What does phosphomolybdic acid stain?
Phosphomolybdic is used as a stain for developing thin-layer chromatography plates, staining phenolics, hydrocarbon waxes, alkaloids, and steroids. Conjugated unsaturated compounds reduce PMA to molybdenum blue. The color intensifies with increasing number of double bonds in the molecule being stained.
What is the principle of TLC?
The principle of TLC is the distribution of a compound between a solid fixed phase (the thin layer) applied to a glass or plastic plate and a liquid mobile phase (eluting solvent) that is moving over the solid phase.
How does potassium permanganate work TLC?
Potassium Permanganate This particular stain is excellent for functional groups which are sensitive to oxidation. Alkenes and alkynes will appear readily on a TLC plate following immersion into the stain and will appear as a bright yellow spot on a bright purple background.
How do you make phosphomolybdic acid stain?
A3.1 GENERAL STAINS Phosphomolybdic Acid (PMA): Dissolve 10 g of phosphomolybdic acid in 100 mL of absolute ethanol. Potassium Permanganate: Dissolve 1.5 g of KMnO4, 10 g of K2CO3, and 1.25 mL of 10% NaOH in 200 mL of water. Vanillin: Dissolve 15 g of vanillin in 250 mL of ethanol and add 2.5 mL of conc. sulfuric acid.
What functional groups does phosphomolybdic acid react with?
Visualization Summary
| UV Light: For aromatics + conjugated systems | Iodine: Visualizes ~half the time. Strongly reacts with aromatics |
|---|---|
| Permanganate: For alkenes, alkynes, or oxidizable groups (aldehydes, alcohols) | Phosphomolybdic Acid (PMA): For alcohols, phenols, alkenes, and many carbonyl compounds |
How do you make Anisaldehyde stain?
p-Anisaldehyde General purpose stain, particularly good with groups with nucleophilic properties. Add 15 ml of AcOH and 3.5 mL of p- Anisaldehyde to 350 mL ice cold EtOH. Cautiously add 50 mL concentrated H2SO4 dropwise over 60 minutes. Store unused portion at 0°C.
What is an Rf value in TLC?
In thin-layer chromatography, the retention factor (Rf) is used to compare and help identify compounds. The Rf value of a compound is equal to the distance traveled by the compound divided by the distance traveled by the solvent front (both measured from the origin).
How do TLC stains work?
When a developed TLC plate is placed in the chamber and capped, the iodine sublimes and reacts with the compounds on the plate, forming yellow-brown spots (Figure 2.33d). This stain will work with approximately half the compounds you may encounter.
Why iodine is used in TLC?
Iodine Staining. The iodine staining technique allows us to carry around a marked version of our TLC run rather than having to pencil sketch our spots in the UV viewer. Some compounds might not even appear under UV light, making other visualization techniques such as iodine staining necessary.
What does Anisaldehyde stain?
The p-anisaldehyde and vanillin stains are general purpose, and work for many strong and weak nucleophiles (alcohols, amines), and for many aldehydes and ketones. They do not work on alkenes, aromatics, esters, or carboxylic acids.
What are the chemicals in an Anisaldehyde TLC stain?
TLC Stains
| p-Anisaldehyde (CAS:123-11-5) | 4mL |
|---|---|
| Sulfuric Acid | 5mL |
| Acetic Acid | 2mL |
| Ethanol | 150mL |
What kind of stain to use with phosphomolybdic acid?
% phosphomolybdic acid in ethanol. More PMA can be used however as stains go PMA is relatively expensive. TLCs developed with PMA stain upon heating give green/dark green/dark blue spots on a yellow/green background (see picture).
How is phosphomolybdic acid used in histology?
It is used as a stain in histology and in organic synthesis. Phosphomolybdic acid is a component of Masson’s trichrome stain. Phosphomolybdic is used as a stain for developing thin-layer chromatography plates, staining phenolics, hydrocarbon waxes, alkaloids, and steroids.
What kind of stain is dodeca molybdophosphoric acid?
It is also known as dodeca molybdophosphoric acid or PMA, is a yellow-green chemical compound that is freely soluble in water and polar organic solvents such as ethanol. It is used as a stain in histology and in organic synthesis. Phosphomolybdic acid is a component of Masson’s trichrome stain.
What is the standard state of phosphomolybdic acid?
Phosphomolybdic acid. Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Phosphomolybdic acid, also known as dodeca molybdophosphoric acid or PMA, is a yellow-green chemical compound that freely soluble in water and polar organic solvents such as ethanol.