2-hydroxy-1,4-naphthoquinone

Structural formula
General
Surname	2-hydroxy-1,4-naphthoquinone
other names	2-hydroxy- p- naphthoquinone 2-hydroxy-1,4-naphthalenedione Lawson CI 75480
Molecular formula	C 10 H 6 O 3
Brief description	yellow odorless solid
External identifiers / databases
CAS number 83-72-7 EC number 201-496-3 ECHA InfoCard 100.001.361 PubChem 6755 ChemSpider 10430995 DrugBank DB04744 Wikidata Q1075492
properties
Molar mass	174.16 g mol −1
Physical state	firmly
solubility	heavy in water (2 g l −1 at 20 ° C) sparingly soluble in ethanol and acetone soluble in DMSO practically insoluble in ether and benzene
safety instructions
GHS labeling of hazardous substances Caution H and P phrases H: 315-319-335 P: 261-305 + 351 + 338
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

2-Hydroxy-1,4-naphthoquinone is a chemical compound from the group of ketones and naphthols . It is isomeric to juglone , the color of the walnut tree .

Occurrence

Young branches of the henna ( Lawsonia inermis ).

2-Hydroxy-1,4-naphthoquinone occurs naturally in a concentration of one to two percent in the leaves of the henna bush , but also in other Lawsonia and Impatiens species.

Extraction and presentation

2-Hydroxy-1,4-naphthoquinone can be obtained by reacting ninhydrin with thionyl chloride , diazomethane and subsequent alkaline saponification .

properties

2-Hydroxy-1,4-naphthoquinone is a yellow, odorless, crystalline, flammable solid that is sparingly soluble in water. It decomposes when heated above 195–196 ° C.

use

2-Hydroxy-1,4-naphthoquinone is used as a dye (since it is the main ingredient in henna).

safety instructions

The mutagenicity tests carried out with the compound had negative, but in some cases also positive results. After a critical examination and taking into account more recent test results, the Federal Institute for Risk Assessment came to the conclusion in 2003 that there is no risk of a mutagenic effect for humans. In a more recent evaluation by the Scientific Committee on Consumer Safety of the European Commission, a maximum amount of 1.4% Lawson in henna hair dyes is considered safe. For allergic skin reactions that show up shortly after henna tattoos have been applied, it is likely that they are mostly caused by p-phenylenediamine , which has been added to deepen the color ("black henna"). Some tests suggest a non-negligible toxic potential with repeated oral exposure.

Individual evidence

1. ↑ ^{a b c d e f} Entry on 2-hydroxy-1,4-naphthoquinone in the GESTIS substance database of the IFA , accessed on July 23, 2016(JavaScript required) .
2. ^ ^{A b} Lawrence H. Keith, Douglas B. Walters: National Toxicology Program's Chemical Solubility Compendium . CRC Press, 1991, ISBN 978-0-87371-653-6 , pp. 238 ( limited preview in Google Book search).
3. ↑ Lawrence H. Keith, Douglas B. Walters: The National Toxicology Program's Chemical Data Compendium . CRC Press, 1991, ISBN 978-0-87371-716-8 , pp. 893 ( limited preview in Google Book search).
4. ^ S. Huneck, Joachim Thiem: RÖMPP Lexikon Naturstoffe, 1st edition, 1997 . Georg Thieme Verlag, 2014, ISBN 3-13-179541-7 , p. 1886 ( limited preview in Google Book search).
5. ^ Stefan Berger, Dieter Sicker: Classics in Spectroscopy . John Wiley & Sons, 2009, ISBN 3-527-32516-6 , pp. 196 ( limited preview in Google Book search).
6. ^ HS Freeman, AT Peters: Colorants for Non-Textile Applications . Elsevier, 2000, ISBN 978-0-08-052938-7 , pp. 438 ( limited preview in Google Book search).
7. ^ Opinion Of The Scientific Committee On Cosmetic Products And Non-Food Products Intended For Consumers Concerning Lawsone Colipa N ° C146 , September 17, 2002
8. ^ Health assessment of the substance "Lawson": BfR opinion of 10 January 2003
9. ↑ Opinion on Lawsonia inermis (Henna) COLIPA n ° C169: Statement of the SCCS dated September 19, 2013