Pyrroles dimethylaminobenzaldehyde

Pyrrolealdehyde has been prepared from pyrrole, chloroform, and potassium hydroxide from pyrrolemagnesium iodide and ethyl, propyl, or isoamyl formate and, by the method here described, from pyrrole, phosphorus oxychloride, and dimethylformamide. Smith has suggested a possible intermediate in this process. The method has also been applied to substituted pyrroles and is similar to that described in this series for the preparation of -dimethylaminobenzaldehyde from di-methylaniline. ... 

Dimethoxytetrahydrofuran forms pyrrole derivatives with primary amines, these derivatives then condense with 4-dimethylaminobenzaldehyde in acid milieu to yield colored products [1] ... 

All acid-catalyzed electrophilic substitution reactions are held by Treibs to occur by way of the distinct reactive species (23), thus the very greatly accelerated interaction of pyrrole and formaldehyde in acid solution involves attack of neutral formaldehyde on (23). Another example is the interaction of 2,3,4,6-tetramethylpyrrole with p-dimethylaminobenzaldehyde in acid solution, for which the following reaction (Scheme 2) is given,(23a) being presumably intended... 

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. 

In most porphyrias, excess metabolites can be detected in urine. Less polar porphyrins (i.e., coproporphyrins and protoporphyrin) are detectable in feces as they are excreted by the bile. The apolar protoporphyrin is eventually only detectable in blood. Porphyrins can easily be detected and measured by their intense fluorescence in mineral acids. The excitation wavelength is around 404 nm, and emission at about 615 nm. ALA is derivatized to a pyrrole and both, ALA and PBG, are detected by dimethylaminobenzaldehyde (DMAB), as described by Mauzerall and Granick [7]. 

The Ehrlich reagent, developed originally for the colorimetric assay of pyrrole derivatives, was shown by Ehrlich to give a color with certain glycoproteins, with and without prior alkali treatment (3). The reagent consists of dimethylaminobenzaldehyde in strong hydrochloric acid. This assay later became the basis for the Morgan-Elson reaction for the deter-... 

The most specific and frequently used assay to quantify 2-deoxy-2-amino sugars employs the condensation of the carbohydrate with 2,4-pentanedione in basic solution. The product (a pyrrole derivative) is then reacted with p-dimethylaminobenzaldehyde to form a chromogen that has a maximum absorbance at 530 nm (Fig. 11-2). Although both 6-deoxy-6-amino and 3-deoxy-3-amino sugars can also be analyzed using the Elson-Morgan reaction, the chromogens... 

J. F. Liebman and R. M. Pollack, in The Chemistry of Enones (Eds. S. Patai and Z. Rappoport), Wiley, Chichester, 1989. Buried enones in this chapter included pyrrole-2-aldehyde, 4-pyridone, 2-aminotropone, p-dimethylaminobenzaldehyde, indigotin and both methylphaeo-phorbide a and b. These compounds may also be recognized as buried enamines. 

Color reactions Boric acid (hydroxyquinones). Dimethylaminobenzaldehyde (pyrroles). Ferric chloride (enols, phenols). Haloform test. Phenylhydrazine (Porter-Silber reaction). Sulfoacetic acid (Liebermann-Burchard test). Tetranitromethane (unsaturation). Condensation catalysts /3-Alanine. Ammonium acetate (formate). Ammonium nitrate. Benzyltrimethylammonium chloride. Boric acid. Boron trilluoride. Calcium hydride. Cesium fluoride. Glycine. Ion-exchange resins. Lead oxide. Lithium amide. Mercuric cyanide. 3-Methyl-l-ethyl-2-phosphoiene-l-oxlde. 3-Methyl-1-phenyi-3-phoipholene-1-oxide. Oxalic acid. Perchloric acid. Piperidine. Potaiaium r-butoxIde. Potassium fluoride. Potassium... 

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. 

Under standard conditions, a 6% solution of p-dimethylaminobenzaldehyde in mineral acid is added to the sample, and the mixture is heated for 30 min. at 100 . The developed coloration, with Xmax at 530 and 565 m i, is then read at 565 m/i it is stable for several hours. The method will give incorrect results in the presence either of pyrrole derivatives or of alkali-treated mucopolysaccharides. 

Condensations with aromatic aldehydes carrying appropriate electron-releasing substituents produce cations that are sufficiently stabilised by mesomerism to be isolated. Such cations are coloured the reaction with p-dimethylaminobenzaldehyde is the basis for the classical Ehrlich test, deep red/violet colours being produced by pyrroles (and also by furans and indoles) that have a free nuclear position. Under appropriate conditions one can combine four mole equivalents of pyrrole and four of an aldehyde to produce a... 

Pergolide mesylate contains an indole ring system. Indole derivatives with free 2- or 3- positions in the pyrrole ring condense with p-dimethylaminobenzaldehyde in a sulfuric acid solution to produce a deep purplish blue color (Neubauer Rhode Reaction). Since the more reactive 3-position in pergolide mesylate is blocked, the condensation reaction of the less reactive 2-position results in a slow color development. The addition of ferric chloride catalyzes this color reaction. 

The formation of pyrrole rings as a result of the thermal destruction of polyamides is also indicated by the positive Erlich reaction (red color with N, N -dimethylaminobenzaldehyde hydrochloride) the initial polyamide does not give this reaction [8, 9, 19, 24]. 

Pyrrole derivatives s. 11, 153 p-Dimethylaminobenzaldehyde Amines from a-aminocarboxylic acids s. 13, 142... 

Fundamentally similar to pyrromethene formation are two of the classical colour reactions associated with pyrroles. The redness produced by pyrroles with an acid-moistened pine shaving is due to reaction with aldehydes in the wood, but it is not specific for pyrroles " . Ehrlich s reaction depends on the formation of coloured products by the reaction of a pyrrole with j -dimethylaminobenzaldehyde in acid solution. The nature of the reaction is indicated by the isolation of a salt of the cation (26) after treatment of (27) with the Ehrlich reagent, a carboxyl group being eliminated (26) gives red solutions, the disodium salt of the derived free base produces yellow solutions, and treatment of (26) with excess acid the colourless di-protonated salt . ... 

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