'Breaking' and formation of hydrogen bonds by proton donor anesthetics

1977 ◽  
Vol 55 (18) ◽  
pp. 3211-3217 ◽  
Author(s):  
Rachel Massuda ◽  
C. Sandorfy
Keyword(s):  
Hydrogen Atom ◽  
Hydrogen Bonds ◽  
Electron Acceptor ◽  
Proton Donor ◽  
Point Of View ◽  
Mobile Hydrogen ◽  
Competitive Mechanism ◽  
Text Types ◽  
Anesthetic Potency ◽  
Mobile Hydrogen Atom

It has been shown previously that halofluorocarbons having anesthetic potency hinder the formation of hydrogen bonds (HB) of the [Formula: see text] types and it has been suggested that this is linked to a competitive mechanism involving another type of association. Since some of the most potent and widely used fluorocarbon anesthetics contain a mobile hydrogen atom the question arises if in such molecules the competitive mechanism involves the formation of HB's with the anesthetic as the proton donor instead of, or in addition to, association due to the electron acceptor properties of the higher halogens as seems to be the case for those fluorocarbon anesthetics which contain no hydrogen. Chloroform, halothane, methoxyflurane, enflurane, and 4,5-dichloro-2,2-difluoro-l,3-dioxolane have been studied from this point of view with the result that both mechanisms appear to operate.

Anesthesia and hydrogen bonding. A semi-quantitative infrared study at room temperature

1978 ◽  
Vol 56 (12) ◽  
pp. 1681-1686 ◽  
Author(s):  
Ginette Trudeau ◽  
K. C. Cole ◽  
Rachel Massuda ◽  
C. Sandorfy
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Room Temperature ◽  
Quantitative Relationship ◽  
Bond Breaking ◽  
Infrared Study ◽  
Text Types ◽  
Theories Of Anesthesia ◽  
Anesthetic Potency

It has been shown previously that certain anesthetics hinder the formation of hydrogen bonds of the [Formula: see text] types. An attempt bas now been made to correlate this hydrogen bond 'breaking' property with anesthetic potency. As a measure of the former, relative intensifies of infrared bands related to 'free' and hydrogen bonded species were used. The band which was chosen for this purpose is the OH or NH stretching + in-plane bending combination band. This made it possible to carry out the measurements at room temperature. A semi-quantitative relationship has been found. Its significance for the theories of anesthesia is discussed.

scholarly journals The mechanism of chemical change. Part II.—Catalysis of the mutarotation of beryllium benzoylcamphor

1931 ◽  
Vol 132 (820) ◽  
pp. 398-415 ◽  
Keyword(s):  
Hydrogen Atom ◽  
Chemical Change ◽  
Preceding Paper ◽  
Internal Electrolysis ◽  
Mobile Hydrogen ◽  
Acid And Base ◽  
Alternative Position ◽  
The One ◽  
Single Bonds ◽  
Mobile Hydrogen Atom

The preceding paper of this series on “Promotion and Arrest of Mutarotation of Tetra-acetylglucose in Ethyl Acetate” described the most successful experiments that have yet been made with a view to controlling the facile isomeric changes which depend on the migration of a hydrogen atom with a concurrent re-arrangement of bonds in the molecule of an unsaturated (or cyclic) organic compound. These “desmotropic” or “prototropic" changes proceed normally only in presence of an amphoteric solvent, such as water or a mixture of pyridine and cresol, which is able simultaneously to remove a proton from one position in the molecule, and to supply a proton in the alternative position. The re-arrangement of single and double bonds, which accompanies the migration of the hydrogen atom, provides a conducting mechanism whereby an electron can be transferred through the intermediate conjugated system from one point of attachment of the mobile hydrogen atom to the other. This electronic migration makes it possible to neutralise the negative charge produced by the removal of a proton from the one point of attachment, together with the positive charge produced by the addition of a proton to the second point of attachment, so that the mobile hydrogen atom need not carry its electron with it, but can migrate in the form of an ion. The mechanism of the prototropic change can then be represented as a sort of internal electrolysis in which the acid and base act as negative and positive poles, whilst the conjugated double and single bonds of the organic molecule take the place of the electrolyte. Thus, if we represent the acid and base as HA and B, and the two forms of the prototropic compound as HS and SH, the reversible isomeric change can be represented by the following scheme: B + HS + HA ⇌ + BH + SH + A̅. In this scheme the arrows show the direction in which the electron migrates through the molecule as a result of the bond-shifting, whilst the proton migrates in the same direction through the medium . Apart from the prototropic change, the action formulated above is a simple reversible neutralisation of an acid and base, which, if the prototropic compounds were eliminated, could be represented by the equation B + HA ⇌ + BH + A̅, e. g. , NH 3 + HAc ⇌ + NH + A̅c.

