Hydrogen bonding in chloroform-thioether systems: An N.M.R. spectroscopic study

1974 ◽  
Vol 27 (2) ◽  
pp. 287 ◽  
Author(s):  
KW Jolley ◽  
LM Hughes ◽  
ID Watson
Keyword(s):  
Hydrogen Bonding ◽  
Spectroscopic Study ◽  
Molecular Complexes ◽  
Association Constants ◽  
Enthalpies Of Formation ◽  
Dimethyl Sulphide ◽  
Excess Enthalpies ◽  
Temperature Range ◽  
Enthalpies Of Mixing ◽  
The Ideal

The association constants of molecular complexes of chloroform with dimethyl sulphide, diethyl sulphide, tetrahydrothiophen and thiophen have been obtained by the use of N.M.R. spectroscopy over a temperature range from -50 to +50�C. The enthalpies of formation have been found from these results and used in the ideal associated model to predict the excess enthalpies of mixing.

Studies on Phenylpyruvic Acid, II. Keto-Enol Equilibrium in Water-Dimethylsulphoxide Mixtures

1976 ◽  
Vol 31 (11-12) ◽  
pp. 641-645 ◽  
Author(s):  
L Cassidei ◽  
A Dell 'atti ◽  
O. Sciacovelli
Keyword(s):  
Hydrogen Bonding ◽  
Spectroscopic Study ◽  
Composition Range ◽  
Optimum Composition ◽  
Analytical Determination ◽  
Thermodynamic Quantities ◽  
Phenylpyruvic Acid ◽  
Experimental Conditions ◽  
Temperature Range ◽  
Pure Dmso

Abstract A spectroscopic study of the keto-enol equilibrium of phenylpyruvic acid (PPA) was performed in water-dimethylsulphoxide (DMSO) mixtures, throughout the composition range and in an ex­ tended temperature range. The thermodynamic quantities of the tautomerism were also calculated. The high value of enolization entropy in pure DMSO is attributed to hydrogen bonding of PPA to this solvent. The experimental conditions and the optimum composition range of the H2O-DMSO mixtures for PPA analytical determination were determined.

Hydrogen bonding in chloroform and ether mixtures

1971 ◽  
Vol 24 (10) ◽  
pp. 2047 ◽  
Author(s):  
JR Baker ◽  
ID Watson ◽  
AG Williamson
Keyword(s):  
Hydrogen Bonding ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Mole Fraction ◽  
Proton Magnetic Resonance ◽  
Equilibrium Constants ◽  
Association Constants ◽  
Enthalpies Of Formation ◽  
Temperature Coefficients ◽  
Alkyl Ethers

The hydrogen bonding between chloroform and di-n-alkyl ethers has been studied over the temperature range -50�C to + 50�C using proton magnetic resonance. The measurements of chemical shift have been interpreted in terms of the formation of a 1 : 1 complex between the chloroform and the ether. Mole fraction association constants in the range 1-5 were found. The enthalpies of formation of the complexes deduced from the temperature coefficients of the equilibrium constants varied from -8 kJ mol-1 to -11.7 kJ mol-1.

scholarly journals Hydrogen Bonds: Raman Spectroscopic Study

2021 ◽  
Vol 22 (10) ◽  
pp. 5380
Author(s):  
Boris A. Kolesov
Keyword(s):  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Spectroscopic Study ◽  
Raman Spectra ◽  
Temperature Region ◽  
Vibrational Frequency ◽  
Chemical Compounds ◽  
Raman Spectroscopic ◽  
Raman Spectroscopic Study ◽  
Proton Dynamics

The work outlines general ideas on how the frequency and the intensity of proton vibrations of X–H×××Y hydrogen bonding are formed as the bond evolves from weak to maximally strong bonding. For this purpose, the Raman spectra of different chemical compounds with moderate, strong, and extremely strong hydrogen bonds were obtained in the temperature region of 5 K–300 K. The dependence of the proton vibrational frequency is schematically presented as a function of the rigidity of O-H×××O bonding. The problems of proton dynamics on tautomeric O–H···O bonds are considered. A brief description of the N–H···O and C–H···Y hydrogen bonds is given.

