Vitali reaction

The aromatic nitro compounds make up another group of substances. These can also be formed directly on the TLC layer as a result of the frequently used Vitali reaction [24]. They are detected — as shown in Fig. 21 — by reduction and coupling to azo dyes. 

Allport and Wilson (75) have also adopted Vitalis reaction for the rapid determination of the alkaloids in belladonna and stramonium. 

Z). stramonium Ly. esculentum hyoscyamine/solanine a) No mydriasis, Vitali reaction, or auri- chloride. b) No mydriasis. a) b) 76 75... 

Atropa belladonna S. tuberosum hyoscyamine/ solanine a) a) No mydriasis or Vitali reaction in tubers 79... 

A. belladonna Ly. esculentum hyoscyamine /solanine a) Vitali reaction and mydriasis in fruits but not in leaves and stems. a) 79... 

Ly. esculentum A. belladonna solanine/hyoscyamine a) Fruits mydriasis and Vitali reaction. Leaves and stem no reaction. b) Mydriasis. c) Alkaloids giving Vitali reaction. a) b) c) Alkaloids present. 79 72 80... 

Ly. esculentum D. stramonium solanine/hyoscyamine a) Strong mydriasis Vitali reaction 1-hyo-scyamine isolated as aurichloride. a) 76... 

The most frequently used color reactions are those developed by Vital and Gerrard and may be briefly described as follows The Vitali Reaction (1). A minute quantity (as little as 0.0001 mg. is sufficient) of solid atropine, Z-hyoscyamine or Z-scopolamine, on a watch glass, is treated with a drop of fuming nitric acid and the liquid evaporated to dryness at 100°. The residue when treated with a drop of freshly prepared solution of ethanolic potassium hydroxide develops a bright purple coloration which slowly fades to a dark red and finally to a colorless liquid. The color sequence can be reproduced by the addition of more potassium hydroxide reagent. 

Phenylglycollyltropeine Mandelyltropeine, homatropine), CigHjiOjN. This is largely used as a substitute for atropine. It crystallises in prisms, m.p. 95-5-98-5°. The hydrobromide, the salt usually employed in medicine, is a crystalline powder, m.p. 217-8° (dec.) the hydrochloride, m.p. 224-5°, and the salicylate are also used. All tl ee are freely soluble in water. The methobromide has m.p. 192-6°. The aurichloride, B. HAUCI4, forms prisms and is sparingly soluble in water. Homatropine, unlike atropine, does not give the Vitali colour reaction (p. 70). Its mydriatic effect is more rapid and transient than that of atropine. 

Color reactions are more or less clearly defined reactions of the substances with suitable reagents. Substance-specific reactions are not usually available, e. g. many compounds with aromatic skeletons give both a positive Vitali-Morin reaction [1 -4] and a positive Marquis reaction [4]. Again, numerous aldehydes react with electron-rich compounds in acidic medium to yield colored substances (cf. Chapters 2 and 3.1). 

W. Ipatieff and W. Nikolaieff observed the formation of phosphine when white phosphorus is heated with hydrogen in a sealed tube at 360° and when water-gas at 400 atm. press, acts on lead phosphate. J. Brossler said that if white phosphorus be added to a mixture of zinc and dil. sulphuric acid, in a short time, spontaneously inflammable phosphine will be produced and if a cone. soln. of alkali hydroxide and zinc be mixed with yellow phosphorus, the spontaneously inflammable gas will be given off at about 60° if the temp, be below 20°, the gas evolved is not spontaneously inflammable. H. Davy, and L. Dusart showed that the gas obtained by the action of zinc and dil. acids on yellow phosphorus contains phosphine, although J. B. A. Dumas questioned the fact. D. Vitali observed that the presence of mercuric chloride retards the formation of phosphine. J. Brossler obtained phosphine by the action of hydrochloric acid and a few drops of nitric acid on tin in the presence of yellow phosphorus. The formation of phosphine during the action of ammonia, and of water on yellow phosphorus has been indicated in connection with the chemical reactions of phosphorus. 

H. Rose obtained a product approximating to a hemitrihydrate by the action of phosphine on an aq. or alcoholic soln. of mercuric chloride. A. Partheil and A. van Haaren worked with an alcoholic soln. and said that the phosphine should be diluted with an inert gas. D. Vitali obtained a similar substance. The yellow product is decomposed by heat by boiling water cone, alkali-lye hydrogen sulphide and by dil. nitric acid. For analogous reactions with mercuric bromide and iodide, vide infra. 

These alkaloids are extracted from animal tissues with the universal buffer solution or with acid solution at pH 4 to 5 (using oxalic or tartaric acid). The alkaloids are then identified micro crystallographically by reaction with Rieneck s salt and by Vitali s reaction (57). 

Morin (74) suggested the use of Vitali s reaction for the determinations of small amounts of atropine. 

A newer approach to the Vitali type of reaction has been reported by Freeman (78) ... 

Empirical Research. In the following paragraphs, our own results of empirical research are presented. With the help of a questionnaire, Vitali Heints [13] carried out new studies in German high schools where redox reactions have been introduced as electron transfer. Several problems are based on preconcepts regarding combustion which have already been mentioned in Chap. 3. However, in Problem 1 of the questionnaire, information about the combustion of copper is asked while, in Problem 2, it is compared to the reaction of copper with chlorine. 

Zerbe, K., O. Pylypenko, F. Vitali, W. Zhang, S. Rouset, M. Heck et al. (2002). Crystal structure of OxyB, a cytochrome P450 implicated in an oxidative phenol coupling reaction during vancomycin biosynthesis. J. Biol. Chem. 211, 47476- 7485. 

The same color display is observed in the case of the modified Vitali test. The alkaloid is ground with sodium nitrate and moistened with sulfuric acid, and subsequently treated with potassium hydroxide reagent. This color reaction has been applied to sixty alkaloids and only veratrine Z-Scopolamine will be used throughout this chapter in preference to Z-hyoscine so as to avoid any possibility of confusion of this alkaloid with Z-hyoscyamine. 

Detection, analysis A. precipitation reagents that effect formation of poorly water soluble salts are, e.g., Dragendorff s, FrOhde s, and Mayer s reagents, picric acid, picrolonic acid, dipicrylamine, phosphomolyb-dic acid, Reinecke s salt, and sodium tetraphenylbo-rate. Special color reactions are used for some groups of A., e.g., Vitali s reaction to detect tropane A., the thalleioquine reaction for Cinchona A., the murexide reaction for purines. 

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