Reactions of the Cumyloxyl and Benzyloxyl Radicals with Strong Hydrogen Bond Acceptors. Large Enhancements in Hydrogen Abstraction Reactivity Determined by Substrate/Radical Hydrogen Bonding

2012 ◽  
Vol 77 (23) ◽  
pp. 10479-10487 ◽  
Author(s):  
Michela Salamone ◽  
Gino A. DiLabio ◽  
Massimo Bietti
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Hydrogen Abstraction ◽  
Strong Hydrogen Bond

Redox-Controlled Hydrogen Bonding: Turning a Superbase into a Strong Hydrogen-Bond Donor

2014 ◽  
Vol 20 (20) ◽  
pp. 5914-5925 ◽  
Author(s):  
Ute Wild ◽  
Christiane Neuhäuser ◽  
Sven Wiesner ◽  
Elisabeth Kaifer ◽  
Hubert Wadepohl ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Strong Hydrogen Bond ◽  
Hydrogen Bond Donor

The solubility of gases and vapours in ethanol - the connection between gaseous solubility and water-solvent partition

1998 ◽  
Vol 76 (6) ◽  
pp. 703-709 ◽  
Author(s):  
Michael H Abraham ◽  
Gary S Whiting ◽  
Wendel J Shuely ◽  
Ruth M Doherty
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Correlation Equation ◽  
Strong Hydrogen Bond ◽  
Log P ◽  
Water Solvent ◽  
Chemical Factors ◽  
Solubility Of Gases ◽  
Solubility Coefficients ◽  
Hydrogen Bond Acidity

Ostwald solubility coefficients, as log L, for solutes in water and ethanol have been combined to give log PEtOH for partition between the two pure solvents. Sixty-four such values have been correlated through our solvation equation, the coefficients of which lead to the conclusion that ethanol and water solvents are equally strong hydrogen-bond bases, but that ethanol is much weaker as a hydrogen-bond acid. A slightly different solvation equation has been used to correlate 68 values of log LEtOH; the coefficients in this equation yield the same conclusions as to the hydrogen-bond acidity and basicity of bulk ethanol. In addition, an analysis of the various terms in the log LEtOH correlation equation allows the elucidation of the various chemical factors that govern the solubility of gaseous solutes in ethanol solvent at 298 K.Key words: solubility, partition, hydrogen-bonding, ethanol, water.

scholarly journals Characterisation of isothiocyanic acid, HNCS, in the solid state: trapped by hydrogen bonding

2016 ◽  
Vol 52 (90) ◽  
pp. 13296-13298 ◽  
Author(s):  
Stefano Nuzzo ◽  
Brendan Twamley ◽  
James A. Platts ◽  
Robert J. Baker
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Solid State ◽  
Dft Calculations ◽  
Strong Hydrogen Bond ◽  
Structural Characterisation ◽  
Image Courtesy

The structural characterisation of [Ph4P][NCS]·HNCS is reported and structurally characterised. DFT calculations and spectroscopy show a strong hydrogen bond (image courtesy of ESO).

Polysulfonylamine, CXLII [1]. Ein supramolekulares Monomer-Dimer-Paar: Starke und schwache Wasserstoffbrücken in den Kristallstrukturen von Pyridinium-dimesylamid und 4,4´-Bipyridindiium-bis(dimesylamid) / Polysulfonylamines, CXLII [1]. A Supramolecular Monomer-Dimer Pair: Strong and Weak Hydrogen Bonding in the Crystal Structures of Pyridinium Dimesylamide and 4,4´-Bipyridinediium Bis(dimesylamide)

2001 ◽  
Vol 56 (10) ◽  
pp. 1041-1051 ◽  
Author(s):  
Oliver Moers ◽  
Ilona Lange ◽  
Karna Wijaya ◽  
Armand Blaschette ◽  
Peter G. Jones
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Low Temperature ◽  
Hydrogen Bonds ◽  
Crystal Structures ◽  
Strong Hydrogen Bond ◽  
Orthorhombic Space Group ◽  
X Ray ◽  
Normalized Parameters ◽  
Hydrogen Bonding Networks

In order to study packing arrangements and hydrogen bonding networks, low-temperature X-ray structures were determined for pyH+(MeSO2)2N- (M, orthorhombic, space group P212121, Z′ = 1) and 4,4′-bipyH22+ ·(MeSO2)2N- (D, monoclinic, C2/c, Z′ = 0.5). The structures consist of ionic formula entities assembled by N+-H···N- hydrogen bonds; the dication in D displays crystallographic C2 symmetry and has its two pyridyl moieties twisted by 43.9°. According to the packing architectures, D represents a supramolecular dimer of the monomeric congener M. In particular, the (MeSO2)2N- ions of the M structure are associated via short C(sp3) - H···O contacts to form a diamondoid network, whereas in D a topologically congruent framework is constructed from weakly hydrogen-bonded [(MeSO2)N-]2 nodes. Hexagonal channels in the anion substructures each include two adjacent stacks of monomeric pyH+ or “dimeric” 4,4-bipyH22+ cations that are linked to the channel walls by the strong hydrogen bond(s) and a set of short Car-H···O contacts. All C - H···O taken into consideration have normalized parameters d(H···O) ≤ 270 pm and θ(C - H···O) ≥ 115°.

