title: Product in indole detection by Ehrlich's reagent.
abstract: Ehrlich's reagent (p-dimethylaminobenzaldehyde [DMAB, 1] in 95% EtOH with HCl as catalyst) was employed in spot tests of indoles, providing a diagnosis of, for example, liver diseases, hemolytic processes, occlusion of the common bile duct, and carcinoid syndrome. Although the reagent has been widely used for more than a century, it is not clear how many indole molecules react with a DMAB molecule and whether the reaction takes place at the α- or β-position of the indole molecule. Research here shows that the reaction of DMAB (1) with indole (2) in a 1:2 ratio gives β-bis(indolyl)methane (3). The reaction occurs at the β-position of indole under the conditions of the Ehrlich test, as confirmed by the crystal structure of 3.
authors.affiliation: Department of Chemistry, University of Tennessee, Knoxville, TN 37996, USA.
authors.forename: Adam C
authors.initials: AC
authors.lastname: Lamb
authors.affiliation: Department of Chemistry, University of Tennessee, Knoxville, TN 37996, USA.
authors.forename: Roberto A
authors.initials: RA
authors.lastname: Federico-Perez
authors.affiliation: Department of Chemistry, University of Tennessee, Knoxville, TN 37996, USA. Electronic address: xue@utk.edu.
authors.forename: Zi-Ling
authors.initials: ZL
authors.lastname: Xue
mesh_terms: D001547:Benzaldehydes / Q000737:chemistry*; D007211:Indoles / Q000032:analysis* / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation
chemical_list: D001547:Benzaldehydes; D007211:Indoles; C030374:indole; C510241:p-dimethylaminobenzaldehyde
keywords: Ehrlich reaction; Indole; β-Position of indole