SPECTROSCOPIC STUDIES OF ALCOHOLS: III. FUNDAMENTAL OH STRETCHING BANDS OF 2,2-DI- AND 2,2,2-TRI-HALOETHANOLS

1964 ◽  
Vol 42 (2) ◽  
pp. 340-346 ◽  
Author(s):  
P. J. Krueger ◽  
H. D. Mettee
Keyword(s):  
Spectroscopic Studies ◽  
Kcal Mole ◽  
Temperature Dependent ◽  
Hydrogen Bond Interaction ◽  
Constrained System ◽  
Trans Conformer ◽  
Bond Polarizability ◽  
Inductive Effects ◽  
Geometrically Constrained ◽  
Bond Polarization

The OH stretching region was examined for the compounds F3CCH2OH, Cl2CHCH2OH, Cl3CCH2OH, and Br3CCH2OH in dilute CCl4 solution. The first two compounds exhibit temperature-dependent band asymmetry which is due to trans–gauche equilibria arising from rotation about the C—O bond, with relatively small populations in the trans forms. Enthalpy differences of 3.3 and 2.4 kcal/mole between the conformers were obtained for these two compounds respectively. Although symmetrical at lower temperatures, the band for Cl3CCH2OH shows the presence of a small amount of the trans conformer at temperatures above 45 °C. These results are discussed in terms of intramolecular OH … X hydrogen bond interaction, inductive effects, non-bonded interactions, O—H bond polarization, C—X bond polarizability, and the size of the halogen atoms in a geometrically constrained system.

SPECTROSCOPIC STUDIES OF ALCOHOLS: V. INTRAMOLECULAR HYDROGEN BONDS IN 2-CYANOETHANOL AND IN SOME NITROALCOHOLS

1965 ◽  
Vol 43 (10) ◽  
pp. 2888-2895 ◽  
Author(s):  
P. J. Krueger ◽  
H. D. Mettee
Keyword(s):  
Hydrogen Bonds ◽  
Spectroscopic Studies ◽  
Enthalpy Change ◽  
Kcal Mole ◽  
Gauche Conformation ◽  
Trans Form ◽  
Trans Conformer ◽  
Enthalpy Difference ◽  
Intramolecular Hydrogen ◽  
Hydrogen Bonded

The enthalpy difference between the trans and the intramolecularly hydrogen bonded gauche conformation of 2-cyanoethanol in dilute CCl4 solution is shown to be −0.14 ± 0.03 kcal/mole from the temperature dependence of the fundamental OH stretching bands. At higher concentrations cyclic dimers with double OH … O bonds form. The enthalpy change on dimerization is −6.1 ± 0.3 kcal/mole. A small percentage of dimers with acylic OH … O bonds are also present, but these are thermodynamically less stable than the cyclic dimers.Intramolecular hydrogen bonds are found between OH and NO2 groups in some 2-nitro-alcohols, leading to stabilization of the gauche form with respect to the trans form. For 2-nitroethanol the trans conformer is in equilibrium with two intramolecularly hydrogen bonded conformers (ΔH = −0.40 ± 0.10 and −0.71 ± 0.09 kcal/mole respectively). 2,2-Dinitro-propanol and 2-methyl-2-nitro-1,3-propanediol show complex νOH bands due to trans and intramolecularly hydrogen bonded gauche conformers. 2,2,2-Trinitroethanol has a relatively narrow symmetrical OH peak at temperatures up to 55 °C which is assigned to the exclusively populated intramolecularly hydrogen bonded conformation.