Investigation of the Origin of Voltage Generation in Potentized Homeopathic Medicine through Raman Spectroscopy

Homeopathy ◽  
2019 ◽  
Vol 108 (02) ◽  
pp. 121-127 ◽  
Author(s):  
Tara Bhattacharya ◽  
Payaswini Maitra ◽  
Debbethi Bera ◽  
Kaushik Das ◽  
Poonam Bandyopadhyay ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Raman Spectroscopy ◽  
Hydrogen Bonding ◽  
Electrical Properties ◽  
Hydrogen Bonds ◽  
Vibrational Spectra ◽  
Strong Hydrogen Bond ◽  
Oh Groups ◽  
Homeopathic Medicine ◽  
Presence And Absence

Background For the study of homeopathic medicines in proper perspective, emerging techniques in material science are being used. Vibrational spectroscopy is one such tool for providing information on different states of hydrogen bonding as an effect of potentization. The associated change in electrical properties is also correlated with this effect. Objective From the vibrational spectra, the changes in hydrogen bonding due to dilution followed by unidirectional vigorous shaking (together termed potentization) of 91% ethanol and two homeopathic medicines Chininum purum and Acidum benzoicum have been studied. The aim was to correlate the result with the change in the electrical properties of the system. Methods Raman spectroscopy was used to study the vibrational spectra. A U-shaped glass tube (electrochemical cell), where one arm contained bi-distilled water and the other arm alcohol/homeopathic medicine (the arms being separated by a platinum foil), was used to measure the voltage generated across two symmetrically placed platinum electrodes. Results For all samples, it was observed that potentization affected the intensity of OH stretching bands at the frequencies 3240 cm−1, 3420 cm−1 and 3620 cm−1, corresponding to strong hydrogen bond, weak hydrogen bond and broken hydrogen bond, respectively. With the increase in potency, in the presence and absence of the two medicines in ethanol, the number of OH groups linked by strong hydrogen bonds decreased, while the number of OH groups with weak hydrogen bonds increased. With the increase in potentization, the number of OH groups with broken hydrogen bonds showed a difference in the presence and absence of the medicine.The voltage measurements for ethanol show that, with succussion, the magnitude of voltage increased with the two medicines at lower potencies, but not at higher potency where the voltage is lower. Acidum benzoicum, which is acidic in nature, had higher voltage values (113mV, 130 mV and 118 mV at 6C, 30C and 200C, respectively), compared with Chininum purum, which is basic in nature (20 mV, 85 mV and 65 mV at 6C, 30C and 200C, respectively). Conclusion The experimental results indicate a correlation between the vibrational and electrical properties of the homeopathic medicines Acidum benzoicum and Chininum purum at different potencies.

scholarly journals Interplay between hydrogen bonding and n→π* interaction in an analgesic drug salicin

2018 ◽  
Vol 20 (27) ◽  
pp. 18361-18373 ◽  
Author(s):  
Santosh K. Singh ◽  
Prasad Ramesh Joshi ◽  
Robert A. Shaw ◽  
J. Grant Hill ◽  
Aloke Das
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Free State ◽  
Strong Hydrogen Bond ◽  
Conformational Preference ◽  
Analgesic Drug

n→π* interaction is present in the structure of salicin when it is bound to enzyme as well as in free state and the conformational preference of salicin is due to interplay between strong hydrogen bond and n→π* interaction.

One barbiturate and two solvated thiobarbiturates containing the triply hydrogen-bondedADA/DADsynthon, plus one ansolvate and three solvates of their coformer 2,4-diaminopyrimidine

2016 ◽  
Vol 72 (9) ◽  
pp. 705-715 ◽  
Author(s):  
Wilhelm Maximilian Hützler ◽  
Ernst Egert ◽  
Michael Bolte
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Crystal Engineering ◽  
Barbituric Acid ◽  
Thiobarbituric Acid ◽  
Strong Hydrogen Bond ◽  
Hydrogen Bond Acceptor ◽  
Group 2 ◽  
Hydrogen Bonding Site ◽  
Bonding Site

