Trichloroacetic Acid

What is Trichloroacetic Acid?

Trichloroacetic acid is an organic compound in which three hydrogen atoms of the methyl group of acetic acid get replaced by chlorine atoms. It is a white crystalline solid. It is also known as TCA, TCAA or trichloro ethanoic acid. But its systematic IUPAC name is trichloroacetic acid. As the name suggests, it's an analogue of acetic acid. It is a strong acid which is widely used in clinical chemical and biochemistry. Specially its salts and esters are very famous for their usage in cosmetics. Its salts and esters are called trichloroacetates. 

In 1839, French Chemist Jean – Baptiste Dumas discovered trichloroacetic acid. It is also called aceto - caustin. Its discovery gave a noticeable example to the theory of organic radicals and valances. This theory was based on the facts which were contrary to the beliefs of Swedish Chemist Jons Jakob Berzelius. Thus, Jean – Baptiste Dumas was the first chemist who criticized or questioned the results of the electro – chemical research of Jons Jakob Berzelius. Before the discoveries made by Dumas, results of electro – chemical research by Jons Jakob Berzelius were widely accepted at that time. It started a long debate between Jons Jakob Berzelius and Jean – Baptiste Dumas. 

Formula of Trichloroacetic Acid 

Structure of Trichloroacetic Acid 

It is an organic covalent compound which is formed by the displacement of hydrogen atoms of acetic acid by chlorine atoms. The carbon atom which is bonded with O, OH and CCl3 group is sp2 hybridized and the carbon atom which is bonded to three chlorine atoms and COOH group is sp3 hybridized. 

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Trichloroacetic acid (CCl3COOH)

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3D – Structure of trichloroacetic acid

Properties of Trichloroacetic Acid 

Physical and chemical properties of trichloroacetic acid - Properties of trichloroacetic acid are listed below –

• Its molar mass is 163.38 g/mol. 

• It is a white or colorless crystalline solid. 

• It has a sharp pungent smell. 

• Its density is 1.63 g.cm-3.

• Its melting point is 58 ℃.

• Its boiling point is 197 ℃.

• It is soluble in water. 

• It is acidic in nature. Its pH is 1.2. 

• It turns blue litmus paper into red. 

• Its pKa value is 0.66. 

• It is a stable compound with a flash point over 93 ℃. 

• It is not reactive with water. 

• It is corrosive in nature like other strong acids. 

• Its dipole moment is 3.23 D.

• It reacts with protein. 

Preparation of Trichloroacetic Acid 

It is produced by the reaction of chlorine gas on acetic acid in presence of a catalyst. Reaction is given below –

CH3COOH + 3Cl2 🡪 CCl3COOH + 3HCl 

It can also be produced by the reaction of trichloroacetaldehyde with oxygen or by the oxidation of trichloroacetaldehyde. 

Uses of Trichloroacetic Acid 

Due to its stable and strong acidic nature, trichloroacetic acid is used in many fields to fulfill various purposes. Its few applications are listed below –

• It is widely used in clinical chemistry in the preparation of formulations. 

• In biochemistry, it is used for precipitation of macromolecules. For example, it can precipitate proteins, DNA and RNA. 

• It is used in the chemical peels and tattoo removal.

• It is used in cosmetics. 

• It is used on the skin for chemoablation of warts. 

• In diluted form it can be used on the genital warts as well. 

• It can be used even during pregnancy for skin infections. 

• Its sodium salt was used as an herbicide till the 1980s. 

Effects of Trichloroacetic Acid on Health And Environment 

Trichloroacetic acid is a strong acid. So, it is a corrosive compound. Its overuse on skin can cause skin damage. Its short exposure can cause serious temporary or long - lasting injuries. It can be lethal for rats when taken 5000 mg/kg. It is harmful for the environment as well. 

Trichloroacetic Acid: Summary in Tabular Form