132 Transactions of the Royal Society of South Africa. 
Dihromo phenolphthale ins . 
Position of bromine 
atoms. 
Method of formation. 
Observed band- 
centre. 
Calculated from 
position-law. 
a-d 
3-6-dibromplithalic acid ex 1-4- 
X 573 
X 574 
dibromnaphth alene 
h-c (?) 
4-5 (?) dibromphthalic acid ex 
X 564 
X 563 
silver phthalate + 261*2 
a-c 
3-5 dibromphthalic acid ex anthra- 
X 571 
X 572 
nilic acid 
f-9 
OBBA and 2-6-dibromphenol 
X 570 
X 570 
f-3 
Phthalic acid and 2-bromophenol 
X 569 
X 569 
The number of tribromopheuolphthaleins possible is much larger, viz. 54, 
but if, as suggested above, those which contain the cZ-position and not the 
a-position be eliminated, there remain 42 possible different spectra for the 
isomers. It will be sufficient to enumerate these, since their method of 
formation is obvious by what has gone before. They are : 
a- 
-h-c 
a- 
-d~f 
a-e-i 
b-e-i 
c-e-i 
e-f-j 
a- 
-h-d 
h- 
-c-f 
a-e-j 
h-e-j 
c-e-j 
e-g-i 
a- 
-c-d 
a- 
-c-f 
h-f-g 
<^-f-9 
e-g-j 
a- 
-d-e 
a- 
h-f-j 
e-h-i 
h- 
'C-e 
a- 
-e-f 
h-e-f 
c-e-f 
e-h-j 
a- 
~c-e 
a- 
-e-g 
h-e-g 
c-e-g 
e-f-h 
e-j-h 
a- 
-h-e 
a- 
-e-h 
h-e-h 
c-e-h 
e-f-i 
f-g-j 
Tribromophe7iol])hthaleins. 
Position of bromine 
atoms. 
Method of formation. 
Observed band- 
centre. 
Calculated from 
position-law. 
a-h-d \ 
a-c-d J 
f-9-j 
3-4 (or 5)-6-tribromophthalic acid 
and phenol 
Dibromo derivative of OBBA and 
orthobromphenol 
j>576 insepj 
577 
irablej^^^ 
577 
Only these two could be prepared. In all the other cases tried the 
reaction went abnormally, giving substances which from the behaviour of 
phenolphthalein when heated with cone. HoSO^, and from their spectra, may 
be identified as isomeric varieties of dibromoxyanthraquinone. 
There appear to be 80 possibilities for tetrabromophenolphthalein if the 
(^-position is not counted unless the a-position is present. The first 7 are 
abed, abce, ahcf, abde, ahdf, acde and acdf; then follow 28 made by combining 
the series ef, eg, eh, ei, ej, fg, fh with the series ab, ac, ad, be ; then follow 
30 made by combining the series efg, efh, efi, efj, egi, ehi, egj, ehj,fgi,fgj 
successively with a, b and c. The remainder are efg combined with h, i, j ; 