Energy method for modelling delamination buckling in geometrically constrained systems

2003 ◽  
Vol 217 (9) ◽  
pp. 1015-1026 ◽  
Author(s):  
B J Hicks ◽  
G Mullineux ◽  
C Berry ◽  
C J McPherson ◽  
A J Medland
Keyword(s):  
Finite Element ◽  
Full Range ◽  
Constrained Systems ◽  
Third Party ◽  
Constrained System ◽  
Finite Element Approach ◽  
Delamination Buckling ◽  
Element Approach ◽  
Geometrically Constrained ◽  
Energy Formulation

Delamination buckling analysis of laminates is of considerable interest to the mechanical and materials engineering sectors, as well as having wider applications in geology and civil engineering. With advances in computing power, the ability to model ever increasingly complex problems at more detailed levels becomes more of a reality. However, many of the common finite element packages, with the exception of all but the most specialized, do not perform particularly well where complex non-linear problems are dealt with. In many cases, these packages can fail to determine the full range of solutions or accurately predict the properties and geometry of the final state. This is particularly the case where large deformations and buckling of laminates are considered. Because of this, many researchers prefer to use what they perceive to be more reliable techniques, such as the symbolic computation of the underlying differential equations, rather than finite element approaches. The use of finite element packages is further frustrated by the steep learning curve and implicit restrictions imposed by using third-party software. In this paper, a finite element approach and an energy formulation method are considered and used to model the delamination buckling in a geometrically constrained system. These methods are compared with experimental results and their relative merits are discussed. In particular, the accuracy and the ability to represent the geometry of the buckled system are discussed. Both the finite element approach and the energy formulation are described in detail and the numerical results are compared.

Investigations of the molecular basis for the temperature-dependent insolubility of cryoglobulins. II. Spectroscopic studies of the IgM monoclonal cryoglobulin McE

Biochemistry ◽  
1977 ◽  
Vol 16 (13) ◽  
pp. 2986-2994 ◽  
Author(s):  
C. R. Middaugh ◽  
G. J. Thomas ◽  
B. Prescott ◽  
M. E. Aberlin ◽  
G. W. Litman
Keyword(s):  
Molecular Basis ◽  
Spectroscopic Studies ◽  
Temperature Dependent

Heat stability of milk: interrelationship between assay temperature, pH and agitation

1981 ◽  
Vol 48 (1) ◽  
pp. 123-129 ◽  
Author(s):  
Douglas B. Hyslop ◽  
Patrick F. Fox
Keyword(s):  
Heat Stability ◽  
Kcal Mole ◽  
Temperature Dependent ◽  
Total Solids ◽  
Ph Values ◽  
Assay Procedure ◽  
Concentrated Milk ◽  
The Stability ◽  
Ph Curve ◽  
Maximum Minimum

SummaryAs determined by the standard subjective assay procedure, the minimum in the heat stability–pH curve of milk persisted down to at least 116 °C. However when samples were not agitated during heating the minimum became progressively less pronounced as the assay temperature was lowered and it disappeared at approximately 116 °C. Activation energies (Ea) for unagitated samples were approximately 30 Kcal/mole at pH 6·87 (maximum) and at pH 7·18, throughout the temperature range 116–145 °C and for the pH 6·95 (minimum) sample at 116–125 °C; however Eα for the pH 6.95 sample increased to approximately 100 Kcal/mole in the range 127–135 °C suggesting that some highly temperature-dependent reaction had occurred and caused premature coagulation at certain pH values, i.e. to a heat stability minimum. The stability of concentrated milk (20% total solids) was very low at pH values above 6·9, regardless of whether the samples were agitated or not during heating and the maximum/minimum in the heat stability–pH curve persisted down to at least 90 °C in both agitated and quiescent samples.

STRUCTURAL, DIELECTRIC AND TEMPERATURE DEPENDENT RAMAN SPECTROSCOPIC STUDIES ON SWIFT HEAVY ION IRRADIATED TGS CRYSTALS

2011 ◽  
Author(s):  
P. K. Bajpai ◽  
Deepak Shah ◽  
Ravi Kumar ◽  
Ashok Kumar ◽  
R. S. Katiyar ◽  
...  
Keyword(s):  
Heavy Ion ◽  
Spectroscopic Studies ◽  
Temperature Dependent ◽  
Raman Spectroscopic ◽  
Swift Heavy Ion

scholarly journals X-ray Absorption Spectroscopic studies of Single Crystal SrFeO3-δ

