112 
Transactions of the Royal Society of South Africa. 
yield mixed phtlialeins of a new type, although phthalic anhydride does 
not condense with these substances. Thus coumarine, quinosol, dimethyl- 
aniline, and to some extent even menthol, yield phthaleins with this acid ; 
in fact, probably any ring compound with — OH or — NHg, either free or 
substituted, will react in this way, provided that it has a free para- or 
ortho-position. The following scheme represents the combination in the 
simpler of the two cases, the para-position being the preferred one : 
(1) HO— <^ \_C0— <^ y + <^ \— NMeg 
p-oxybenzoylbenzoic acid dimetliylaniline 
or 
j9-oxybenzophenone-o-carboxylic acid. 
= HO-/— \-C<\— > 
\ ^ / ^O CO + H2O 
Me,N<;^ 
Phenoldimethylaniline-plithalein. 
Unfortunately for my priority, the principle of this synthesis has in the 
meantime been discovered independently in the United States, Messrs. 
Orndorff and Murray (' Journ. Amer. Chem. Soc' April, 1917) having 
published the preparation of several of my mixed phthaleins and thus 
evidently anticipated me by a few months. They did not, however, 
" spectroscope " their compounds. 
Table I gives the results of my investigation. 
It may be noted that (1) phenolcoumarinphthalein is a direct derivative 
of ordinary phenolphthalein, being its o-acrylic acid cotnpound, the acrylic 
group — CH : CH • COqH having practically the same effect on the colour 
as a methyl group ; (2) quinosol is 8-oxyquinoline, i. e. with the — OH 
group in a different ring from the nitrogen ; the pyridine ring has less 
effect on the colour than the benzene-ring, comparing the quinosol- with 
the a-naphthol- compound ; (3) the hydrogenated rings of menthol and 
tetrahydronaplithol have much less effect than the corresponding thymol 
and naphthol rings, but owing to one attachment of the tetrahydronaplithol 
ring being meta to the — OH (see Part I), the effect is greater than that 
of a powerful group (e. j/. — OCH3) in the orj^/^o- position ; (4) the effect of 
the phenolic — OH having to take up the or^/^o-iu stead of the usual para- 
position to the central carbon is a greatly increased shift of the colour or 
lowei'ing of frequency, e. g. the /:^-naphthol derivative. 
It is probable that the absorption-band of di-/i-naphtholphthalein 
(from /3-naphthol and phthalic anhydride) is right off' the visible spectrum, 
which accounts for it not having been recognised, 
The mixed aminophthaleins are remarkably sensitive to excess alkali, 
