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COLOUE AND CHEMICAL CONSTITUTION. 
Part IV. — The Eemaining Phthaleins. 
By James Moie, M.A., D.Sc, F.I.C. 
In continuation of the systematic examination of the absorption-spectra 
of the phthaleins described in the three earlier parts of this work (1917), I 
have now prepared the phthaleins of all the remaining phenolic substances 
which are obtainable or capable of being made in South Africa. The 
following are the data observed in these new substances : 
A. Direct Substitution-products of Ordinary Phenol- 
PHTHALEIN. 
(1) a-anthrol-phthalein, from a-anthrol (Journ. Chem. Soc. Lond., 1916, 
p. 774) and phthalic anhydride, gives a brownish-green solution in alkali 
possessing an olive-green fluorescence. Its absorption-band is very near the 
red end, and can only be seen by use of direct sunlight, the centre being at 
about X 740. In cone. HoSO^ the band is broader and has its centre about 
A 720. 
(2) PJienol-a-anthrol-phthalein, from anthrol and oxybenzoylbenzoic acid, 
gives a greenish-blue colour in alkali. The centre of the absorption-band is 
at X 628. This substance is the (mono) xylylidene* derivative of phenol- 
phthalein, and is interesting as showing the greatest displacement of the 
absorption-band observed (a diminution of frequency of 13 per cent, for the 
single Cj^Hg group which constitutes the difference between anthracene and 
benzene). In the case of phenol-a-naphtholphthalein the fall of frecj[uency 
is 9*5 per cent, for the single butylidene group, which constitutes the 
difference between naphthalene and benzene. In cone. II0SO4 the above 
anthrol compound is purplish blue, with its band at A 611. 
(3) Phenol metacresolphthalein or metamethyl-jjhenolphthalem is purplish- 
pink in alkali, the band being at X 569. In II2SO4 the colour is salmon and 
the band at A 526. In connection with metacresolphthalein, described in 
Part I, I have now to issue a correction. The centre of its absorption-band 
as it X 584, not x 590. The specimen examined last year contained a trace of 
thymolphthalein, which caused a broadening of its band and a mis-estimate 
of its centre. 
* Xylylidene is naphthalene minus CH CH. 
