TETRABROM < HD] P 1 1 E NO-QU] NON E. 323 



A. The starting-material, tetrabromo-diphenol, is made by 

 dissolving purified diphenol (4-4' dihydroxy-diphenyl) in hot 

 glacial aortic acid, and adding, all at once, a solution of 8^ 

 atomic equivalents of bromine dissolved in warm acetic acid. 

 Tetrabromo-diphenol crystallises out as soon as the evolution 

 o\ I Mir is ended, but the mixture is kept warm for an hour. 

 Thereon sufficient of a saturated solution of Na 2 S0 3 is added to 

 decolourise the bromine left ( otherwise on dilution some of the 

 quinone is formed ) ,and the mixture then diluted and filtered. After 

 recrystallisation from alcohol, tetrabromo-diphenol melts at 266°. 

 Analysis by my method* gave Br=63.62%. Theorv for 

 C ls H 6 Br 4 2 =6 3 .72. 



Tetrabromodiphenol-diacetate was made by use of acetic 

 anhydride and potassium acetate. Its melting-point was found to 

 be 247 , rather higher than that found by Magatti. Tetrabromo- 

 diphenol-dibensoate is new. Made by the Schotten-Baumann 

 method. White granules, appreciably soluble in ethyl acetate and 

 acetone only: melting-point 245 . Analysis gave Br=45.62%. 

 Theory for C., (; H J! O l Br 1 =45.07. 



What appears to be tribromo-diphenol is obtained from the 

 mother-liquors of the tetra-compound when sufficient time for 

 reaction has not been given: m.p. 150 ; comparatively soluble; 

 otherwise behaves in the same way as the tetra-compound. 

 Analyses inconsistent, from 55 to 58% Br. 



B. Configuration of tetrabromo-diphenol. — (1) On diges- 

 tion with an excess of a mixture of KC1G 3 and dilute 

 hydrobromic acid, the substance is oxidised to 2-6 

 dibromo-quinone of melting point 130 , which is also 

 obtained when tetrabromo-diphenol is boiled in benzene with 

 a large excess of PbO 2 (see below for new method of preparing 

 dibromo-quinone) ; (2) bromine and soda produce small quantities 

 of 2-4-6-tribromo-phenol ; (3) oxidation of tetrabromodiphenol- 

 diacetate with Cr() 3 in acetic acid near the boiling-point of the 

 latter, followed by hydrolysis of the acetyl group from the gummy 

 product, gives a sparingly soluble acid, which was identified as 

 ^-^-dibronw-^-osybciLcoic acid. The specimen, not quite pure, 

 melted at 262^. This substance was discovered by Kerp (see 

 Beilstein), and I have also obtained it by oxidising the diacetate of 

 tetrabromo-phenolphthalein in the same way as above. I also 

 made a quantity of this substance, starting by treating a saturated 

 water solution of paracresol with bromine water, acetylating the 

 2-6-dibromocresol formed, and oxidising it with Cr03 as above to 

 change — CH 3 into — C0 2 H: finally the acetylated acid was 

 hydrolysed as before and purified, but I was unable to obtain a 

 higher melting-point than 262 . The acid resembles tetrabromo- 

 diphenol, but gives no colour-reactions on oxidation. On re- 

 acetvlating it and recrystallising the product, 3-5-dibromo-4 

 acetoxy-benzoic acid was obtained in soft white granules, m.p. 

 187 (not sharp). 



* Proc. Chem. Soc, 1906, p. 263 (and 1907). 



