ammonium group

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ammonium group,

in chemistry, a positively charged nitrogen atom joined by single bonds to four other atoms or groups. The simplest ammonium group, NH4+, is formed by protonationprotonation
, in chemistry, addition of a proton to an atom, molecule, or ion. The proton is the nucleus of the hydrogen atom; the positive hydrogen ion, H+, consists of a single proton.
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 of ammoniaammonia,
chemical compound, NH3, colorless gas that is about one half as dense as air at ordinary temperatures and pressures. It has a characteristic pungent, penetrating odor.
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, NH3, e.g., by its reaction with hydrogen chloride, HCl, to form ammonium chloride, NH4Cl, an ammonium compound. Organic ammonium compounds are formed by the reaction of an alkyl halide with an amine (see amino groupamino group,
in chemistry, functional group that consists of a nitrogen atom attached by single bonds to hydrogen atoms, alkyl groups, aryl groups, or a combination of these three. An organic compound that contains an amino group is called an amine.
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), for example, ethyl chloride, C2H5Cl, reacts with triethylamine, (C2H5)3N, to form tetraethyl ammonium chloride, (C2H5)4N+Cl. They are also formed by reaction of an amine with a mineral acid or by reaction of an alkyl halide with ammonia.
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References in periodicals archive ?
14 ppm was attributed to nine protons of the three methyl substitutes on the quaternary ammonium group.
Permeability factors may limit the protective effect of ACh or choline because both of these contain quaternary ammonium groups, just like HC-3.
Ion exchange functional groups, such as sulfonic acid groups for cation exchange and quaternary ammonium groups for anion exchange, were distributed both on the resin surface and throughout the polymer.
A long, flat molecule -- a diammonium salt with a central, hydrophobic (water-avoiding) region flanked by charged ammonium groups -- serves as a template for the complex.
Thus, chemical modification of chloromethylated polysulfone by the quaternization of ammonium groups is an efficient method for increasing the hydrophilicity.