Malachite green

Overview

Basic Green 4 is an organic compound that is also referred to as Malachite Green. It is commonly used in dyes and as an antibacterial . In particular, Basic Green 4 can be categorized under reactive groups such as Pyridines, Phosphines, and Amines; Aromatic, Hydrocarbons; Aliphatic Unsaturated, Hydrocarbons; Conjugated Dienes; Phosphonium Salts and Quaternary Ammonium . The name of the compound is obtained from its resemblance with the color of the mineral malachite. In addition, Basic Green 4 can be seen as dark green crystals characteristic of a distinct metallic luster as well as a blue-green solution when dissolved in water. Basic Green 4 goes by the molecular formula C23H25CIN2 and has a high solubility in ethanol, amyl alcohol, methanol, and water (Cameo Chemicals) . In particular, 1 part of the compound is soluble in 15 parts of water (4.0 x 10 + 4mg/l at 250 C), whereas one part of the compound is also soluble in 15 parts of alcohol . When the compound is heated, its decomposition results in hydrogen chloride and nitrogen oxide, highly toxic fumes. In addition, it is estimated that its vapor pressure is 2.4 x 10 – 13MM Hg at 250 C.

Preparation

To prepare Basic Green 4, 14 grams of benzaldehyde and 35 grams of dimethylaniline are combined with 31.5 grams of concentrated hydrochloric acid and the contents are heated to 1000 C for a period of 24 hours with the aid of a reflux condenser. The alkalinity of the resulting solution is enhanced by sodium hydroxide, then the reacting mass is distilled over steam to get rid of traces of dimethylaniline and benzaldehyde. The addition of 1 liter of water to the leuco base allows for the separation of hard granules. The granules are then filtered and the compound is unbound from alkali .
Notably, the oxidation of the leuco base starts by melting 10g of the base over heat and adding a mixture of 4g of acetic acid and 27g of hydrochloric acid and about 3000ml of water. Nonetheless, 7.5g of a fine paste comprising refined lead oxide is gradually mixed in while stirring should continue for about 2 hours after the initial addition. Moreover, the unreacted lead oxide is obtained through filtration and the resulting filtrate is exposed to heat until it attains its boiling point, after which sodium sulfate is incorporated to separate excess lead. The resulting solution is then placed under heat to bring it to boil for effective precipitation with sodium hydroxide. Upon cooling, it is then filtered, washed, dehydrated, and further broken down in light petroleum, then impurities are filtered off, the resulting solution is evaporated to remove petrol, which yields pure Basic Green 4.

Uses

Basic Green 4 is used in Local, Anti-Infective Agents; Industrial, Fungicides. As an internal antiseptic, it is administered to treat canine dysentery ad calf scours, whereas as an external antiseptic it can be applied to abrasions and infected wounds as a triple dye that consists of gentian violet, brilliant green, and rivanol . Malachite green oxalate (arylmethane dye) is also used as a remedy for mycotic infections in aquaculture. Traditionally, malachite green is used as a dye .

Toxicity

Ingestion, inhalation or skin contact with Basic Green 4 can result in critical injuries and in some cases death. In particular, when one come in contact with the molten form of the substance they may experience acute burns on their eyes and skin. It is worth noting that the effects may be delayed upon inhalation or even contact. Moreover, exposure of the element to fire may result in the production of toxic, corrosive and irritating gases. Furthermore, runoff drawn from dilution with water or fire control may also be highly toxic or corrosive in a way that results in pollution .

Risk Management

Evacuation and Isolation are the most instant precautionary measures for either spills or fire. In particular, for solid spills, isolation should be restricted to 25metres whereas for liquid leaks or spills isolation should be restricted to 50metres. In case a tank is involved in a fire accident then isolation should be restricted to 800metres . To fight small fires, use CO2, dry chemical, alcohol-proof foam or a water spray. For massive fires, caution should be taken and the fire should be fought from a distance with monitor nozzles or unmanned hoses to ensure that water does not get into the tanks . Breathing apparatus and protective clothing should always be worn during firefighting. For first aid upon contact, one should flush water on their eyes or skin for about 20 minutes before contacting medical personnel.

References

1. Barrowcliff, Marmaduke. Organic Medicinal Chemicals (Synthetic and Natural). Chizine Publications, 2018. 
2. Cameo Chemicals. C.I Basic Green 4. National Oceanic and Atmospheric Administration, 2018. Web. 
3. PubChem. Basic Green 4. National Center for Biotechnology Information, 2018. Web. Rossoff, Irving .S. Handbook of Veterinary Drugs. Springer Publishing Company, 1974.

Chemical Properties

dark green crystals with a metallic luster

Uses

Biological stain, dye reagent, acid base indicator: pH 0.0 yellow, 2.0 green;11.6 green, 14 colorlessMalachite Green oxalate is used as the staining solution for embedded botanical material and as a spore stain. It is also used in studying the photocatalytic degradation with TiO2/WO3. It is employed for determining phosphate in serum and as a reference material in analytical chemistry for the quantification. It is also used as a pH indicator between pH 0.2 - 1.8. It is used as a dye for materials such as silk, leather, and paper.

Uses

Malachite Green oxalate salt has been used:

• in the preparation of Alexander staining solution for cell viability test
• in malachite green-ammonium molybdate assay for determining the adenosine triphosphatase (ATPase) activity of binding immunoglobulin protein (BiP)
• as a hydrophobic ion, to study the label-free molecular transport in the living cell membranes of Escherichia coli in real time by second-harmonic generation (SHG) method

Definition

A salt or ester of oxalicacid.

General Description

Malachite Green is used for bacterial spore staining by Schaeffer and Fulton`s method. It can also be used in place of methyl green in the Pappenheim stain, when combined with the Gram stain.

Biochem/physiol Actions

Malachite green is used in the treatment of fungal and parasitic infections in fish.