molisch reaction
A student observes a violet ring form in a test tube during a Molisch reaction.
Noun: A biochemical test used to indicate the presence of carbohydrates (like sugars, starches, or glycoproteins) in a solution. The test is positive when a purple or violet-colored ring forms at the interface of the liquid layers after the sample is treated with alpha-naphthol and concentrated sulfuric acid.
The term is used specifically in biochemistry and analytical chemistry to describe this classic qualitative test. * The Molisch reaction is a general test for all carbohydrates. * A positive Molisch reaction confirms the presence of a carbohydrate in the unknown sample. * The laboratory procedure involves performing the Molisch reaction on the filtrate.
- Molisch's Test: This is the most common alternate name for the procedure. (e.g., "We will use to screen for the presence of polysaccharides.")
- The reaction is named after the Austrian botanist Hans Molisch, who described it.
- Molisch's test (n): A synonymous term for the Molisch reaction.
- Molisch's reagent (n): The chemical reagent, typically a solution of alpha-naphthol in ethanol, used to perform the test.
- Molisch's test
- Alpha-naphthol test (a descriptive synonym based on the reagent used)
The Molisch reaction is a general test. It gives a positive result for a wide range of carbohydrates, including monosaccharides (e.g., glucose), disaccharides (e.g., sucrose), and polysaccharides (e.g., starch). It does not distinguish between them. Other specific tests (like Benedict's test for reducing sugars) are needed for further identification.
A student observes a violet ring form in a test tube during a Molisch reaction.
- biochemical indicator of the presence of carbohydrates in a solution; if carbohydrates are present a violet ring is formed by reaction with alpha-naphthol in the presence of sulfuric acid