2.6- Dibromoquinone-4-chlorimide

C6H2Br2CINO 2,6-dibromoquinone-4-chlorimide 537-45-1 25.00 2.1919 2 6268 C6H3CIF3N 2-chloro-5-(trifluoromethyl)pyridlne 52334-81-3 25.00 1.4475 2... 

Dibromoquinone-4-chlorimide 2,6-Dibromo-4-(chioroimino)- 2,6-cyciohexadien-1-one CsHjBrjCiNO 637-46-1 299.347 ye pr (ai or HOAc) 83 vs EtOH... 

The Gibbs indophenol test is useful for the identification of phenol in phenolic resins and in substances that split off phenol or phenol derivatives on heating. Polycarbonates or epoxy resins as well as some HT-thermoplastics are examples of this. Heat a small sample for a maximum of 1 min in a pyrolysis tube and cover the opening of the tube with a piece of prepared filter paper. To prepare the paper, drench it in a saturated ether solution of 2,6-dibromoquinone-4-chlorimide and then air-dry it. After the pyrolysis, hold the paper over ammonia vapor or moisten it with 1 - 2 drops of dilute ammonia. A blue color indicates phenol (cresol, xylenol). 

Solvent program 100% solvent A for 21 min, change to 100% solvent B. Flow rate 2.0 mL/min. Pyridoxine is reacted with 2.6-dibromoquinone-4-chlorimide. 

Kawamoto and coworkers used HPLC and post-column derivatization with 2,6-dibromoquinone-4-chlorimide to quantify PN in pharmaceutical products (88). The condensation product shows strong absorption in the visible spectrum (650 nm) detection has been reported to be almost seven times more sensitive than UV (250 nm) detection of PN. The main advantage of this method is selectivity other B vitamins or caffeine (often present in vitamin preparations) were shown not to interfere in PN quantiflcation. The disadvantage of the method is that two postcolumn reaction pumps with reaction coils are required to deliver reagents to the column eluate. Furthermore, only PN can be analyzed by this method, while most modem quality control programs tend to optimize vitamin analyses by simultaneous analysis of several vitamin compounds. 

T Kawamoto, E Okada, T Fujita. Post-column derivatization of vitamin B-6 using 2,6-dibromoquinone-4-chlorimide. J Chromatogr 267 413-419, 1983. 

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