4’,5’-Dibromofluorescein

Dibromofluorescein is prepared by treating fluorescein in 80 per cent, acetic acid solution with the theoretical quantity of bromine. 

It may be converted into dibromofluorescein diacetate as follows. Reflux a mixture of 10 g. of dibromofluorescein, 40 ml. of redistilled acetic anhydride and 1 drop of concentrated sulphuric acid for 1 hour, pour into water, filter, wash, and dry the resulting diacetate (95 per cent, yield) has m.p. 210°. Upon recrystallisation from acetic anhydride or nitrobenzene, the pure diacetate (colourless or pale yellow plates), m.p. 211°, is obtained. Hydrolysis with alcoholic sulphuric acid gives a quantitative yield of pure dibromofluorescein, m.p. 285°. 

Treatment of this same 4, 5 -dibromofluorescein intermediate with mercuric acetate and conversion to the disodium salt yields the hydroxymercuric analogue merbromin or mercurochrome [129-16-8] (41). It was once a widely used antiseptic, especially for skin disinfection, and was even adrninistered internally. However, it has been replaced by more effective antibacterial agents. 

Eosin [15086-94-9] (tetrabromofluorescein), C2QHgBi40, made by the bromination of fluorescein, is both a dye and an adsorption indicator. Eosin Y /7 7372-87-17, C2QH Br40 2Na, the disodium salt, is a biological stain. 475 -Dibromofluorescein [596-03-2], C2QH2QBr20, is used in D C Orange No. 

Mercury dibromofluorescein mercurochrome, merobromin, [2 ,7 -dibromo-4 -(hydroxy-mercurio)-fluorescein di-Na salt] [129-16-8] M 804.8, m>300°. The Na salt is dissolved in the minimum vol of H2O, or the free acid suspended in H2O and dilute NaOH added to cause it to dissolve, filter and acidify with dilute HCl. Collect the ppte wash with H2O by centrifugation and dry in vacuum. The di Na salt can be purified by dissolving in the minimum volume of H2O and ppted by adding EtOH, filter, wash with EtOH or Mc2CO and dry in a vacuum. Solubility in 95% EtOH is 2% and in MeOH it is 16%. [J Am Chem Soc 42 2355 7920.]... 

Eosin.—Into a flask containing 16-5 g. (0-05 mole) of fluorescein under 80 c.c. of alcohol, 36 g. (12 c.c.) of bromine are dropped with shaking from a tap funnel during the course of twenty minutes. When half the bromine has been added, and the fluorescein has been converted into dibromofluorescein, all the solid material disappears temporarily, since dibromofluorescein is soluble in alcohol, but later the sparingly soluble eosin begins to crystallise. 

Titration with Pb(CH3C02)2 to give Pb3(P04)2 or PbC204. End point detected with dibromofluorescein (PO -) or fluorescein (C20 ). 

Arakawa et al.82) employed various 9-phenyl xanthene derivatives as the dye for DSC, and found that Eosin Y (EY Dye 18) shows relatively high conversion efficiency of 1.3% under 100 mW-cm"2 irradiance. They clarified the efficiency of 9-phenyl xanthene derivatives as follows EY > Dibromofluorescein > Fluorescein = Fluorescin > Rhodamin B > Dichlorofluorescein > Uranine >... 

DIBROMOETHANE (MAK) see EIY500 DIBROMOFLUORESCEIN see DD0200 4, 5 -DIBROMOFLUORORESCEIN see DD0200... 

Fig. 10-8 shows the observed CIDEP spectra for the reaction of triplet eosin Y (FlBr/ ) with duroquinone. In this figure, CIDEP spectra of the duroquinone radical anion were only observed. The spectra of Xn" were not observed because of its fast spin relaxation. As clearly shown in Fig. 10-8, the initial spectrum measured at 60 ns after the laser excitation showed an emissive polarization, which was due to the usual p-type TM. This polarization was found to change as the delay time was increased. The spectrum measured at 200 ns after the excitation showed a strong absorptive polarization, which was proposed to be due to the d-type TM. Similar polarization changes were also observed for such dyes as erthrosin B (FlLi ) and dibromofluorescein (FlBr2 ) which contain heavy atoms. On the other hand, an emissive polarization was only observed for the reaction of fluoresein (Fl ), which contain no heavy atom. From these results, Tero-Kubota et al. concluded that the strong absorptive... 

MEK, 2-butanone, methyl ethyl ketone MEMO, 2-methoxyethoxymethylchloride Mercurochrome, mercury dibromofluorescein MES, 2-(7V-morpholino)-ethanesulfonic acid MESNA, Na 2-mercaptoethanesulfonate Metal impurities, by complexation by ion exchange resins by precipitation removal by extraction removal from reagents removal of lead removal of iron Methylarenes... 

---