One methine group (=CH-) replaced by a nitrogen atom.
Pyridine is used as a precursor to agrochemicals and pharmaceuticals and is also an important solvent and reagent. Pyridine is added to ethanol to make it unsuitable for drinking (see denatured alcohol). Pyridine is a basic heterocyclic organic compound with the chemical formula C5 H5 N. It is structurally related to benzene, with one methine group (=CH-) replaced by a nitrogen atom. The pyridine ring occurs in many important compounds, including azines and the vitamins niacin and pyridoxal Ionization. There are two classes of acids: strong acids and weak acids. Note that strong acids and bases are rarely a concern in biochemistry (as they are in general chemistry). Strong acids ionize (break into ions) completely when dissolved in water. In other words, a strong acid is a good proton donor. For example, the strong acid HCl gives up all its protons to water: Weak bases exist in chemical equilibrium much in the same way as weak acids do, with a base dissociation constant (Kb) indicating the strength of the base. For example, when ammonia is put in water, the following equilibrium is set up: Bases that have a large K b will ionize more completely and are thus stronger bases. In chemistry, a weak base is a chemical base that does not ionize fully in an aqueous solution. As Broensted–Brønsted lowry bases are proton, acceptors a weak base may also be defined as a chemical base in which protonation is. Incomplete this results in a relatively pH ph compared to strong. bases The acid illustrated is hydrochloric acid. Pure hydrochloric acid is a gas, but it dissolves easily in water to produce a solution of hydrogen ion and chloride ion. Since nearly all of it is dissociated in water, it is called a strong acid. Acids that do not dissociate completely are called weak acids. Acids and Bases. Atoms can gain or lose electrons in order to form ions in a process called ionization (compounds formed in this way are called ionic compounds). When ionic compounds dissolve in water, their ions separate from one another in a process called dissociation. One interesting feature of water and many other covalent compounds is that they too can dissociate into ion [16.33]. The constant Kb is called the base-dissociation constant, by analogy with the acid-dissociation constant, Ka, for weak acids. The constant Kb always refers to the equilibrium in which a base reacts with H2O to form the conjugate acid and OH – .  B). Benzoic acid is a weak acid that has antimicrobial properties. Its sodium salt, sodium benzoate, is a preservative found in foods, medications, and personal hygiene products. Benzoic acid dissociates in water: The of this reaction is 4.2. In a 0.71 solution of benzoic acid, what percentage of the molecules are ionized? Abstract. The energetics, geometrical structures, ionization process, dissociation channels of pyridine-ammonia (Py⋯NH 3) and the corresponding cation complexes are investigated with ab initio theory. As a simple model system to gain insight into the ionization and dissociation of the hydrogen bond systems of biological macromolecules, we have carried out a detailed examination of the pyridine–ammonia complex as a prototypical example.
https://en.wikipedia.org/wiki/Pyridine http://www.wiley.com/college/pratt/0471393878/student/review/acid_base/4_strong_and_weak.html https://en.wikipedia.org/wiki/Weak_base http://biologycorner.com/worksheets/acids_bases_coloring.html http://wps.prenhall.com/wps/media/objects/3312/3392119/blb1607.html http://www.chegg.com/homework-help/questions-and-answers/pyridine-weak-base-used-manufacture-pesticides-plastic-resins-also-component-cigarette-smo-q1007639 http://www.sciencedirect.com/science/article/pii/S0009261404012795
what does pyridine dissociate into