protonation


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protonation

(prō`tənā'shən), in chemistry, addition of a protonproton,
elementary particle having a single positive electrical charge and constituting the nucleus of the ordinary hydrogen atom. The positive charge of the nucleus of any atom is due to its protons.
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 to an atom, molecule, or ion. The proton is the nucleus of the hydrogenhydrogen
[Gr.,=water forming], gaseous chemical element; symbol H; at. no. 1; interval in which at. wt. ranges 1.00784–1.00811; m.p. −259.14°C;; b.p. −252.87°C;; density 0.08988 grams per liter at STP; valence usually +1.
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 atom; the positive hydrogen ion, H+, consists of a single proton. An example of protonation is the formation of the ammonium groupammonium 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 protonation of ammonia, NH3, e.g.
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 NH4+ from ammonia, NH3. Protonation often occurs in the reaction of an acid with a base to form a salt (see acids and basesacids and bases,
two related classes of chemicals; the members of each class have a number of common properties when dissolved in a solvent, usually water. Properties
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; saltssalt,
chemical compound (other than water) formed by a chemical reaction between an acid and a base (see acids and bases). Characteristics and Classification of Salts

The most familiar salt is sodium chloride, the principal component of common table salt.
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). Protonation differs from hydrogenationhydrogenation
, chemical reaction of a substance with molecular hydrogen, usually in the presence of a catalyst. A common hydrogenation is the hardening of animal fats or vegetable oils to make them solid at room temperature and improve their stability.
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 in that during protonation a change in charge of the protonated species occurs, whereas the charge is unaffected during hydrogenation.
References in periodicals archive ?
Figures (14.a-c) and (15) depicts a Cole-Cole plot between Z' and Z for pure and protonation PANI.It's evident from this plot that relaxation process differs from the monodispersive Debye process (for which [alpha]=0).
The phenomena of changing the chain conformation into a more straight (linear) one is caused by the oxidizing agent, an additive which is usually an acid providing protons (protonation phenomenon).
Raising the pH can be attributed to protonation of the amino groups present in bacteria [5,39] and also due to the decomposition of thiosulfate [40].
The acid-catalyzed condensation reaction proceeds by an initial protonation of the silanol followed by an [S.sub.N2] displacement reaction at the Si leading to formation of water and regeneration of the acid catalyst as depicted in Figure 12.
Effective CEC decreased under permanent fallow and the arable cropping treatments because of: (I) depletion of SOM (direct effect); and (2) soil acidification, which eliminated some of the remaining exchange sites by protonation of organic functional groups (indirect effect).
According to reaction (5), the acetic acid reacts with water and produces hydronium ion, which accelerates dissolution of chitosan through its protonation [reaction (2)].
Vitamin C is found as the L-ascorbate enantiomer (the cleproton-ated form) in biological systems, as a pH5, or less, is necessary for protonation to form the acid.
At the same time there was no change observed in the protonation degree of polyaniline or in the ratio of protonated quinonoid and benzenoid units.
In this work, we observed for the first time a coexistence of two monomer forms of dimethinemerocyanines in polar solvents and here we show how the relationship between these forms is affected by solvent polarity, dye concentration, and protonation.
The user uploads a PDB file which will automatically be fixed (missing atoms and residues will be added to the protein structure, assuming default protonation states at pH 7).
Despite all this, according to protonation of the thiohydantoin-pyrrolidine fused ring systems in acidic solution, the thiohydantoin-pyrrolidine fused ring systems containing carboxylic acid group (2a-f) may have four acidic centers as carboxyl, enthiol, enol, and amino group.
Wagner, "Complexing and protonation of free-radical imidazolin-1-oxyl and imidazolin-1-oxyl 3-oxide ligands: a magnetic-resonance investigation," Journal of the Chemical Society, Dalton Transactions, no.