Michler's ketone
Encyclopedia
Michler’s ketone is an organic compound
with the formula of [(CH3)2NC6H4]2CO. This electron-rich derivative of benzophenone
is an intermediate in the production of dyes and pigments, for example Methyl violet
. It is also used as a sensitizer. It is named after the German chemist Wilhelm Michler
.
of dimethylaniline
(C6H5NMe2) using phosgene
(COCl2) or equivalent reagents such as triphosgene
(Me = methyl):
The related tetraethyl compound (Et2NC6H4)2CO, also a precursor to dyes, is prepared similarly.
, such as crystal violet
.
Condensation of Michler's ketone with N-phenyl-1-naphthylamine gives the dye Victoria Blue B (CAS#2580-56-5, CI Basic Blue 26), which is used for coloring paper and producing pastes and inks for ballpoint pens.
Michler’s ketone is commonly used as an additive in dyes and pigments as a sensitizer for photoreactions because of its absorption properties. Michler’s ketone is an effective sensitizer provided energy transfer is exothermic
and the concentration of the acceptor is sufficiently high to quench the photoreaction of Michler’s ketone with itself. Specifically Michler’s ketone absorbs intensely at 366 nm and effectively sensitizes photochemical reactions such as the dimerization of butadiene to give 1,2-divinylcyclobutane.
, a dye, is a salt of the iminium cation [(CH3)2NC6H4]2CNH2+. Michler's thione, [(CH3)2NC6H4]2CS, is prepared by treatment of Michler's ketone with hydrogen sulfide
in the presence of acid or sulfideing auramine O.
Organic compound
An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...
with the formula of [(CH3)2NC6H4]2CO. This electron-rich derivative of benzophenone
Benzophenone
Benzophenone is the organic compound with the formula 2CO, generally abbreviated Ph2CO. Benzophenone is a widely used building block in organic chemistry, being the parent diarylketone.-Uses:...
is an intermediate in the production of dyes and pigments, for example Methyl violet
Methyl violet
Methyl violet is a family of organic compounds that are mainly used as dyes. Depending on the amount of attached methyl groups, the color of the dye can be altered. Its main use is as a purple dye for textiles and to give deep violet colors in paint and ink...
. It is also used as a sensitizer. It is named after the German chemist Wilhelm Michler
Wilhelm Michler
Wilhelm Michler was a German chemist. He studied under Hermann von Fehling and Victor Meyer in Stuttgart and followed Meyer to the ETH Zurich in 1871. Michler became Professor at the ETH Zurich in 1878...
.
Synthesis
The ketone is prepared today as it was originally by Michler using the Friedel-Crafts acylationAcylation
In chemistry, acylation is the process of adding an acyl group to a compound. The compound providing the acyl group is called the acylating agent....
of dimethylaniline
Dimethylaniline
N,N-Dimethylaniline is an organic chemical compound, a substituted derivative of aniline. It consists of a tertiary amine, featuring dimethylamino group attached to a phenyl group. This oily liquid is colourless when pure, but commercial samples are often yellow...
(C6H5NMe2) using phosgene
Phosgene
Phosgene is the chemical compound with the formula COCl2. This colorless gas gained infamy as a chemical weapon during World War I. It is also a valued industrial reagent and building block in synthesis of pharmaceuticals and other organic compounds. In low concentrations, its odor resembles...
(COCl2) or equivalent reagents such as triphosgene
Triphosgene
Triphosgene is a chemical compound that is used as a safer substitute for phosgene, because at room temperature it is a solid crystal, as opposed to phosgene which is a gas. Triphosgene crystals decompose at around 130 °C, although, the decomposition temperature of impure samples can be much lower...
(Me = methyl):
- COCl2 + 2 C6H5NMe2 → (Me2NC6H4)2CO + 2 HCl
The related tetraethyl compound (Et2NC6H4)2CO, also a precursor to dyes, is prepared similarly.
Uses
Michler’s ketone is an intermediate in the synthesis of dyes and pigments for paper, textiles, and leather. Condensation with various aniline derivatives gives several of the dyes called methyl violetMethyl violet
Methyl violet is a family of organic compounds that are mainly used as dyes. Depending on the amount of attached methyl groups, the color of the dye can be altered. Its main use is as a purple dye for textiles and to give deep violet colors in paint and ink...
, such as crystal violet
Crystal violet
Crystal violet or Gentian violet is a triarylmethane dye. The dye is used as a histological stain and in Gram’s method of classifying bacteria. Crystal violet has antibacterial, antifungal, and anthelmintic properties and was formerly important as a topical antiseptic...
.
Condensation of Michler's ketone with N-phenyl-1-naphthylamine gives the dye Victoria Blue B (CAS#2580-56-5, CI Basic Blue 26), which is used for coloring paper and producing pastes and inks for ballpoint pens.
Michler’s ketone is commonly used as an additive in dyes and pigments as a sensitizer for photoreactions because of its absorption properties. Michler’s ketone is an effective sensitizer provided energy transfer is exothermic
Exothermic
In thermodynamics, the term exothermic describes a process or reaction that releases energy from the system, usually in the form of heat, but also in the form of light , electricity , or sound...
and the concentration of the acceptor is sufficiently high to quench the photoreaction of Michler’s ketone with itself. Specifically Michler’s ketone absorbs intensely at 366 nm and effectively sensitizes photochemical reactions such as the dimerization of butadiene to give 1,2-divinylcyclobutane.
Related compounds
Auramine OAuramine O
Auramine O, also called Basic yellow 2, Pyocatanium aureum, aizen auramine, Pyoktanin Yellow, Canary Yellow, Pyoktanin, or C.I. 41000, is a diarylmethane dye used as a fluorescent stain. In its pure form, Auramine O appears as yellow needle crystals...
, a dye, is a salt of the iminium cation [(CH3)2NC6H4]2CNH2+. Michler's thione, [(CH3)2NC6H4]2CS, is prepared by treatment of Michler's ketone with hydrogen sulfide
Hydrogen sulfide
Hydrogen sulfide is the chemical compound with the formula . It is a colorless, very poisonous, flammable gas with the characteristic foul odor of expired eggs perceptible at concentrations as low as 0.00047 parts per million...
in the presence of acid or sulfideing auramine O.