Why purple coloured ring formed in rothera's test?

Answer 1

Well, honey, that purple ring forms in Rothera's test because of the reaction between the ketone group in the compound and the reagent ammonium molybdate. It's like a chemical love story, creating a beautiful purple color as a result. So, next time you see that ring, just remember it's all about chemistry doing its thing.

Answer 2

Rothera's test is useful for qualitative detection of ketone bodies in urine.Ketone bodies are acetone,acetoacetic acid and Beta-hydroxy butyric acid.Among the three,Rothera's test detects only first two.For detection of Beta-hydroxy butyric acid the urine sample is heated to drive out any acetone or acetoacetic acid.Then,hydrogen peroxide is added to oxidise Beta-hydroxy butyric acid to acetoacetic acid which is then detected by the conventional Rothera's test.However,as the three ketone bodies tend to occur together such detection of Beta-hydroxy butyric acid is unnecessary in routine practice.Ketone bodies are found in a variety of condition- two most important are Diabetes Mellitus and starvation.Ketone bodies are formed when there is excessive breakdown of fat.Acetyl CoA an intermediate of fat breakdown as well as Kreb's Cycle is formed in excess of what can be utilised in Kreb's Cycle.Hence molecules of ACetyl CoA join with each other to form Ketone bodies in the liver(liver itself is unable to utilise Ketone bodies due to lack of necessary breakdown enzyme for ketone bodies although it contains the synthesising enzymes).Ketone bodies tend to oppose glucose utilisation in brain in diabetics.When ketone bodies accumulate too much it causes Diabetic Ketoacidosis-requires emergency management.Insulin-dependent diabetics are more prone to develop such complications.

Rothera's test is performed in a small test tube.A small amount of urine is taken and it is fully saturated with ammonium salt.Then a drop of sodium nitroprusside is added to it.Finally as in all ring tests-ammonium hydroxide is slowly added by side of test tube.After few seconds a purple ring develops at junction of two liquids-Urine and ammonium hydroxide.The purple ring is due to a complex formed between ketone body and nitroprusside in presence of ammonia.

Answer 3

The purple ring formed in Rothera's test is due to the reaction between ketones and alpha-napthol in the presence of sulfuric acid. This reaction leads to the formation of a violet-colored complex, indicating the presence of ketones in the test sample.