Ehrlich’s reagents

Ehrlich s reagent as 4-(dimethylamino)-benzaldehyde — hydrochloric acid and... 

It can be concluded from the publications of Rohde [2] and Freund and Lebach [3, 4] that it was Ehrlich who first suggested the use of 4-(dimethylamino)-benzalde-hyde in the presence of hydrochloric acid for color reactions with methylketols that was found also to apply to indole derivatives [S]. Auterhoff [6] designated a reagent for urobilinogen, consisting of a solution of 2 g 4-(dimethylamino)-benzaldehyde in 20 percent hydrochloric acid, correctly as Ehrlich s solution. Hence, it is essentially correct to refer to all reagents which contmn these components as Ehrlich s reagent. 

Pyrolizidine alkaloids Heliotropium crassifolium SiOj CHCI3 + MeOH + NH3 aqueous DragendorlTs reagent Ehrlich s reagent Isolation 15... 

Fischbach and Levine described the use of Ehrlich s reagent as an identity test for gramicidin125. 

Bilirubin Diazotized sulphanilic acid (Ehrlich s Reagent) 540... 

Hydroxyproline assay. Hydroxyproline was determined according to Jamall et al. (1981). The assay employs p-dimethylaminobenzaldehyde (Ehrlich s reagent), which forms colored products with pyrroles originating from hydroxyproline oxidation. The values thus determined for hydroxyproline mass were multiplied by 8.0 to obtain the corresponding collagen mass. 

Ehrlich s reagent add 2.5 g p-DMAB to a mixture of 50 ml concentrated acetic acid, 24.5 ml perchloric acid, and 4 ml mercury chloride/trichloroacetic acid solution. 

The 3-vinylpyrroles (366 X = H or C02H) also react with electrophiles. No products were isolated, but it was suggested that the blue colouration produced upon the acid-catalyzed reaction with Ehrlich s reagent was due to the formation of (370) and that it was identical with that of the product obtained from the reaction of the trisubstituted pyrrole and the cinnamaldehyde. Similarly, the red colouration obtained from the reaction of (366 X = H or C02H) with diazotized sulfanilic acid was ascribed to the formation of (371) <58LA(611)205). 

Indolizine, like many of its derivatives, is air and light sensitive. It gives a colour reaction with Ehrlich s reagent and is highly fluorescent. 

Detection is made in UV light. The yellow fluorescence of tetracyclines and their epimers in UV light is greatly enhanced by exposing the paper to ammonia vapours. They may also be detected by Ehrlich s reagent or by starch-iodine following N-chlorination (137). 

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