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Quaternary ammonium cation. The R groups may be the same or different alkyl or aryl groups. Also, the R groups may be connected. In organic chemistry, quaternary ammonium cations, also known as quats, are positively-charged polyatomic ions of the structure [NR 4] +, where R is an alkyl group, an aryl group [1] or organyl group.
In another use of the term in organic chemistry, a quaternary compound is or has a cation consisting of a central positively charged atom with four substituents, especially organic (alkyl and aryl) groups, discounting hydrogen atoms. [1] The best-known quaternary compounds are quaternary ammonium salts, having a nitrogen atom at the center. [2]
Ammonium is a modified form of ammonia that has an extra hydrogen atom. It is a positively charged ( cationic ) molecular ion with the chemical formula NH + 4 or [NH 4 ] + . It is formed by the addition of a proton (a hydrogen nucleus) to ammonia ( NH 3 ).
Tetramethylammonium (TMA) is the simplest quaternary ammonium cation. It has the chemical formula [Me 4 N] + and consists of four methyl groups (−CH 3, denoted Me) attached to a central nitrogen atom. The cation is isoelectronic with neopentane (Me 4 C). It is positively-charged and can only be isolated in association with a counter-ion.
The oldest-known onium ion, and the namesake for the class, is ammonium, NH + 4, the protonated derivative of ammonia, NH 3. [ 1 ] [ 2 ] The name onium is also used for cations that would result from the substitution of hydrogen atoms in those ions by other groups, such as organic groups, or halogens; such as tetraphenylphosphonium , (C 6 H 5 ...
Ammonia forms 1:1 adducts with a variety of Lewis acids such as I 2, phenol, and Al(CH 3) 3. Ammonia is a hard base (HSAB theory) and its E & C parameters are E B = 2.31 and C B = 2.04. Its relative donor strength toward a series of acids, versus other Lewis bases, can be illustrated by C-B plots.
Quaternary ammonium compounds are positively charged polyatomic ions of the structure NR 4 + with R being alkyl or aryl groups. The R groups may also be connected. The R groups may also be connected. Wikimedia Commons has media related to Quaternary ammonium compounds .
Like other quaternary ammonium cations, TPA is prepared by the alkylation of the corresponding ammonia analogue, tripropylamine. Treatment of the amine with a primary propyl halide such as n-bromopropane yields the corresponding TPA halide salt in a Menshutkin reaction: (C 3 H 7) 3 N + C 3 H 7 Br → (C 3 H 7) 4 N + Br −
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