Hydrogen bond acidic chemical structures

Fig. 12.9. Structure and relative energies of four modes of hydrogen bonding in transition structures for epoxidation of 2-propen-l-ol by peroxyformic acid. Relative energies are from B3I.YP/6-311G -level computations with a solvation model for CH2C12, e = 8.9. Reproduced from / Org. Chem., 64, 3853 (1999), by permission of the American Chemical Society.

Chemoselective hydrogen-bonded acid polymers are at the heart of many electronic nose chemical point detection sensor systems. These polymers selectively adsorb chemical agents or explosives over extended periods of time (minutes, hours, days). Relatively thick polymer films and/or hyperporous structures allow rapid vapor sorption. Material properties are selected to allow vapor sorption, but not desorption, at ambient conditions. Heating allows the trapped agent to be released for analyses. 

Some anthraquinone-sulphenic and -disulphenic acids and 1-metbyl-uracil-4-sulphenic add have been prepared by different routes . In these compounds intramolecular hydrogen-bonded and tautomeric structures are suggested to stabilize the sulphenic derivatives . Chemical and n.m.r. evidence for the existence of an aliphatic sulphenic acid in the... 

For crosslinked starch materials, physical adsorption in the polymer structure and chemisorption of the pollutant via hydrogen bonding, acid-base interactions, complexation and/or ion exchange are both involved in the sorption process [42, 43]. In most cases, though a combination of these interactions was proposed to explain adsorption mechanisms, the efficiency and the selectivity of these adsorbents are mainly attributed to their chemical network. 

It is a lipophilic compound which removes intercellular lipids that are covalently linked to the cornified envelope surrounding epithelial cells [3]. It also enhances penetration of other agents. Resorcinol (m-dihydroxy benzene) is structurally and chemically similar to phenol. It disrupts the weak hydrogen bonds of keratin [4]. Lactic acid is an alpha hydroxy acid which causes corneocyte detachment and subsequent desquamation of the stratum corneum [5]. 

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