Dioxetanes

1,2-dioxetane

1,3-dioxetane

Dioxetanes are heterocyclic organic chemical compounds that consist of a four-membered ring that has two carbon and two oxygen atoms. The 1,2-dioxetane is thus an organic peroxide , whereas 1,3-dioxetane is a cyclic acetal .

History and biological meaning

A dioxetanone is unstable and decomposes with splitting off of CO ₂ . This creates a ketone in the electronically excited state, which in turn emits energy as light.

Some naturally occurring 1,2-dioxetanes or their α-keto derivatives ( dioxetanones , α-peroxy lactones ) are the cause of bioluminescence . In the 1960s, biochemists came to the conclusion that these compounds in fireflies (including fireflies , Lampyridae , English fireflies ) and other creatures that bioluminescence showed, due to instability, a "running" deposits possess. Then in 1968 the first example of a stable dioxetane was found at the University of Alberta at Edmonton . This 3,3,4-trimethyl-1,2-dioxetane dissolves in benzene with a yellow color . After the solution was heated to 333 Kelvin (60 ° C.), the substance decomposed slowly and not - as expected - explosively to acetone and acetaldehyde with the emission of pale blue light.

The second example of a dioxetane, the symmetrical 3,3,4,4-tetramethyl-1,2-dioxetane, was presented shortly thereafter. The yellow crystals of the substance sublimated even when stored in the refrigerator. The solution in benzene also slowly emitted blue light with decomposition. The color of the emitted light could be changed by suitable substitution with compounds that fluoresce under UV light . Since the 3,3,4,4-tetramethyl-1,2-dioxetane became the object of study for many scientists to elucidate the mechanisms of bioluminescence, this soon became one of the best-studied symmetrical compounds worldwide.

presentation

The biosynthesis of dioxetanes and dioxetanones takes place from a luciferin , which is usually a derivative of a nitrogen-containing polycycle that contains imidazole as a structural element. The organisms convert this luciferin with molecular oxygen, in the presence of Ca ²⁺ ions, via special, species-specific luciferases to form the light-emitting end product. On a laboratory scale, dioxetanes can be prepared from cis -2-butene derivatives such as 2,3-dimethyl-2-butene by reaction with oxygen or with hydrogen peroxide and bromine and subsequent cyclization of the hydroperoxide formed with a base .

use

Luminescent jewelry such as bracelets, necklaces and rings contain artificial derivatives of dioxetanes, which also contain a carbonyl group ; these dioxetanones - like 1,2-dioxetanedione - decompose with the elimination of carbon dioxide and light emission. Other dioxetanes are used in clinical analysis to detect the lowest concentrations of body fluids (such as blood ). Dioxetanes can also be used in appropriately structured detection systems together with luciferases for the highly specific qualitative and quantitative detection of ATP (detection limit 10 ⁻¹¹ mol ), NADH and oxygen that is suitable for minimal quantities .

See also

• Oxetane

Individual evidence

1. ↑ Karl R. Kopecky, Cedric Mumford: Luminescence in the thermal decomposition of 3,3,4-trimethyl-1,2-dioxetane . In: Canadian Journal of Chemistry . 47 (4), 1969, p. 709, doi : 10.1139 / v69-114 .
2. ^ Karl R. Kopecky, John E. Filby, Cedric Mumford, Peter A. Lockwood, Jan-Yih Ding: Preparation and Thermolysis of some 1,2-dioxetanes . In: Canadian Journal of Chemistry . 53 (8), 1975, p. 1103, doi : 10.1139 / v75-154 .
3. ↑ T. Lindel: Heterocyclenchemie ( Memento of the original from March 5, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. (PDF; 4.8 MB), TU Braunschweig 
4. ↑ US Patent No. 5,330,900 to Tropix Inc.
5. ^ Wissenschaft-Online-Lexika: Entry on luciferases in the Lexikon der Chemie , accessed April 2, 2008.