Vanillin-phosphoric acid

Classical examples of this type of reaction are the various dimethylaminobenz-aldehyde reagents (q.v.) and vanillin-acid reagents, of which one, the vanillin-phosphoric acid reagent, is already included in Volume 1 a. The aldol condensation of estrogens is an example for the reaction mechanism (cf. Chapter 2, Table 6). According to Maiowan indole derivatives react in a similar manner [1]. Longo has postulated that catechins yield intensely colored triphenylmethane dyes [2]. 

Test for phytosterols after derivatization with vanillin-phosphoric acid reagent (shots taken in white light) ... 

A Natural products-polyethylene glycol reagent (NP/REG No. 28) —> UV-355nni B Vanillin-phosphoric acid (VP reagent No. 41) —> vis... 

B Vanillin-phosphoric acid reagent (VPA No. 41) —i vis C Antimony-(III)-chloride reagent (SbCljNo. 4) —> UV-365 nm... 

Thin-layer chromatography (TLC) is a good method for detecting the presence of cucurbitacins in a plant extract. The best results to date have been achieved using high-performance TLC (HPTLC) plates [41] with silica gel and chloroform-methanol (95 10) (Table 1) or toluene-ethyl acetate (25 75) as mobile phases [3,11]. Reversed-phase (RP) HPTLC plates with methanol-water (7 3) have also been used to separate cucurbitacins [3]. The compounds are easily detected with vanillin-sulphuric acid or vanillin-phosphoric acid reagents and ultraviolet light (UV) at 365 nm [11]. 

Vanillin-sulfuric acid Vanillin-phosphoric acid... 

Fig. 3a The TLC of the ethanol extracts of Radix Trichosanthis sprayed with Vanillin-Phosphoric acid reagent (VIS)...

Vanillin-Phosphoric Acid and Vanillin-Potassium Hydroxide... 

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