�. L. Kristallovich ◽  
I. D. Sham'yanov ◽  
A. Ovezdurdyev ◽  
B. A. Akyev ◽  
M. R. Yagudaev ◽  
...  
Keyword(s):  
Ir Spectra ◽  
Carbonyl Groups ◽  
Absorption Bands ◽  
Characteristic Absorption ◽  
Lactone Carbonyl ◽  
Stretching Vibrations

scholarly journals Effect of Water Leaching on Photodegraded Scots Pine and Spruce Timbers Monitored by FTIR Spectroscopy

Forests ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 833
Author(s):  
Edina Preklet ◽  
László Tolvaj ◽  
Eszter Visi-Rajczi ◽  
Tamás Hofmann
Keyword(s):  
Ftir Spectroscopy ◽  
Scots Pine ◽  
Uv Irradiation ◽  
Chemical Elements ◽  
Uv Light ◽  
Carbonyl Groups ◽  
Water Leaching ◽  
Absorption Bands ◽  
Chemical Changes ◽  
Absorption Increase

The goal of this research was the systematic study and comparison of the divided individual effects of UV light irradiation and water leaching during artificial weathering. Spruce (Picea abies Karst.) and Scots pine (Pinus sylvestris L.) samples were irradiated by ultraviolet (UV) light. Another sequence of samples was treated with the combination of UV irradiation and water leaching. The total extent of UV treatment was 20 days for both series of samples. Time relation of UV irradiation and water leaching was 2:1. The chemical changes were observed by FTIR spectroscopy. The difference spectrum was used for determination of the chemical changes. Degradation of lignin was greater for the leached samples than for the pure UV treated samples. Scots pine suffered greater lignin degradation than spruce, and produced higher absorption increase on the absorption region of unconjugated carbonyls. The unconjugated carbonyl groups were the most responsive chemical elements to leaching. Spruce was more susceptible to leaching of unconjugated carbonyl groups than Scots pine. Two absorption bands of unconjugated carbonyl groups at 1706 and 1764 cm−1 wavenumbers were produced by photodegradation. The absorption band at 1764 cm−1 was more sensitive to water leaching than the band at 1706 cm−1.

Imogolite: a unique aluminosilicate

Clay Minerals ◽  
1969 ◽  
Vol 8 (1) ◽  
pp. 87-99 ◽  
Author(s):  
J. D. Russell ◽  
W. J. McHardy ◽  
A. R. Fraser
Keyword(s):  
Electron Diffraction ◽  
Infrared Absorption ◽  
Chain Structure ◽  
Absorption Bands ◽  
Repeat Units ◽  
Sample Orientation ◽  
Different Types ◽  
Stretching Vibrations ◽  
Diffraction Patterns ◽  
Silicate Chain

The fibrous aluminosilicate imogolite has been studied by electronoptical and infrared absorption methods. Electron diffraction patterns are interpreted in terms of repeat units of 8·4 Å parallel and 23 Å perpendicular to the fibre axis. These spacings can not be reconciled with a continuous silicate chain structure and this conclusion is supported by an Si-O vibration near 930 cm−1. A structure is postulated in which distorted chains of Al-O octahedra are cross-linked through isolated Si2O7 groups.Multiple OH stretching vibrations indicate different types of OH group in the imogolite structure. Absorption bands near 1000, 700 and 600 cm−1 are sensitive to sample orientation. This is attributed to the morphology and dimensions of the imogolite fibres.

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.

Vibrational study and spectra-structure correlations in magnesium disaccharinate heptahydrate, Mg(sac)2⋅7H2O

2008 ◽  
Vol 27 (1) ◽  
pp. 1
Author(s):  
Gligor Jovanovski ◽  
Petre Makreski ◽  
Bojan Šoptrajanov
Keyword(s):  
Experimental Data ◽  
Raman Spectrum ◽  
The Other ◽  
Water Molecules ◽  
Carbonyl Groups ◽  
Structural Units ◽  
Vibrational Study ◽  
Structure Correlations ◽  
Stretching Vibrations ◽  
Ir Bands

