scholarly journals Low-temperature infrared study of ammonium carbamate formation

1984 ◽  
Vol 62 (5) ◽  
pp. 945-948 ◽  
Author(s):  
C. Hisatsune
Keyword(s):  
Solid State ◽  
Low Temperature ◽  
Infrared Spectra ◽  
Low Temperatures ◽  
Hydrogen Ion ◽  
Ion Transfer ◽  
Infrared Study ◽  
Ammonium Carbamate

Two types of infrared spectra observed during the formation of ammonium carbamate [Formula: see text] from the reaction of NH3 and CO2 in the solid state at low temperatures have been re-examined. These spectra had been assigned previously to amorphous and crystalline ammonium carbamate but the present data suggest their origins to be [Formula: see text] and its unstable precursor (NH3)2CO2 in which CO2 is bent. Spectra of amorphous and crystalline ammonium carbamate have been distinguished by comparing the systems NH3/CO2 and NH3/CO2/H2O. Hydrogen ion transfer in the diammoniates occurred at about −80 °C for NH3/CO2 and about −40 °C for ND3/CO2.

A Low Temperature Infrared Study of Self-association in Thiols

1972 ◽  
Vol 50 (22) ◽  
pp. 3594-3600 ◽  
Author(s):  
R. Bicca de Alencastro ◽  
C. Sandorfy
Keyword(s):  
Hydrogen Bonding ◽  
Low Temperature ◽  
Infrared Spectra ◽  
Low Temperatures ◽  
Infrared Study ◽  
Text Type ◽  
Stretching Vibration ◽  
Aliphatic Thiols ◽  
Self Association ◽  
Associated Species

The infrared spectra of several aliphatic thiols and of benzenethiol were measured between 2400 and 2700 cm−1, and 4800 and 5300 cm−1 in a 1:1 mixture of CCl3F and C2F4Br2, at temperatures ranging from 20 to −190 °C. Dimerization takes place at low temperatures and more highly associated species also appear. Free S—H groups are present in the solutions as well as in the pure liquids, even at the lowest temperatures. The association is of the [Formula: see text] type in aliphatic thiols; both [Formula: see text] and [Formula: see text] bonds are found in the case of benzenethiol and α-toluenethiol. Hydrogen bonding has little effect on the anharmonicity of the S—H stretching vibration.

Low-temperature solid-state growth of three-dimensional bicontinuous nanoporous graphene with tunable porosity for lithium–sulfur batteries

2018 ◽  
Vol 6 (24) ◽  
pp. 11405-11415 ◽  
Author(s):  
L. Q. Lu ◽  
N. Schriever ◽  
J. Th. M. De Hosson ◽  
Y. T. Pei
Keyword(s):  
Solid State ◽  
Low Temperature ◽  
Low Temperatures ◽  
Three Dimensional ◽  
Lithium Sulfur Batteries ◽  
Nanoporous Graphene ◽  
State Growth ◽  
Growth Approach ◽  
Lithium Sulfur

In this work we developed a solid-state-growth approach for the synthesis of 3D interconnected bicontinuous nanoporous graphene (NPG) with the aid of nanoporous Ni templates at low temperatures (below 800 °C).

Thermogravimetric study of sequential carbonation and decarbonation processes over Na2ZrO3 at low temperatures (30–80 °C): relative humidity effect

RSC Advances ◽  
2016 ◽  
Vol 6 (71) ◽  
pp. 66579-66588 ◽  
Author(s):  
J. Arturo Mendoza-Nieto ◽  
Heriberto Pfeiffer
Keyword(s):  
Solid State ◽  
Relative Humidity ◽  
Low Temperature ◽  
Low Temperatures ◽  
Humidity Effect ◽  
Temperature Range ◽  
Thermogravimetric Study ◽  
Relative Humidity Effect

Na2ZrO3 was synthetized via solid-state and tested in a low temperature range (30–80 °C) for carbonation and decarbonation processes using RH values between 0 and 80%. Results confirm that it is possible to accomplish successively at least 8 cycles.

AN INFRARED STUDY OF TRIMETHYLAMINE OXIDE, ITS HYDRATE, AND ITS HYDROCHLORIDE

1961 ◽  
Vol 39 (6) ◽  
pp. 1214-1220 ◽  
Author(s):  
Paul A. Giguère ◽  
David Chin
Keyword(s):  
Solid State ◽  
Electron Diffraction ◽  
Hydrogen Bonds ◽  
Infrared Spectra ◽  
Diffraction Data ◽  
Electron Diffraction Data ◽  
Infrared Study ◽  
X Ray ◽  
Trimethylamine Oxide ◽  
Molecular Compounds

The infrared spectra of trimethylamine oxide, its hydrate, and its hydrochloride in the solid state were measured over the range 300 to 3500 cm−1 to ascertain the nature of the bonds in these compounds. From the observed stretching frequencies, 937 cm−1 for N—O and 945 cm−1 for C—N, the corresponding bond lengths are calculated to be 1.44 and 1.50 Å in agreement with X-ray and electron diffraction data. Both these frequencies remain unchanged in the hydrate and the hydrochloride as could be expected for molecular compounds. However, in the hydrochloride most of the evidence points to an ionic constitution. In both the hydrate and the hydrochloride the hydrogen bonds are particularly strong presumably because of the formal charges.

