Quaternary ammonium cation

In chemistry, quaternary ammonium cations, also known as quats, are positively-charged polyatomic ions of the structure , where R is an alkyl group, an aryl group or organyl group. Unlike the ammonium ion () and the primary, secondary, or tertiary ammonium cations, the quaternary ammonium cations are permanently charged, independent of the pH of their solution. Quaternary ammonium salts or quaternary ammonium compounds (called quaternary amines in oilfield parlance) are salts of quaternary ammonium cations. Polyquats are a variety of engineered polymer forms which provide multiple quat molecules within a larger molecule. Quats are used in consumer applications including as antimicrobials (such as detergents and disinfectants), fabric softeners, and hair conditioners. As an antimicrobial, they are able to inactivate enveloped viruses (such as SARS-CoV-2). Quats tend to be gentler on surfaces than bleach-based disinfectants, and are generally fabric-safe. Synthesis Quate

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Interactions of highly charged polyelectrolytes with monolayers of oppositely charged amphiphiles

Vesela Malinova, Christine Wandrey

Poly(vinylbenzylammonium chloride) (PVBAC) polyelectrolytes possessing defined chain lengths, narrow chain length distributions, uniform charge d., but substituents of different hydrophilicity and size at the quaternary ammonium group were used as model compds. to study the influence of the chain length and the substituent type on the interaction with oppositely charged monolayers. Langmuir monolayers were formed from dimyristoylphosphatidic acid (DMPA). Pressure-area and pressure-time isotherms revealed an increase of both the area per amphiphile mol. and the surface pressure at const. area as a function of time if the polyelectrolyte adsorbs on the amphiphile. The compressibility of the DMPA/PVBAC complex layers is much higher than the compressibility of the DMPA monolayer. Also, the results clearly indicate the influence of the chain length and the substituent type. Larger and more hydrophobic substituents at the quaternary ammonium group significantly increase the area per amphiphile mol., from 0.42 nm2 for the amphiphile up to 0.97 nm2 for the complex. This parameter also increases with decreasing chain length. Incorporation of the hydrophobic substituents into the monolayer as well as end group effects probably are the reason for the monolayer extension. [on SciFinder (R)]

2004

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Adsorption of charged macromolecules on oppositely charged porous column materials

Vesela Malinova, Christine Wandrey

A family of cationic polyelectrolytes possessing defined chain lengths, narrow chain length distributions, uniform charge d., but substituents of different hydrophilicity at the quaternary ammonium group served as model compds. for adsorption studies. These studies quant. revealed that polymer characteristics and electrostatic parameters affect the adsorption behavior on oppositely charged porous column materials. The presence of electrostatic exclusion, in addn. to size exclusion, was proved comparing mol., electrostatic and geometrical parameters. The dominance of electrostatic effects could be concluded evaluating the relation between mol. and electrostatic dimensions. The results provide a contribution how to est. the threshold for electrostatic exclusion from pores as a function of dimensions and exptl. conditions. [on SciFinder (R)]

2004

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Direct Photoexcitation of Ethynylbenziodoxolones: An Alternative to Photocatalysis for Alkynylation Reactions**

Stephanie Grace Elizabeth Amos, Diana Cavalli, Franck Le Vaillant, Jérôme Waser

Ethynylbenziodoxolones (EBXs) are commonly used as radical traps in photocatalytic alkynylations. Herein, we report that aryl-substituted EBX reagents can be directly activated by visible light irradiation. They act as both oxidants and radical traps, alleviating the need for a photocatalyst in several reported EBX-mediated processes, including decarboxylative and deboronative alkynylations, the oxyalkynylation of enamides and the C-H alkynylation of THF. Furthermore, the method could be applied to the synthesis of alkynylated quaternary centers from tertiary alcohols via stable oxalate salts and from tertiary amines via aryl imines. A photocatalytic process using 4CzIPN as an organic dye was also developed for the deoxyalkynylation of oxalates.

WILEY-V C H VERLAG GMBH2021

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Tensioactif

vignette|Le rôle du tensioactif dans la liaison entre particules magnétiques et solvant. Un tensioactif ou agent de surface ou surfactant (mot emprunté à l'anglais) est un composé qui modifie la tensi

Hydroxyde

Un hydroxyde est un sel métallique de formule générique (comme NaOH, KOH, , ...), constitué d'un cation métallique et d'un ou de plusieurs anions hydroxydes. L'anion hydroxyde (ou hydroxyle) se ré

Amine (chimie)

vignette|100px|Structure de l'ammoniac. Une amine est un composé organique dérivé de l'ammoniac dont au moins un atome d'hydrogène a été remplacé par un groupe carboné. Si l'un des atomes de carbone l

CH-112: Organic chemistry

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MSE-101(a): Materials:from chemistry to properties

Ce cours permet l'acquisition des notions essentielles relatives à la structure de la matière, aux équilibres et à la réactivité chimique en liaison avec les propriétés mécaniques, thermiques, électriques et magnétiques des matériaux.

CH-424: Supramolecular chemistry

The course provides an introduction to supramolecular chemistry. In addition, current trends are discussed using recent publications in this area.