2014 ◽  
Vol 70 (a1) ◽  
pp. C1527-C1527
Author(s):  
Shang Hsien Hsieh ◽  
Mukta Vinayak Limaye ◽  
Shashi Bhushan Singh ◽  
Yu Cheng Shao ◽  
Yu Fu Wang ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Single Crystal ◽  
Thermal Hysteresis ◽  
Spectroscopic Studies ◽  
Temperature Dependent ◽  
Zone Method ◽  
Edge Structure ◽  
X Ray ◽  
Length Changes ◽  
X Ray Absorption

We have prepared a high quality single crystal of SrFeO3-δ (δ ~ 0.14) by the floating-zone method to study the electronic and atomic structures using temperature-dependent x-ray absorption near-edge structure (XANES), x-ray linear dichroism (XLD), and extended x-ray absorption fine structure (EXAFS) at the O K-edge, Fe L3,2- and K-edge. Resistivity measurements indicate that the SrFeO2.86 shows an anisotropic behavior, and thermal hysteresis behavior between 70 K and 40 K. The temperature dependent Fe K-edge EXAFS studies shows that the Fe-O bond length changes in ab-plane below transition temperature. The XLD results illustrate that as temperature is reduced from room temperature to below the transition temperature, the preferential occupancy of Fe majority-spin eg orbitals changes from the 3d3z2-r2 to 3dx2-y2, but restore to 3dx2-y2 after thermal hysteresis. Experimental findings suggest that the charge transfer during thermal hysteresis is induced by lattice distortions of the FeO6 octahedra in SrFeO2.86.

SPECTROSCOPIC STUDIES OF ALCOHOLS: II. THE CONFORMATION OF 2-HALOETHANOLS IN CARBON TETRACHLORIDE SOLUTION

1964 ◽  
Vol 42 (2) ◽  
pp. 326-339 ◽  
Author(s):  
P. J. Krueger ◽  
H. D. Mettee
Keyword(s):  
Carbon Tetrachloride ◽  
Equilibrium Constants ◽  
Spectroscopic Studies ◽  
Kcal Mole ◽  
Band Shift ◽  
Carbon Tetrachloride Solution ◽  
Hydrogen Bond Interactions ◽  
Conformational Equilibria ◽  
Intramolecular Hydrogen ◽  
Conformational Free Energy

Of the five conformers predicted for 2-haloethanols, only two (halogen and OH trans and gauche) can be positively identified by high resolution infrared spectroscopy. From the temperature dependence of the relative intensities of the fundamental OH stretching bands of the trans and gauche forms of the compounds XCH2CH2OH2 where X = F, Cl, Br, and I, the gauche conformers are shown to be energetically favored in dilute carbon tetrachloride solution, with enthalpy differences between the two conformers of 2.07 ± 0.53, 1.20 ± 0.09, 1.25 ± 0.08, and 0.81 ± 0.09 kcal/mole respectively. Equilibrium constants and the conformational free energy and entropy differences are reported. Inter- and intra-molecular OH … X hydrogen-bond interactions are found to be similar in that the enthalpy increases in the order X = I < Br < Cl < F, and is linearly related to a decrease in the fundamental OH band shift, in contrast to the Badger–Bauer relationship. The molecular and thermodynamic factors governing conformational equilibria involving intramolecular hydrogen bonds are discussed.

scholarly journals Spectroscopic studies on the temperature-dependent molecular arrangements in hybrid chitosan/1,3-β-D-glucan polymeric matrices

2020 ◽  
Vol 159 ◽  
pp. 911-921 ◽  
Author(s):  
Barbara Gieroba ◽  
Anna Sroka-Bartnicka ◽  
Paulina Kazimierczak ◽  
Grzegorz Kalisz ◽  
Agnieszka Lewalska-Graczyk ◽  
...  
Keyword(s):  
Spectroscopic Studies ◽  
Temperature Dependent ◽  
Polymeric Matrices
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