Indole

Colorless leaflets, purely a flower-like and contaminated possess an unpleasant odor

Fixed

1.22 g · cm -3 ( 20 ° C)

52 ° C.

254 ° C.

1.6 Pa (25 ° C)

In water 3.6 g · l-1 (25 ° C)

Risk

1000 mg · kg -1 ( LD50, rat, oral)

Template: Infobox chemical / molecular formula search available

Indole is a chemical substance, or more precisely an aromatic heterocycle and comes as a structural fragment in many natural products before.

History

The indole chemistry began with the study of the dye frequently used indigo. Indigo can be further converted into isatin and oxindole. 1866 Adolf von Baeyer reduced oxindole using zinc dust to indole. In 1869 he proposed a structural formula for indole.

Certain indole derivatives were important dyestuffs until the end of the 19th century. In the 1930s, interest in indole increased when it became known that indole basic constituent of many important natural products such as alkaloids (for example, strychnine and auxin ) and the amino acid tryptophan and of their derived neurotransmitters (serotonin, melatonin ) is. It remains an active area of ​​research today.

Occurrence

Indole is jasmine oil, gold paint oil, but also contained in the flowers of false acacia and Arum. In low concentrations of indole gives the typical floral scent and is therefore also added perfumes. In higher concentrations of indole, as a degradation product of the amino acid tryptophan, in addition to skatole (3- methylindole ), cause of the typical odor of feces. It is also included in the boiling at 240 to 260 ° C coal tar fraction.

Indole is part of the proteinogenic amino acid tryptophan.

Representation

Indole or indole derivatives can be represented in different ways. Among other things, by:

• Fischer's indole synthesis:

• Japp - Klingemann reaction
• Bishler - Möhlau indole synthesis
• Larock indole synthesis
• Madelung indole synthesis
• Leimgruber indole synthesis Batcho
• Nenitzescu indole synthesis
• Gassman Indole Synthesis
• Reissert indole synthesis

Use

Indole building block for dyes, hormones, and alkaloids. The most famous derived from indole dye is indigo, but also the ancient dye purple is such a derivative. The indole - module plugged et al in the hormone melatonin (N- acetyl-5- methoxytryptamine ) in the neurotransmitter serotonin (5- hydroxytryptamine ) and the auxin indole-3 -acetic acid. Among the alkaloids, which contain indole, the Strychnos alkaloids ( strychnine and brucine, for example ), ergot alkaloids ( ergotamine and its synthetic derivative of LSD) and psilocybin mushroom ingredient can be mentioned. It is also used for the production of artificial jasmine and Neroliöle.

Properties

Indole is weakly basic, but forms with acids hardly salts; Instead, it reacts readily resinous polymers. By alkali metals the NH proton is abstracted. In electrophilic reactions reacts preferentially the pyrrole ring. Indole inhibits the enzymes chymotrypsin, lysozyme and tryptophanase.

Proof

Of the indole test is used in the identification of bacteria. To do that, a drop dimethylaminobenzaldehyde ( Ehrlich 's reagent, Kovacs reagent) in the MIO - tube Bunte series, which turns cherry red when tryptophan was degraded to indole.

Indole derivatives

There are numerous indole derivatives, which in nature (for example, tryptophan), art (Example: Indigo ) and Pharmacology (example: Tinazolin hydrochloride) play a role.