2,6-dichloroquinone-4-chloroimide

Structural formula
General
Surname	2,6-dichloroquinone-4-chloroimide
other names	Gibbs reagent; N , 2,6-trichloro-p-benzoquinonimide;
Molecular formula	C 6 H 2 Cl 3 NO
Brief description	dark yellow, crystalline solid
External identifiers / databases
EC number	202-937-2
ECHA InfoCard	100.002.671
PubChem	7556
Wikidata	Q209277
properties
Molar mass	210.45 g mol −1
Physical state	firmly
Melting point	65-67 ° C
solubility	practically insoluble in water (20 ° C)
safety instructions
H and P phrases	H: 242-315-319
	P: 210-302 + 352-305 + 351 + 338
Toxicological data	> 500 mg kg −1 ( LD 50 , rat , oral )
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

2,6-dichloroquinone-4-chlorimide, or Gibbs' reagent , is an N - halogenated quinoneimine derivative that is used in analytical chemistry as a detection reagent for phenols . Its reaction product with phenol , the Tillmans reagent , is used as a redox indicator . Its use as a detection reagent was first described by Harry Drake Gibbs in 1927 .

Presentation and extraction

A synthesis of 2,6-dichloroquinone-4-chlorimide starts from 4-nitrophenol , which is converted into 2,6-dichloro-4-nitrophenol in the first step by means of chlorination . A reduction with tin then gives the 2,6-dichloro-4-aminophenol. In the last step, this is oxidized to the target compound with potassium hypochlorite .

properties

2,6-dichloroquinone-4-chloroimide forms yellow needles that melt at 67–68 ° C. Thermal decomposition is observed above 170 ° C. The compound is very difficult to dissolve in water. The solubility is somewhat better in alcohols and very good in acetone and ethers.

Solubilities at 20 ° C
solvent	water	Methanol	Ethanol	n-propanol	n-butanol	acetone
Solubility in g / 100 ml	0.003	10	5	2.5	2.5	100
solvent	Dioxane	Diethyl ether	chloroform	benzene	n-heptane
Solubility in g / 100 ml	33	30th	50	35	1.5

The compound is explosive in terms of the Explosives Act and is assigned to substance group C there.

use

2,6-dichloroquinone-4-chlorimide is used in organic analytical chemistry as a detection reagent for phenols which are unsubstituted in the para position. The reaction of the reagent with phenols is favored compared to the ortho position in the para position. The substance can also be used as a spray reagent.

Individual evidence

↑ ^a ^b ^c data sheet 2,6-dichloroquinone-4-chloroimide from Sigma-Aldrich , accessed on May 14, 2017 ( PDF ).
↑ ^a ^b ^c Entry on 2,6-dichloro-4- (chlorimino) cyclohexa-2,5-dienone in the GESTIS substance database of the IFA , accessed on January 10, 2017(JavaScript required) .
↑ HD Gibbs: Phenol tests: III. The indophenols test. In: J. Biol. Chem. 72, 1927, pp. 649-664.
↑ ^a ^b ^c A. Kollrepp: About derivatives of chlorinated para-nitrophenols. In: Liebigs Ann. Chem. 234, 1886, pp. 1-34, doi: 10.1002 / jlac.18862340102 .
↑ ^a ^b ^c D. Svobodová, P. Křenek, M. Fraenkl, J. Gasparič: Color Reaction of Phenols with the Gibbs Reagent. The Reaction Mechanism and Decomposition and Stabilization of the Reagent. In: Microchim. Acta . I, 1977, pp. 251-264, doi: 10.1007 / BF01213035 .
↑ Announcement of the new findings made by BAM since 1987 in accordance with § 2 SprengG - notification of assessment no. 370 of October 1, 1997 pdf link .

[Sigma-1] ta sheet 2,6-dichloroquinone-4-chloroimide from Sigma-Aldrich , accessed on May 14, 2017 ( PDF ).

[GESTIS-2] Entry on 2,6-dichloro-4- (chlorimino) cyclohexa-2,5-dienone in the GESTIS substance database of the IFA , accessed on January 10, 2017(JavaScript required) .

[3] HD Gibbs: Phenol tests: III. The indophenols test. In: J. Biol. Chem. 72, 1927, pp. 649-664.

[Kollrepp-4] A. Kollrepp: About derivatives of chlorinated para-nitrophenols. In: Liebigs Ann. Chem. 234, 1886, pp. 1-34, doi: 10.1002 / jlac.18862340102 .

[Krenek-5] D. Svobodová, P. Křenek, M. Fraenkl, J. Gasparič: Color Reaction of Phenols with the Gibbs Reagent. The Reaction Mechanism and Decomposition and Stabilization of the Reagent. In: Microchim. Acta . I, 1977, pp. 251-264, doi: 10.1007 / BF01213035 .

[6] Announcement of the new findings made by BAM since 1987 in accordance with § 2 SprengG - notification of assessment no. 370 of October 1, 1997 pdf link .