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Indole test positive: appearance of pink layer at top (e.g. Escherichia coli) Like many biochemical tests on bacteria, results of an indole test are indicated by a change in color following a reaction with an added reagent. Pure bacterial culture must be grown in sterile tryptophan or peptone broth for 24–48 hours before performing the test.
Indole is an organic compound with the formula C 6 H 4 CCNH 3. Indole is classified as an aromatic heterocycle. It has a bicyclic structure, consisting of a six-membered benzene ring fused to a five-membered pyrrole ring. Indoles are derivatives of indole where one or more of the hydrogen atoms have been replaced by substituent groups.
The Bischler-Möhlau indole synthesis. Despite its long history, this classical reaction had received relatively little attention in comparison with other methods for indole synthesis, owing to the reactions harsh conditions, poor yields and unpredictable regioselectivity. Recently, milder methods have been developed, including the use of ...
Kovács reagent is a biochemical reagent consisting of isoamyl alcohol, para-dimethylaminobenzaldehyde (DMAB), and concentrated hydrochloric acid.It is used for the diagnostical indole test, to determine the ability of the organism to split indole from the amino acid tryptophan.
The Ehrlich reagent is similar to a number of other indole tests: The van Urk reagent, which uses 0.125 g of p-DMAB, 0.2 mL of ferric chloride solution (25 mg/mL) in 100 mL of 65% sulfuric acid. [9] [10] [11] This is sometimes referred to as the Hofmann reagent or p-DMAB-TS (Test Solution) and gives slightly different colours with different ...
The term "IMViC" is an acronym for each of these tests. "I" is for indole test; "M" is for methyl red test; "V" is for Voges-Proskauer test, and "C" is for citrate test. The lower case "i" is merely for "in" as the Citrate test requires coliform samples to be placed "in Citrate". These tests are useful in distinguishing members of ...
The reaction mechanism [8] of the Bartoli indole synthesis is illustrated below using o-nitrotoluene (1) and propenyl Grignard (2) to form 3,7-dimethylindole (13). The mechanism of the Bartoli indole synthesis. The mechanism begins by the addition of the Grignard reagent (2) onto the nitroarene (1) to form intermediate 3.
The optimized Indole reaction uses 10% Pd/C (3.0 mol%) with 1.1 equivalent of NaOAc, and NMP at 110–130 °C. Monguchi et al. state that their optimized condition of the Larock indole synthesis without LiCl is a more mild, environmentally benign, and efficient strategy for producing indoles.