Infrared and Raman vibrational spectra of magnesium disaccharinate heptahydrate, Mg(sac)2⋅7H2O, in the 4000–380 cm–1 region (for infrared) and 4000–100 cm–1 region (for Raman) were studied. The assignment of the spectra was based on the experimental data for the previously studied metal saccharinates as well as the literature data for the ab initio calculations on the free deprotonated saccharinato species. Special attention was paid to the analysis of the H2O, CO and SO2 stretching modes. The spectral picture in the regions of the water, carbonyl and sulfonyl stretches is correlated with the number of the crystallographically determined non-equivalent H2O, CO and SO2 structural units. It was found that the presence of seven crystallographically different water molecules in the structure (fourteen different Ow⋅⋅⋅O and Ow⋅⋅⋅N distances) is not reflected in the appearance of the expected fourteen IR bands in the region of the OD stretching vibrations of the isotopically isolated HDO molecules. This must be due to the existence in the structure of several Ow⋅⋅⋅O or Ow⋅⋅⋅N hydrogen bonds with very similar strengths causing an overlap of the corresponding bands in the spectrum. Despite the presence of two carbonyl groups with practically identical C–O distances [124.2(3) and 124.0(3) pm], two clearly separated bands are registered in the carbonyl stretching region of the IR (1660 and 1627 cm–1) and Raman spectrum (1648 and 1620 cm–1). On the other hand, although two nonequivalent SO2 groups are present in the structure of Mg(sac)2⋅7H2O, only one pair of bands due to SO2 stretchings [νas(SO2 and νs(SO2) modes] is registered in the IR spectrum.

Vibrational band intensities in substituted anilines

1957 ◽  
Vol 243 (1233) ◽  
pp. 143-153 ◽  
Keyword(s):  
Linear Relation ◽  
Vibrational Band ◽  
Vibration Band ◽  
Substituted Anilines ◽  
Absorption Bands ◽  
Bond Stretching ◽  
Infra Red ◽  
Analogous Data ◽  
Stretching Vibration ◽  
Stretching Vibrations

The infra-red absorption bands associated with the stretching vibrations of the NH 2 group in a series of meta - and para -substituted anilines have been examined. The effect of the sub­stituet groups upon the frequencies and intensities of the bands has been correlated with their Hammett σ factors. The widths of the bands have also been found to depend upon the position and nature of substituent. The linear relation between log (intensity) and σ suggested previously on the basis of other data has been found to hold in this case too. Measurements in several solvents have been compared, and surprising variations of band intensity have been found. Analogous data have been obtained for the N—H bond stretching vibration band in substituted N -methyl anilines. The effect of ortho substituents has also been examined in a few cases.

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.

Low Temperature Infrared Spectrometric Studies of Difluorodisulfane, Thiothionylfluoride and Difluorotrisulfane

1975 ◽  
Vol 30 (9) ◽  
pp. 1156-1163 ◽  
Author(s):  
Karl-Peter Wanczek ◽  
Claus Bliefert ◽  
Rudolf Budenz
Keyword(s):  
Low Temperature ◽  
Solid Phase ◽  
Frequency Range ◽  
Absorption Bands ◽  
Temperature Spectrum ◽  
Decomposition Products ◽  
Bond Lengths ◽  
Main Decomposition ◽  
Stretching Vibrations ◽  
Sulfur Tetrafluoride

The low temperature IR stretching vibrations of difluorodisulfane (FSSF) and thiothionylfluoride (SSF2), in the solid phase and in a cyclohexane matrix, of the mixtures FSSF -SSF2, FSSF-OSF2 and SSF, -OSF2, and of solid difluorotrisulfane (FS3F) have been investigated. While SSF, forms no distinct oligomers, a dimer with absorption bands at 635 and 682 cm-1 has been detected in the case of FSSF. These differences between FSSF and SSF, are rationalized by the different S-F bond lengths. A structure of the FSSF dimer similar to that of the sulfur tetrafluoride dimer is proposed. The low temperature spectrum of FS3F shows 3 bands in the frequency range between 460 and 1000 cm-1: 590, 605 and 680 cm-1, due to associated molecules. FS3F decomposes on warming. The main decomposition products containing fluorine are FSSF and SSF2. Mechanisms for the rearrangement and decomposition of the three compounds studied are discussed

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