134 Transactions of the Boyal Society of South Africa. 
He'ptahronio^heiiolphthaleins. 
Position of bromine 
atoms. 
Source. 
Observed band- 
centre. 
Calculated from 
position-law. 
a-h {?)-d-f-g-j-h 
Tribromo-compoiind 
X 609 vague 
r X 605 6 
1 X 612 c 
The possible number is the same as that of thepenta-derivatives, viz. 118. 
The possible number of octobromo-compounds is the same as that of the 
tetra-compounds, viz. 80, and so on with the nono-, deca- and hendeca- 
compounds. The substance a-h-c-d-f-g-j-k has been made in America, 
but I find it difiicult to make a perfectly pure preparation. The figure 
given in Part I of this work, viz. X 608, is certainly too low, since its band- 
centre should be at x 613 or x 614 by calculation. 
A perchloro-derivative of phenolphthalein has been mentioned in Part IX, 
and is green in alkali with band-centre x 642. The corresponding bromo- 
compound would have its band-centre at about x 647.* The theory for a 
decabromophenolphthalein having all the positions except a and d occupied 
is X 649, and it is reasonable to assume, from the analogy of phthalic acid, 
that the a- and cZ-positions would not be attacked by chlorine at the low 
temperature of boiling CHCI3. This green substance is therefore hcefghijhl- 
decachlorophenolphthalein. 
Another chlorine derivative which is new is monometachlorophenol- 
phthalein, made from OBBA and metachlorphenol with H^SO^ at 100° C. 
Its band-centre was found to be at x 564 only, and the band was broad. 
The theoretical figure is x568§, and it is possible that the substance was 
contaminated with o-p-phenolphthalein, x 559, arising from the OBBA alone. 
It is not possible to distinguish two band-centres unless they are at least 
7 units in x apart. 
The corresponding monometaiodophenolphthalein was made in an 
analogous manner. Its band in alkali was at first broad, but on 
standing became narrow at X568^ (theory 569^). This substance was next 
perbrominated, and the penta-derivative (/-^-j-A;-tetrabromo-e-iodophenol- 
phthalein was found to have X600, which agrees with theory (554 -f 30 
+ 151). 
A penta-iodo-phenolphthalein was obtained by treating the barium salt 
of phenolphthalein with excess of warm solution of iodine in KI. Its band- 
centre was at x596, which differs from that of the /-^-j-A^-tetriodo-compound 
(which is first formed) by 10 units. I infer, since iodination in the a-position 
* From the law given in Part IX. 
