Methylpyridinium is an ion with the formula . It is the ''N''-
methylated
Methylation, in the chemical sciences, is the addition of a methyl group on a substrate, or the substitution of an atom (or group) by a methyl group. Methylation is a form of alkylation, with a methyl group replacing a hydrogen atom. These term ...
derivative of
pyridine
Pyridine is a basic (chemistry), basic heterocyclic compound, heterocyclic organic compound with the chemical formula . It is structurally related to benzene, with one methine group replaced by a nitrogen atom . It is a highly flammable, weak ...
. It confers no color to its salts. The ion is classified as a
quaternary ammonium ion
In organic 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 ...
.
Preparation and occurrence
Methylpyridinium is prepared by treating pyridine with
dimethylsulfate
Dimethyl sulfate (DMS) is a chemical compound with formula (CH3O)2SO2. As the diester of methanol and sulfuric acid, its formula is often written as ( CH3)2 SO4 or Me2SO4, where CH3 or Me is methyl. Me2SO4 is mainly used as a methylating agent i ...
:
:
It is found in some
coffee
Coffee is a beverage brewed from roasted, ground coffee beans. Darkly colored, bitter, and slightly acidic, coffee has a stimulating effect on humans, primarily due to its caffeine content, but decaffeinated coffee is also commercially a ...
products.
It is not present in unroasted coffee beans, but is formed during roasting from its precursor chemical,
trigonelline
Trigonelline is an alkaloid with chemical formula . It is a zwitterion formed by the methylation of the nitrogen atom of niacin (vitamin B3). Trigonelline is a product of niacin metabolism that is excreted in the urine of mammals.
Trigonelline oc ...
.
Ionic liquid
The chloride salt of ''N''-methylpyridinium behaves as an
ionic liquid
An ionic liquid (IL) is a salt (chemistry), salt in the liquid state at ambient conditions. In some contexts, the term has been restricted to salts whose melting point is below a specific temperature, such as . While ordinary liquids such as wate ...
. Mixtures of that salt and
zinc chloride
Zinc chloride is an Inorganic chemistry, inorganic chemical compound with the chemical formula, formula ZnCl2ยท''n''H2O, with ''n'' ranging from 0 to 4.5, forming water of hydration, hydrates. Zinc chloride, anhydrous and its hydrates, are colo ...
have been characterised over the temperature range .
See also
*
Pyridinium
Pyridinium refers to the cation . It is the conjugate acid of pyridine. Many related cations are known involving substituted pyridines, e.g. picolines, lutidines, collidines. They are prepared by treating pyridine with acids.
As pyridine is often ...
*
4-Caffeoyl-1,5-quinide
4-Caffeoyl-1,5-quinide (4-caffeoylquinic-1,5-lactone or 4-CQL) is found in roasted coffee beans. It is formed by lactonization of 4-''O''-caffeoylquinic acid during the roasting process.
:
It is reported to possess opioid antagonist properties i ...
*
References
Pyridinium compounds
Ionic liquids
Cations
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