Modelling of Staebler-Wronski Effect in Hydrogenated Amorphous Silicon under Moderate and Intense Illumination

2004 ◽  
Vol 230-232 ◽  
pp. 221-232 ◽  
Author(s):  
A.F. Meftah ◽  
A.M. Meftah ◽  
A. Merazga
Keyword(s):  
Hydrogen Atom ◽  
Amorphous Silicon ◽  
Radiative Recombination ◽  
Hydrogenated Amorphous Silicon ◽  
Defect Site ◽  
Mobile Hydrogen ◽  
Proposed Model ◽  
Staebler Wronski Effect ◽  
Hydrogenated Amorphous ◽  
Mobile Hydrogen Atom

A new model is developed for the Staebler-Wronski effect (SWE) in intrinsic a-Si:H. In this model, non-radiative recombination of the photogenerated carriers occurs at a weak bond close to a SiHHSi configuration, which allows a local creation of defect of the SiHD type. This defect can be annihilated by mobile hydrogen atom that has been emitted from an other distant SiHD defect as a result of non-radiative recombination at this defect site. In this study we have considered illumination intensities in the moderate and intense illumination range. In both cases, the proposed model reproduces many experimental features of the SWE known in the literature.

Demotic Palaeography

2020 ◽  
pp. 604-617
Author(s):  
Joachim Quack ◽  
Jannik Korte ◽  
Fabian Wespi ◽  
Claudia Maderna-Sieben
Keyword(s):  
Point Of View ◽  
Research History ◽  
Text Types

This chapter covers all aspects of Demotic palaeography. It deals with its research history and names its most important tools. Palaeographic methodology and issues of sign definition are discussed from a Demotic point of view. The problems of classifying Demotic scribal hands and assigning them to chronologically and topographically defined palaeographic stages are addressed. The chapter furthermore discusses the influence of text types, palaeographic “registers,” and scribal schools on sign shapes as well as the interactions between Demotic and other Egyptian scripts. It addresses the categorization of the Demotic signs and also orthography.

scholarly journals Organotin(IV) selenate derivatives – Crystal structure of [{(Ph3Sn)2SeO4} ⋅ CH3OH] n

2021 ◽  
Vol 44 (1) ◽  
pp. 213-217
Author(s):  
Waly Diallo ◽  
Hélène Cattey ◽  
Laurent Plasseraud
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Hydrogen Bonds ◽  
Point Of View ◽  
Intermolecular Hydrogen Bonds

Abstract Crystallization of [(Ph3Sn)2SeO4] ⋅ 1.5H2O in methanol leads to the formation of [{(Ph3Sn)2SeO4} ⋅ CH3OH] n (1) which constitutes a new specimen of organotin(IV) selenate derivatives. In the solid state, complex 1 is arranged in polymeric zig-zag chains, composed of alternating Ph3Sn and SeO4 groups. In addition, pendant Ph3Sn ⋅ CH3OH moieties are branched along chains according to a syndiotactic organization and via Sn-O-Se connections. From a supramolecular point of view, intermolecular hydrogen bonds established between the selenate groups (uncoordinated oxygen) and the hydroxyl functions (CH3OH) of the pendant groups link the chains together.

"Om Alle Menschen Wel Te Leren Sterven"

1986 ◽  
Vol 66 (2) ◽  
pp. 148-179
Author(s):  
E.J.G. Lips
Keyword(s):  
Point Of View ◽  
Religious Communities ◽  
Original Text ◽  
The Public ◽  
Ars Moriendi ◽  
Text Types ◽  
Dutch Language ◽  
The Masses

AbstractThe genre of the Ars moriendi is by no means a homogeneous one. Indeed, the great textual diversity has more than once attracted the attention. This diversity, caused by various omissions and, more often, extensions in the original text-types, is often considered as the decay of an originally orthodox theological genre. In this essay, manuscripts and printed versions of the Ars moriendi in the Dutch language ( ± 1450-1530) are studied. Instead of considering the omissions and extensions meant above as a decline of the genre, the author attempts to regard them, as the medieval writers may have done, as means to make the texts find their way to the public more easily. Various methods used by the authors of these Artes to reach their public, are examined and their presumable succes is evaluated. It seems that, whereas particularly the older literature assumes an almost infinite public, recent research does not confirm this point of view. For, in spite of explicit remarks addressed to all christians, commerce dictated to the printers a more or less wealthy public. As for the manuscripts, these seem mainly to have had a public of clergy and (female) religious communities. However, considering the existence of a public of listeners, both manuscripts and printed versions had, in an indirect way, their impact on the masses of the christians.

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