Mayer reagent

Mayer reagent- Dissolve 1 36 g HgCl2 in 60 mL water and 5 g KI in 10 mL water. Combine both solutions and make up with water to 100 mL. Add a few drops to an acidified solution (HCl or diluted H2SO4) containing the alkaloids, and if alkaloids are present, a white to yellowish precipitate will appear. Special care should be taken since the precipitate may be redissolved by AcOH or EtOH in the solution or excess of reagent. 

Mayer s reagent (gives white precipitate with most alkaloids in a slightly acid solution) dissolve 13.55 g of HgCl2 and 50 g of KI in a liter of water. 

Semmler and Mayer agree that the reagent used and the conditions of temperature, etc., govern the character of the sesquiterpene, or mixture of sesquiterpenes which result. By using sodium methylate very cautiously, they obtained a caryophyllene having the following characters —... 

The remaining aqueous layer was then acidified with acetic acid a saturated aqueous solution of ammonium reineckate was added to a portion, but no precipitation occurred. No precipitate was noted with Valser s or Mayer s reagent. 

E. Ross, J. Kothe, R. Naumann, W. Fischer, W.-D. Mayer, G. Wieland, E. J. Newman, C. M. Wilson, Indicator Reagents , Ullmann s Encyclopedia of Industrial Chemistry, 6th ed., Electronic Release, Wiley-VCH, Weinheim, 2002. 

Mercuric-Potassium Iodide TS Mayer s Reagent) Dissolve 1.358 g of mercuric chloride (HgC ) in 60 mL of water. Dissolve 5 g of potassium iodide (KI) in 10 mL of water. Mix the two solutions, and add water to make 100 mL. 

Stiles ar d Mayer were unable to prepare r-butyllithium by this procedure from sodium-free lithium but found that addition of 1-2% of sodium, added to the melt in prepaiirxg lithium sand, resulted in successful preparation. A similar experience in the preptuation of other lithium reagents has been reported. Curtin and Koehl found that flic copper bronze can also be used to activate lithium. 

Use Medicine (antiseptic), analytical reagents (Nes-sler s reagent, Mayer s reagent). 

Table 1 summarizes the alkaloid producing species found in Malaysia. The plants are listed systematically under family, genus and species. The alkaloids were detected by the Mayer or Dragendorff reagents or by TLC of an alkaloidal extract followed by detection with the Dragendorff reagent. The test results are cited as strong (s), medium (m), weak (w) or just (+) in cases where a positive result was obtained but no attempt was made to estimate the relative amount. The plant parts examined are abbreviated as follows L (leaves), B (bark), S (stem), Wd (wood), Sd (seed), F (fruit), FI (flowers), R (root) and W (whole plant). It is evident from examination of these results as well as from the subsequent chemical studies that have followed that alkaloid rich species predominate in the Families Annonaceae, Apocynaceae and Rubiaceae and to a lesser extent in Lauraceae, Menispermaceae, Verbanaceae, Euphorbiaceae and Rutaceae. 

Note Estimation of the alkaloid is done by Mayer s reagent and it corresponds to 0.038 gm of napelline to Ic.c of the reagent. 

Mbhrle and Mayer " ° oxidized the 3-piperidinopropylamine (182) with mercuric acetate-EDTA reagent to obtain the pyrido[l,2-a]pyrimidine (184), Oxidation of the N-monomethyl and (V,iV-dimethyl derivatives of 182 resulted in the (V-methyl and A,A-dimethypiperidone derivatives of 185. If the reactions were carried out without the addition of EDTA, the perhydropyrido[l,2-o]pyrimidine(183) and its A-methyl derivative also could be isolated from the reaction mixture. " The pyrido[l,2-a]pyrimidine (184) was also prepared from the piperidone (186). " The oxidative cyclization was successfully when applied to the piperidinopropionamides (187) to prepare the pyrido [1,2-a]pyrimidines (188) in addition to 2-oxopiperidino-propionamides. " ... 

In the CSIRO survey of Papua-New Guinea plants, a somewhat more elaborate testing method [19] was adopted finely ground plant material was extracted with ammoniacal chloroform, then the filtered extract was shaken with sufficient dilute acid to neutralise the ammonia and to extract any alkaloid present. The clarified acid solution was tested with Mayer s reagent, and the result rated as - or + to ++++ as in the case of Webb s surveys. The necessary equipment was designed to fit into a portable kit that could be taken into the field. The same procedure was used in some later screens of mainland Australian plants by the CSIRO [20] and in the surveys of orchidaceous plants [24, 25] also in the Tasmanian survey, with some modifications to make it more convenient under field conditions [22]. 

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