Trichloroacetic acid

• Trichlorethansäure
• TCA

Colorless, slightly acidic smelling crystals

Fixed

1.61 g · cm -3 ( 64 ° C)

59 ° C.

196 ° C.

0.1 hPa ( 20 ° C)

0.65

Very good in water ( 1300 g · l-1 at 20 ° C ), ethanol and diethyl ether

1.4603 (61 ° C)

Risk

• 270 mg · kg -1 ( LD50, mouse, s.c )
• 500 mg · kg -1 ( LD50, mouse, ip)

-503.3 KJ / mol

Template: Infobox chemical / molecular formula search available

The trichloroacetic acid ( TCA briefly, by the British trichloroacetic acid) is a chlorinated organic chemical compound from the group of carboxylic acids. In it, the three hydrogen atoms of the methyl group are completely replaced by chlorine atoms ( substituent). Its salts are called trichloroacetates.

Properties

Trichloroacetic acid, CCl3COOH, is having a pKa value of 0.512 due to the -I effect, a much stronger acid than acetic acid ( pKa 4.75). It forms colorless, pungent-smelling crystals with a melting point of 54 ° C and a boiling point of 196 ° C. In addition, trichloroacetic acid is highly hygroscopic.

Use

Trichloroacetic acid is used in cosmetics for removing cornea ( " peeling" ). Its sodium salt, sodium trichloroacetate was used as a herbicide. In Germany, Austria and Switzerland is not approved as a pesticide more.

In addition, it is used as a precipitating agent for proteins from a cell homogenate or from the culture medium ( at extracellular proteins).

In analytical chemistry readily soluble metals from complex biological samples such as foods or body fluids can be extracted easily with trichloroacetic acid, so that it does not require complicated wet chemical oxidation of the interfering organic matrix. For example, if the calcium content of milk and the iron content in blood can be determined, the aqueous sample is mixed with a TCA solution in a 1:1 ratio and centrifuged after a short extraction time. In the sediment are insoluble components such as denatured proteins and cell fragments. The supernatant can be measured directly.