Co(II) complexes with 2-pyrrolidinone

1969 ◽  
Vol 47 (10) ◽  
pp. 1689-1693 ◽  
Author(s):  
O. Bohunovsky ◽  
S. C. Jain ◽  
R. Rivest
Keyword(s):  
Molecular Weight ◽  
Solid State ◽  
Infrared Spectra ◽  
Electronic Spectra ◽  
Cobalt Complexes ◽  
Acetone Solution ◽  
Probable Structure ◽  
Conductivity Measurements ◽  
Infrared Study ◽  
Boron Trichloride

For the known complexes CoL3X2 (X = Cl, Br, and L = 2-pyrrolidinone) a more detailed infrared study was made. Together with the electronic spectra this study indicates dissociation of CoL2X3 into CoL2X2 + L in chloroform and acetone solution. The conductivity measurements and the molecular weight determinations also support dissociation. The probable structure in the solid state is [CoL3X]X. The new 1:1 compound of 2-pyrrolidinone with boron trichloride was prepared to confirm the conclusions made from the infrared spectra of the cobalt complexes.

scholarly journals Rietveld refinement of the low temperature crystal structures of Cs2XSi5O12 (X = Cu, Cd and Zn)

2021 ◽  
Vol 12 (1) ◽  
pp. 60-63
Author(s):  
Anthony Martin Thomas Bell
Keyword(s):  
High Temperature ◽  
Solid State ◽  
Low Temperature ◽  
Rietveld Refinement ◽  
Powder Diffraction ◽  
Low Temperatures ◽  
Powder Diffraction Data ◽  
Space Group ◽  
X Ray ◽  
Silicate Framework

The synthetic leucite silicate framework mineral analogues Cs2XSi5O12 (X = Cu, Cd, Zn) were prepared by high-temperature solid-state synthesis. The results of Rietveld refinement, using 18 keV synchrotron X-ray powder diffraction data collected at low temperatures (8K X = Cu, Zn; 10K X = Cd) show that the title compounds crystallize in the space group Pbca and are isostructural with the ambient temperature structures of these analogues. The structures consist of tetrahedrally coordinated SiO4 and XO4 sharing corners to form a partially substituted silicate framework. Extraframework Cs cations sit in channels in the framework. All atoms occupy the 8c general position for this space group. In these refined structures, silicon and X atoms are ordered onto separate tetrahedrally coordinated sites (T-sites).

Notes: Conformational Changes in Proteins Induced by Low Temperatures: an Infrared Study

1987 ◽  
Vol 42 (11-12) ◽  
pp. 1339-1342 ◽  
Author(s):  
H. L. Casal ◽  
U. Köhler ◽  
H. H. Mantsch ◽  
F. M. Goñi ◽  
J.L.R. Arrondo
Keyword(s):  
Aqueous Solutions ◽  
Conformational Change ◽  
Conformational Changes ◽  
Infrared Spectra ◽  
Low Temperatures ◽  
Helical Structure ◽  
Infrared Study ◽  
Temperature Range

Infrared spectra of hemoglobin (met-hemoglobin) and myoglobin were recorded in the temperature range -110 °C to 30 °C. On cooling hydroalcoholic solutions of hemoglobin, the spectra indicate a conformational change (revealed by the appearance of a band at 1665 cm-1) compatible with the appearance of distortions in its α-helical structure. In the case of myoglobin smaller effects are ob­ served. These conformational changes are entirely reversible and do not occur in frozen aqueous solutions.

An infrared study of the photoisomerization of N-benzylideneaniline

1982 ◽  
Vol 60 (13) ◽  
pp. 1720-1726 ◽  
Author(s):  
J. W. Lewis ◽  
C. Sandorfy
Keyword(s):  
Low Temperature ◽  
Ambient Temperature ◽  
Infrared Spectra ◽  
Polycrystalline Films ◽  
Infrared Study ◽  
Spectral Changes ◽  
Thin Polycrystalline

The infrared spectra of Nujol solutions and thin polycrystalline films of N-benzylideneaniline have been investigated. The 313 nm irradiation of ambient temperature samples produces no observable changes in the infrared spectra, however, similar irradiation of samples maintained at 77 K results in spectral changes that are thermally and photochemically reversible. The infrared spectra of low temperature irradiated samples are interpreted in terms of trans → cis photoisomerization.

The Infrared Spectra of Amino Acids and Some Simple Polypeptides to 33 cm−1 at Room and Liquid Nitrogen Temperatures

1971 ◽  
Vol 25 (2) ◽  
pp. 175-182 ◽  
Author(s):  
William R. Feairheller ◽  
J. T. Miller
Keyword(s):  
Amino Acids ◽  
Low Temperature ◽  
Ir Spectra ◽  
Liquid Nitrogen ◽  
Infrared Spectra ◽  
Low Temperatures ◽  
Low Frequency ◽  
Absorption Bands ◽  
Frequency Bands ◽  
Analytical Information

The ir spectra of a number of amino acids have been studied and the absorption bands in the 400–33 cm−1 region are reported. Spectra were recorded at both room and liquid nitrogen temperatures. It was observed that recording at low temperatures is a useful method for obtaining additional analytical information when the amino acids are in the zwitterion form. Low temperature is also useful in determining the assignment of several of the low frequency bands.

A Low Temperature Infrared Study on the Association of Thiols with Organic Oxygen Bases

1974 ◽  
Vol 52 (5) ◽  
pp. 738-743 ◽  
Author(s):  
R. Bicca De Alencastro
Keyword(s):  
Low Temperature ◽  
Infrared Spectra ◽  
Infrared Study ◽  
Text Type ◽  
Organic Bases

The infrared spectra of mixtures of propane-1-thiol and several oxygen-containing weak organic bases have been measured between 2500 and 2650 cm−1, in a 1:1 mixture of CCl3F and C2F4Br2 at temperatures ranging from 20 to –190 °C. Association of the [Formula: see text] type was observed between propane-1-thiol and 2-methyl-tetrahydrofuran, or cyclopentanone. This association is less important between the thiol and hexachloropropanone. In the case of a thiol–furan mixture association of the [Formula: see text] type is strongly indicated.

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