Search results
Results From The WOW.Com Content Network
In chemistry, the haloform reaction (also referred to as the Lieben haloform reaction) is a chemical reaction in which a haloform (CHX 3, where X is a halogen) is produced by the exhaustive halogenation of an acetyl group (R−C(=O)CH 3, where R can be either a hydrogen atom, an alkyl or an aryl group), in the presence of a base.
The structure of the fuchsin dye. The Schiff test is an early organic chemistry named reaction developed by Hugo Schiff, [1] and is a relatively general chemical test for detection of many organic aldehydes that has also found use in the staining of biological tissues. [2]
Ketones give positive results in Brady's test, the reaction with 2,4-dinitrophenylhydrazine to give the corresponding hydrazone. Ketones may be distinguished from aldehydes by giving a negative result with Tollens' reagent or with Fehling's solution. Methyl ketones give positive results for the iodoform test. [7]
Tollens' test for aldehyde: left side positive (silver mirror), right side negative Ball-and-stick model of the diamminesilver(I) complex. Tollens' reagent (chemical formula ()) is a chemical reagent used to distinguish between aldehydes and ketones along with some alpha-hydroxy ketones which can tautomerize into aldehydes.
Iodoform stored in an ampoule. Iodoform (also known as triiodomethane) is the organoiodine compound with the chemical formula C H I 3.It is a pale yellow, crystalline, volatile substance, with a penetrating and distinctive odor (in older chemistry texts, the smell is sometimes referred to as that of hospitals, where the compound is still commonly used) and, analogous to chloroform, sweetish taste.
Generally, Benedict's test detects the presence of aldehyde groups, alpha-hydroxy-ketones, and hemiacetals, including those that occur in certain ketoses. In example, although the ketose fructose is not strictly a reducing sugar, it is an alpha-hydroxy-ketone which results to a positive test because the base component of Benedict converts it ...
Another method is the Takai olefination which uses iodoform and chromium(II) chloride to make vinyl iodide from aldehyde with high stereoselectivity for E geometry. [27] For high stereoselectivity for Z geometry, Stork-Zhao olefination proceeds by Wittig-like reaction.
One of the more well-known uses of organoiodine compounds is the so-called iodoform test, where iodoform (CHI 3) is produced by the exhaustive iodination of a methyl ketone (or another compound capable of being oxidised to a methyl ketone), as follows: [26]