324 
SCIENCE. 
chloronitrophthalic acid C 0 Ha Cl (NOa), j cooh 
(A tterberg). 10 
IV. This same monochloronaphthalinetetrachloride 
yields on saponification with alcoholic potash the a 
trichloronaphthaline C 6 H 4 (C 4 Cl s H) melting at 8i°, 
and this, by oxidation, produces trichloronitrophthalic 
acid. C (NO a ) CI 3 j cooh - (Widman.* 3 ) 
V. Mononitronaphthaline C a H 3 (NOa) (C 4 H 4 ) pro- 
duces, by oxidation with chromic acid, nitrophthalic acid 
Co H 3 (NOa) j cooh melting at 212°, which can also be 
obtained directly from phthalic acid by the action of nitric 
acid. (Beilstein and Kurbatow. 14 ) 
On the other hand, naphthylamine C 0 H 3 (NH 2 ) 
(C 4 H 4 ) which corresponds to this nitronaphthaline may 
be oxidized, by means of permanganate, into ordinary 
phthalic acid 16 (Graebe. 16 ) Co H 4 j cooh’ 
Binitronaphthol Co H (OH) (NOa)a (C 4 H 4 ), produced 
from naphthylamine, also yields, by oxidation, phthalic 
acid. (Liebermann and Dittler. 1 ’) 
This last proof is indisputable, as it shows conclusively 
that no matter which half of the naphthaline ring is 
oxidised the same phthalic acid results. Naphthaline 
must therefore possess an absolutely symmetrical struc- 
ture, and hence the following formulae, proposed by 
Wreden, lose every support. 
C H 
C H 
\ / 
C H 
C— C H— CH 
II I II 
C— C H— CH 
C H 
Berthelot, 18 and latter Ballo,' 9 deduced from the for- 
mation of naphthaline from benzol or styrol and aethylene 
the formulae : 
CH— CH— C-CH— CH 
1 I II I 1 
CH— CH— C— CH— CH 
The above formula explains very clearly, the corres- 
ponding syntheses and is also symmetrical but it cannot 
be accepted because it would give the following formula 
for benzol: 
CH— CH— CH 
II I II 
CH— CH— CH 
in which the six hydrogen atoms have not all the same 
value. The univalence of the same is positively shown 
from the examination of Ladenburg, Hubner and Peter- 
mann, Hubner and Wroblewsky. 
ISOMERISM OF THE NAPHTHALINE DERIVATIVES. 
Faraday 211 observed while investigating the sulpho-acids 
of naphthaline that two isomeric mono derivatives were 
formed. Since then an entire series of others have been 
discovered. Almost all of the biderivatives exist in two 
modifications, and the number of isomers among the 
higher substitution products is very numerous. The for- 
formula now used to represent naphthaline explains this 
fact in a very satisfactory manner. 
One observes, therefore, that it is not indifferent whether 
the hydrogen consecutive to the four combining carbon 
atoms are replaced or whether the four combining posi- 
tions furthest removed from them, are replaced. On the 
other hand it is evident that the hydrogen atoms in 
groups of four possess equal values. In order to distin- 
guish between these two varieties of hydrogen atoms 
Merz 21 has designated them by the letters a and ft, and 
distinguishes the isomeric series as the a and /S deriva- 
tives. He did not, however, state to which of the posi- 
tions of the hydrogen atoms belonged the a and which 
the p series. 
Wichelhaus, 22 soon after, forming a theory on the analogy 
between the a naphthol with phenol, assumed that the sub- 
stituting hydrogen atoms were combined with the carbon 
atoms in both compounds alike (2. e. in a similar manner) 
and hence the a position must correspond to the com- 
bining place furthest removed from the carbon a'.oms. 
Especially as they are more like the benzol carbon atoms. 
Subsequently when it was shown that naphthachinon 
was an a — a derivative (Liebermann and Dittler 23 ) and 
the para (1, 4) position of ordinary chinon was definite- 
ly settled, the notation was changed. 
a a 
a a 
PRESENT. 
This demonstration is untenable however, for Sten- 
house and Groves, 24 have discovered a second napththa 
chinon, viz. : the P, which likewise contains the two 
atoms of oxygen in the same ring ; hence it follows that 
there are chinons which do not have their oxygen atoms 
in the paraposition (1, 4). Consequently the constitu- 
tion of ordinary naphthachinones, as well as the position 
of the a and P atoms again becomes doubtful. Fortu- 
ately however other experiments, made under different 
conditions, permit the final answering of this question. 
We have seen how Beilstein and Kurbatow 26 , by the 
oxidation of nitronaphthaline, which is an a derivative, 
have obtained ordinary nitrophthalic acid, melting at 
212 0 . Theoretically, there are but two isomeric nitro- 
phthalic acids possible, both of which have been prepared. 
I. 
II. 
NO, 
COOH 
NO, /A 
COOH 
V 
COOH 
V 
COOH 
The first melts at 212° ; the other, discovered by Q. 
Miller, melts at 165°. 
The latter, according to the exact researches of this 
investigator, corresponds to the oxyphthalic acid of Baeyer. 
On the other hand, Schall, 21 , in the course of his research- 
es on the hydroxylated benzoldicarbon acids, demonstrat- 
13 Loc. Cit., p. 59. Soc. Chim., Paris, XXVIII, 505, (1877). 
14 Deutsche Chem. Ges. XII. 688, (1879). 
16 Naphthylamine gives, with potassium chromate and sulphuric acid, 
phtalic acid and naphtachinon, (R. & N.) 
16 Private papers. 
17 Ann. Chem., CLXXXIII, 228, (1876). 
18 Ann. Chem. Pharm. CXLII, 251 (1867.) Comptes Rendus LXIII, 
788 and 834. 
19 Das Naptalin und seine Derivate. 
20 Ann. Chim. Phys. XXXIV, 164. 
21 Zeitschrift fiir Chemie, NF. IV, 399 (1868). 
22 Ann. Chem. Pharm. CLII, 311 (1869.) 
23 Ann. Chem. CLXXXIII, 228 (1876.) 
24 Ann. Chem. Pharm. CLXXXIX, 145 (1877.) 
26 Deutsche Chem. Ges. XII, 688 (1879.) 
20 Deutsche Chem. Ges. XI, 1191 (1878.) 
27 Deutsche Chem. Ges. XII, 816 (1879.) 
