P-Dimethylaminobenzaldehyde Ehrlich’s reagent

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. 

The presence of an a-free pyrrole attached to the native HMBS was also demonstrated, both in Cambridge and Southampton, by treatment with Ehrlich s reagent, acidic p-dimethylaminobenzaldehyde [30, 33]. This initially gave the UV/visible absorbance at 564 nm, typical of the Ehrlich product from an a-free pyrrole, but the spectrum then changed to one at 495 nm, typical of a dipyrromethene, indicating that the cofactor is in fact a dipyrromethane (e. g. 32), as shown in Scheme 11 and tautomerisation of the initial product 33 occurs to give 34. 

Dimethylaminobenzaldehyde N,N-Dimethyl-4-aminobenzaldehyde. See p-Dimethylaminobenzaldehyde p-Dimethylaminobenzaldehyde CAS 100-10-7 EINECS/ELINCS 202-819-0 Synonyms 4-Dimethylaminobenzaldehyde N,N-Dimethyl-4-aminobenzaldehyde 4-Dimethylaminobenzenecarbonal Ehrlich s reagent p-FormyIdimethylaniline Empiricai C9H11NO Formuia C6H4[N(CH3)2]CHO Properties Yel. cryst. solid sol. in alcohol, ether, chloroform, acetic acid, other org. soivs. si. sol. in water m.w. 149.21 m.p. 73 C b.p. 176-177 C (17 mm)... 

Ehrlich s Test Ehrlich s reagent, p-dimethylaminobenzaldehyde (p-DMAB) in ethanol with HCl, works through the formation of a stable carbocation or ion by condensation (Figure This reagent is used principally for the de-... 

B. 5% soln. of p-dimethylaminobenzaldehyde in hydrochloric acid-methanol (5 100) (Ehrlich s reagent)... 

The isolation of PBG by Westall (7) and the determination of its structure by Cookson and Rimington (77, 78) were crucial steps in the detailed description of the biosynthesis of porph3rrin. PBG (Fig. 11) was first detected by Sachs 88) in the urine of patients with acute porphyria, since the urine turned red with Ehrlich s reagent (p-dimethylaminobenzaldehyde in acid solution). This red compound was insoluble in CHClj thus differentiating it from urobilinogen. Waldenstrom (83) recognized PBG as a distinct entity. It has been also found in the liver and feces 84,85) of these patients. 

Qualitatively, the presence of the nonulosaminic acids is best indicated by the brilliant-red coloration formed on addition of an acidic solution of p-dimethylaminobenzaldehyde (the so-called direct Ehrlich reaction ), and by the bright-purple coloration which develops upon boiling with Bial s reagent for several minutes at 100°. In addition, the nonulosaminic acids give a blue-violet coloration with Dische s diphenylamine reagent for deoxypentoses and a positive reaction in the tryptophan-perchloric acid test. Since no single one of these color reactions is absolutely specific for a nonulosaminic acid, it is advisable to carry out at least two of these for a qualitative analysis. For quantitative determinations, all four reactions have been employed, using either A/ -acetylneuraminic acid (m. p., 183-185° [a] —32.0°) or methoxyneuraminic acid [m. p., 200° (dec.) [a]o —55.0°] as colorimetric standards. 

Benzylidine Test.— The solutionis acidified with a few drops of HCl, and then a few drops of Ehrlich s aldehyde reagent (3 per cent, p-dimethylaminobenzaldehyde in 20 per cent. HCl) are added. An intense yellow colour develops if urea be present. 

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