A path to new synthons for application in crystal engineering is the replacement of a strong hydrogen-bond acceptor, like a C=O group, with a weaker acceptor, like a C=S group, in doubly or triply hydrogen-bonded synthons. For instance, if the C=O group at the 2-position of barbituric acid is changed into a C=S group, 2-thiobarbituric acid is obtained. Each of the compounds comprises twoADAhydrogen-bonding sites (D= donor andA= acceptor). We report the results of cocrystallization experiments of barbituric acid and 2-thiobarbituric acid, respectively, with 2,4-diaminopyrimidine, which contains a complementaryDADhydrogen-bonding site and is therefore capable of forming anADA/DADsynthon with barbituric acid and 2-thiobarbituric acid. In addition, pure 2,4-diaminopyrimidine was crystallized in order to study its preferred hydrogen-bonding motifs. The experiments yielded one ansolvate of 2,4-diaminopyrimidine (pyrimidine-2,4-diamine, DAPY), C4H6N4, (I), three solvates of DAPY, namely 2,4-diaminopyrimidine–1,4-dioxane (2/1), 2C4H6N4·C4H8O2, (II), 2,4-diaminopyrimidine–N,N-dimethylacetamide (1/1), C4H6N4·C4H9NO, (III), and 2,4-diaminopyrimidine–1-methylpyrrolidin-2-one (1/1), C4H6N4·C5H9NO, (IV), one salt of barbituric acid,viz. 2,4-diaminopyrimidinium barbiturate (barbiturate is 2,4,6-trioxopyrimidin-5-ide), C4H7N4+·C4H3N2O3−, (V), and two solvated salts of 2-thiobarbituric acid,viz. 2,4-diaminopyrimidinium 2-thiobarbiturate–N,N-dimethylformamide (1/2) (2-thiobarbiturate is 4,6-dioxo-2-sulfanylidenepyrimidin-5-ide), C4H7N4+·C4H3N2O2S−·2C3H7NO, (VI), and 2,4-diaminopyrimidinium 2-thiobarbiturate–N,N-dimethylacetamide (1/2), C4H7N4+·C4H3N2O2S−·2C4H9NO, (VII). TheADA/DADsynthon was succesfully formed in the salt of barbituric acid,i.e.(V), as well as in the salts of 2-thiobarbituric acid,i.e.(VI) and (VII). In the crystal structures of 2,4-diaminopyrimidine,i.e.(I)–(IV),R22(8) N—H...N hydrogen-bond motifs are preferred and, in two structures, additionalR32(8) patterns were observed.

P.M.R. study of intramolecular hydrogen bonding in ortho-amidoanilides and its relation to the spectra of α-acylamidocinnamamide

1973 ◽  
Vol 26 (6) ◽  
pp. 1263 ◽  
Author(s):  
KK Prasad ◽  
RV Venkataratnam
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Magnetic Resonance ◽  
Convenient Method ◽  
Proton Magnetic Resonance ◽  
Intramolecular Hydrogen Bonding ◽  
Strong Hydrogen Bond ◽  
Normal Position ◽  
Tertiary Amide ◽  
Intramolecular Hydrogen

Proton magnetic resonance spectra of some ortho-amido-benzanilides and -acetanilides have been studied. While the secondary amido substituents in the 2-position have been found to form a strong hydrogen bond with the anilide proton, the tertiary amide function is sterically prohibited from doing so with consequent shielding of H 6 from its normal position in the 2-methoxycarbonyl substituted anilides. The abnormal shielding of Hβ in α-acylamidocinnamamides observed earlier has been discussed in relation to the present findings. A convenient method for the preparation of ortho-amidoanilides has been described.

scholarly journals Formation of quinol co-crystals with hydrogen-bond acceptors

2005 ◽  
Vol 61 (1) ◽  
pp. 46-57 ◽  
Author(s):  
Iain D. H. Oswald ◽  
W. D. Samuel Motherwell ◽  
Simon Parsons
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Crystal Structures ◽  
Guest Molecule ◽  
Crystal Packing ◽  
Strong Hydrogen Bond ◽  
Hydrogen Bond Acceptor ◽  
Guest Molecules ◽  
Sterically Hindered

The crystal structures of eight new co-crystals of quinol with pyrazine, piperazine, morpholine, pyridine, piperidine, 4,4′-bipyridine, N-methylmorpholine and N,N′-dimethylpiperazine are reported. Quinol forms 1:1 co-crystals with pyrazine, piperazine and N,N′-dimethylpiperazine, but 1:2 co-crystals with morpholine, 4,4′-bipyridine, N-methylmorpholine, pyridine and piperidine. This difference can be rationalized in most cases by the presence of, respectively, two or one strong hydrogen-bond acceptor(s) in the guest molecule. The exception to this generalization is 4,4′-bipyridine, which forms a 1:2 co-crystal, possibly to optimize crystal packing. All structures are dominated by hydrogen bonding between quinol and the guest molecules. A doubly bridging motif, which connects pairs of quinol and guest molecules via NH...O or CH...O interactions, is present in all but the sterically hindered N,N′-dimethylpiperazine and N-methylmorpholine co-crystals.

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