Metabolic response to temperature stress in the Colombian freshwater crab Neostrengeria macropa (H. Milne Edwards, 1853) (Decapoda: Brachyura: Pseudothelphusidae)

2021 ◽  
Author(s):  
David M Hudson
Keyword(s):  
Metabolic Response ◽  
Infrastructure Development ◽  
Predator Prey ◽  
Temperature Range ◽  
Indicator Group ◽  
Response To Temperature ◽  
Performance Results ◽  
The City ◽  
The Ideal

Abstract Freshwater crustaceans are distributed throughout the montane and lowland areas of Colombia, and are therefore a useful indicator group for how aquatic species will respond to climate change. As such, metabolic determination of physiological performance was evaluated for the Colombian pseudothelphusid crab, Neostrengeria macropa (H. Milne Edwards, 1853), over a temperature range inclusive of current temperatures and those predicted by future scenarios in the plateau around the city of Bogotá, namely from 8 °C to 30 °C. The performance results mostly aligned with previous exploratory behavioral determination of the ideal temperature range in the same species, although the metabolism increased at the highest temperature treatments, a point when exploratory behavior declined. These results indicate that this species of montane crab behaviorally compensates for increased thermal stress by decreasing its physical activity, which could have negative predator-prey consequences with changes to community structure as different species undergo climate-mediated geographic range shifts in the region. As this species is endemic to the plateau surrounding Bogotá, it also experiences a number of other stressors to its survival, including infrastructure development and invasive species.

Low-Barrier Hydrogen Bonding in Molecular Complexes Analogous to Histidine and Aspartate in the Catalytic Triad of Serine Proteases

Biochemistry ◽  
1995 ◽  
Vol 34 (21) ◽  
pp. 6919-6924 ◽  
Author(s):  
John B. Tobin ◽  
Sean A. Whitt ◽  
Constance S. Cassidy ◽  
Perry A. Frey
Keyword(s):  
Hydrogen Bonding ◽  
Serine Proteases ◽  
Molecular Complexes ◽  
Catalytic Triad

How many solvent molecules are required to solvate chiral 1,2-diols with hydrogen bonding solvents? A VCD spectroscopic study

2020 ◽  
Vol 22 (3) ◽  
pp. 1525-1533 ◽  
Author(s):  
Luisa Weirich ◽  
Juliana Magalhães de Oliveira ◽  
Christian Merten
Keyword(s):  
Hydrogen Bonding ◽  
Spectroscopic Study ◽  
Spectroscopic Analysis ◽  
Model Systems ◽  
Solvent Interactions ◽  
Solvent Molecules

A VCD spectroscopic analysis of selected model systems for solute–solvent interactions of chiral diols with hydrogen bonding solvents DMSO and ACN.

Reactions of trifluoromethyl radicals. I. Hydrogen abstraction from dimethyl sulphide

1972 ◽  
Vol 25 (4) ◽  
pp. 803 ◽  
Author(s):  
NL Arthur ◽  
KS Yeo
Keyword(s):  
Hydrogen Atom ◽  
Rate Constant ◽  
Hydrogen Abstraction ◽  
Reverse Reaction ◽  
Thermochemical Data ◽  
Hydrogen Atom Abstraction ◽  
Dimethyl Sulphide ◽  
Temperature Range

Hydrogen atom abstraction from (CH3)2S by CF3 radicals has been studied in the temperature range 79-167�: (1) CF3 + CH3SCH3 ←→ CF3H + CH3SCH2 (-1) The rate constant, based on Ayscough's value of 1013.36cmS mol-l s-l for the recombination of CF3 radicals, is given by (k1 in cm3 mol-1 s-l, E in J mol-l): Logk1 = (12.05 � 0.02)-(28710 � 130)/2.303RT Combination of these results with thermochemical data gives a calculated value of log k-1 = 12.2 - 62600/2.303RT for the rate constant of the reverse reaction. ΔH�f(CH3SCH2) and S�(CH3SCH2) are estimated to be 155.6 kJ mol-l and 290 J K-l mol-1 respectively.

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