ON ISOMERIC NArnXHALENE DEEIVATIVES. 265 



Fifth Report of the Committee, consisting of Professor Tilden and 

 Professor Armstrong {Secretary), appointed for the pw^ose of 

 investigating Isomeric Naphthalene Derivatives. {Drawn up 

 by Professor Armstrong.) 



The isomeric d'uMoronaiMlmlenes. — Since the publication of the pre- 

 vious report Mr. Wynne and the writer have completed their examination 

 of the dichloronaphthalenes. As mentioned in the third report, no 

 fewer than twelve isomerides were reputed to exist ; one of these, however 

 — strange to say, the a-modification, the oldest member of the set — has 

 proved to be non-existent as a distinct isomeride, being a mixture of two 

 others inseparable by the ordinary methods of crystallisation ; while 

 another has been shown to have been improperly ranked as a dichloro- 

 derivative, being a trichloronaphthalene. The remaining ten have been 

 characterised and their constitution determined by logical and consistent 

 arguments, which leave no doubt that they actually are the ten dichloro- 

 naphthalenes which, according to theory, can exist if the simple double 

 hexagon formula for naphthalene be adopted. 



The formulte of the ten dichloronaphthalenes are given in the table 

 below, those of the acids into which they are converted on sulphonation 

 being given in the second column of the table, and those of the corre- 

 sponding trichloronaphthalenes in the third. In this table S is printed 

 for SO3H ; the melting points of the chloride and amide of the acid are 

 indicated below the symbol of the acid.' 



aa-BLldoronapldlialenes. 



CI CI CI 



/\/\ s/\/\ ci/\A 



Ml - Ml - i 



W ^'Y ^MT 



M. p. = (;7°o. SO..CI, m. p. = 132°. M. p. = G6°. 

 SOjSH,, m. p. = 244°. 



Ci CI CI CI CI C'l 



/\/\ /x/\ /Y^i 



'\/x/ Vx/ \yyf 



« Ul 



M. p. = 82°. S0„C1, m. p. = m°. M. p. = 131°. 

 .SO',NH„ m. p. = 228°. 



CI CI 



CI Cl 



SO.Cl, m. p. = 139° 5. M. p. = 103° 

 bOnNH.,, m. p. = 20-1°. 



-^ 



Cf. Chen. Soc. rrocccdin/jn, 1S90, pp. 77-84. 



