$H 



SCIENCE. 



acid C 6 H„ CI (NO.), 



COOH 

 COOH 



chloronitrophthalic 

 (Atterberg). 10 



IV. This same monochloronaphthalinetetrachloride 

 yields on saponification with alcoholic potash the a 

 trichloronaphthaline C 8 H 4 (C 4 Cl 3 H) melting at 8i°, 

 and this, by oxidation, produces trichloronitrophthalic 

 acid. C (N0 3 ) CI, j£ggg. (Widman.'s) 



V. Mononitronaphthaline C„ H 3 (N0 3 ) (C 4 H 4 ) pro- 

 duces, by oxidation with chromic acid, nitrophthalic acid 

 C« H 3 (N0 2 ) Jcooh 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 6 H 3 (NH>) 

 (C 4 H 4 ) which corresponds to this nitronaphthaline may 

 be oxidized, by means of permanganate, into ordinary 

 phthalic acid 15 (Graebe. 16 ) Ce H 4 \ c8oh' 



Binitronaphthol C 6 H (OH) (N0 2 ) 3 (C 4 H 4 ), produced 

 from naphthylamine, also yields, by oxidation, phthalic 

 acid. (Liebermann and Dittler. 11 ) 



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. 



CH C H 



H C 

 HC 1 



-1 — C H 3 

 i I 

 II -CH 



c — c 1 



— C H 



HC 



I 

 H C 



C— CH— CH 



II I II 



C— C H— CH 



C H 



C H 



Berthelot, 18 and latter Ballo, 19 deduced from the for- 

 mation of naphthaline from benzol or styrol and aethylene 

 the formulae : 



CH— CH— C-CH— CH 



II I II I II 



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 tollowing formula 

 for benzol: 



CH— CH— CH 



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, Hiibner and Peter- 

 mann, Ilubner and Wroblewsky. 



ISOMERISM OF THE NAPHTHALINE DERIVATIVES. 



Faraday"' 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- 

 tormula now used to represent naphthaline explains this 

 fact in a very satisfactory manner. 



ia I p ,. Soc. Chim., Paris, XXVIII, 505, (1877). 



'« Deutsche XII, 688, (187,,). 



iphthylamine gives, with potassium chromatc and sulphuric acid. 

 .■ id and naphtacbinpn, <H. tk N.) 

 '* Private ps 



inn. ( hem., CI.XXXIII, 328, (1876). 

 "Ann Chem Pharos. CXI. II, 151 (1867.) Comptes Rendus I. XIII, 



788 and 8 44. 



1 ' 1 1.1, Naptalin und *cine Den 

 30 Ann Chun. I'hys. XXXIV, 164. 



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 p, and 

 distinguishes the isomeric series as the a and p 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 (i.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 (i, 4) position of ordinary chinon was definite- 

 ly settled, the notation was changed. 



P P 



P P 



FORMER. 



A? 



This demonstration is untenable however, for Sten- 

 house and Groves, 24 have discovered a second napththa 

 chinon, viz. : ihe 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 25 , by the 

 oxidation of nitronaphthaline, which is an « derivative, 

 have obtained ordinary nitrophthalic acid, melting at 

 212 . Theoretically, there are but two isomeric nitro- 

 phthalic acids possible, both of which have been prepared. 



I. 



NO, 



-COOH 



COOH 



NO, 



II. 



A 



COOH 



-COOH 



The first melts at 21 2° ; the other, discovered by O. 

 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, H , in the course of his research- 

 es on the hydroxylated benzoldicaibon acids, demonstrat- 



21 Zeitschnft flir Chemie, NK. IV, 399 (1868). 



»» Ann. Chem. l'harm. CLII, 311 (1869.) 



" Ann. Chem, CI.XXXIII, 228 (1876.) 



" Ann. Chem. Pharin. CLXXXIX, 145 (1877.) ' 



■• Deutsche Chem. Oes. XII, 688 (1879.) 



'■" Deutsche Chem. Gcs. XI, nyi (1878.) 



" Deutsche Chem. Oes. XII, 8:6 (1879.) 



