Ethyl green

Structural formula
General
Surname	Ethyl green
other names	CI 42590 Methyl green (mistakenly) 4 - {[4- (Dimethylamino) phenyl] [4- (dimethyliminio) cyclohexa-2,5-dien-1-ylidene] methyl} - N -ethyl- N , N -dimethylanilinium bromide chloride (zinc chloride)
Molecular formula	C 27 H 35 BrClN 3 • ZnCl 2
Brief description	dark red-brown, crystalline solid
External identifiers / databases
CAS number 7114-03-6 EC number 230-415-4 ECHA InfoCard 100,027,651 PubChem 3084002 ChemSpider 2341130 Wikidata Q906536
properties
Molar mass	653.26 g mol −1
Physical state	firmly
Melting point	207 ° C
solubility	soluble in water (70 g l −1 at 20 ° C) heavy in ethanol (1 g l −1 ) insoluble in xylene
safety instructions
GHS labeling of hazardous substances danger H and P phrases H: 314-351-411 P: 273-280-301 + 330 + 331-305 + 351 + 338-308 + 310
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Ethyl green is a green triphenylmethane dye . Ethyl green is also often referred to and sold as methyl green.

Methyl green and terminology

Ethyl green ( CI 42590) is often referred to as methyl green (CI 42585, CAS No. 82-94-0), although the latter has probably not been manufactured for years. At Merck Index and Sigma-Aldrich , the related methyl green is listed as ethyl green.

Instead of an ethyl group, methyl green has a methyl group on the nitrogen atom; this methyl group can easily dissociate to form crystal violet . Physically, the two dyes hardly differ, so the use of methyl green has no effects.

Methyl green, which can hardly be distinguished from ethyl green

synthesis

Ethyl green is produced by ethylation of crystal violet with ethyl bromide and subsequent salting out in sodium chloride . Therefore, ethyl green is mostly in the form of a mixed bromide-chloride. But it is unlikely that the stoichiometry of Cl ^- to Br ^{- is} exactly 1: 1. Usually ethyl green is sold as zinc salt .

properties

Ethyl green forms a green powder that is soluble in water. It is very similar to the dye crystal violet. Ethyl green is somewhat more stable than methyl green because its methyl group can easily dissociate.

In the pH range from 0.8 to 1.8, the transition point of ethyl green from yellow to blue is.

use

Ethyl green is widely used as a dye. It is used, for example, in microscopy as a nuclear and mitochondrial pigment. Because of its bluish-green color, ethyl green is also used as a counter- dye for staining in histology , for immunostaining and in-situ hybridization .

Ethyl green also serves to differentiate colors between diphtheria and other bacteria . In connection with pyronine G it is also used to differentiate between DNA and RNA (Unna-Pappenheim staining). For this purpose, the dye mixture must not contain any crystal violet, which can, however, be isolated from the methyl green by shaking with chloroform.

Pyronine G.

Chance of ethyl green was also used to live coloration of ciliates used. In addition, it is used in the confocal microscope to be able to detect double-stranded DNA in skin cells.

Finally, ethyl green was also used in forensics.

literature

• RW Horobin, JA Kiernan: Conn's Biological Stains: A Handbook of Dyes, Stains and Fluorochromes for Use in Biology and Medicine. 10th edition. BIOS Scientific Publ., 2002, ISBN 1-85996-099-5 , pp. 196 and 197.

Web links

• Overview of ethyl green (in English)

Individual evidence

1. ↑ ^{a b c} Data sheet methyl green zinc chloride double salt (CI 42590) (PDF) from Merck , accessed on March 31, 2011.
2. ↑ Entry on methyl green. In: Römpp Online . Georg Thieme Verlag, accessed on June 1, 2014.
3. ↑ ^{a b c} Entry on methyl green, zinc chloride salt in the GESTIS substance database of the IFA , accessed on January 8, 2020(JavaScript required) .
4. ↑ Other names for methyl green:
   • CI Basic Blue 20
   • Paris green
   • Heptamethyl- p -rosaniline chloride
   • Double green SF
   • Double Green SF
   • Hoffmann's green
   • Green powder
   • Vert Lumière
   • Vert de Paris
   • Vert Etincelle
5. ↑ Floyd J. Green: Sigma-Aldrich Handbook of Stains, Dyes, and Indicators . Aldrich Chemical Company, Milwaukee, Wisconsin 1990, ISBN 0-941633-22-5 , p. 458.
6. ↑ Harald Conn, Ralph D. Lillie (Ed.): Biological Stains. 9th edition. Lippincott Williams and Wilkins, 1977, ISBN 0-683-05034-6 , p. 280.
7. ↑ Marilyn Gamble, John D. Bancroft: Theory and Practice of Histological Techniques. 5th edition. Churchill Livingstone, 2002, ISBN 0-443-06435-0 .
8. ^ G. Clark: Staining procedures used by the Biological Stain Commission. 4th edition. Williams and Wilkins, Baltimore 1981.
9. ↑ PG Unna: Monthly booklets for practical dermatology. Volume 55, 1902, p. 76.
10. ^ W. Foissner: Basic light and scanning electron microscope methods for taxonomic studies of ciliated protozoa. In: Europ J Protistol. 27, 1991, pp. 313-330.
11. ↑ Y. Ito, Y. Otsuki: Localization of apoptotic cells in the human epidermis by an in situ DNA nick end-labeling method using confocal reflectant laser microscopy. In: J Histochem Cytochem. 46 (6), 1998, pp. 783-786. PMID 9603792 ; PDF (free full text access).
12. ↑ JB Kempton, WF Rowe: Contrast Enhancement of Cyanoacrylate-Developed Latent Fingerprints Using Biological Stains and Commercial Fabric Dyes. In: Journal of Forensic Sciences. 37 (1), 1992, pp. 95-105.