THE ALUMNI JOURNAL. 



Thio-urea or CS sulfocarbamide is 



the base of thiosinamhie, an allyl-thio 

 carbarmide CS<CAT-tT ^ '" ^ remedy 

 employed in chronic cutaneous diseases. 



AROMATIC COMPOUNDS. 



We will now leave the fatty series or 

 methane derivatives, which are dis- 

 tinguished by an " open carbon chain " 

 for those of the " closed ring " or aroma- 

 tic compounds. Among the bodies which 

 form the transition to the aromatic group 



we have: HC— CH 



II II Furfurane. 

 HC CH 



O 



HC— CH HC— CH 



II li Thiophene. || || Pyrrol. 



HC CH HC CH 



S NH 



The one of greatest interest to us is 

 pyrrol, a constituent of coal-tar and 

 bone-oil. This forms the basis of zodo/, 

 (a substitute for iodoform), which is a 

 tetra-iodo-pyrrol, four hydrogen atoms 

 of pyrrol being replaced by iodine. 

 Pyrrol is also the mother substance of 

 antipyrin, in which one of the carbon 

 atoms of pyrrol is replaced by a second N 

 atom, two hydrogens b}^ methyl and a 

 third by phenyl CgHg an oxygen replaces 

 a hydrogen where the double linking of 

 two carbon atoms is dissolved to a single 



A combination of antipyrin with chloral 

 is designated as hypnal, or mono-or bi- 

 chloral antipyrin. With butyl-chloral it 

 combines to butyl hypnol. If one H is 

 replaced by I, iodopyrin results, combin- 

 ing the properties of both. 



If we introduce a methyl radical for a 

 hydrogen of the phenyl group in anti- 

 pyiin, a methylated-phenyl-dimethyl- 

 pyrazolon is obtained N — CrH^CHs 



0=C| 



IN— CH, 



HCI 



HC" 



0=C| 



o 



N 

 Vh 



HC= 



Di-methyl-phenyl- 

 |N — CH3 pyrazolon. 



Antipyrin. 



=C— CH, 



The salycylic acid salt of antipyrin is 

 called salipyyin. 



HC==C— CH3 

 This is better known under the name of 

 tolypyrin, an antipyretic. The salicylic 

 acid salt of this is called tolysal. 



BENZENE — DERIVATIVES PROPER. 



The aromatic compounds are derived 

 by substitution, from a nucleus consisting 

 of six carbon atoms, the simplest of which 

 is benzene CgHc. The structure of the 

 benzene nucleus is such, that six carbon 

 atoms form a closed ring-shaped chain, 

 the atoms joined alternately by single 

 and double bonds, each carbon being 

 linked to a hydrogen. The readiness 

 with which these hydrogens may be re- 

 placed will explain the existence of a 

 vast number of derivatives. Its structure 

 is symmetric, that is the six affinities of 

 the nucleus are of equal value. 



CH 



HCy\CH 



r ii 



HCX4/ CH 

 CH 



Any one hydrogen atom can be replaced 



by another atom or atomic group, hence 



the resulting compounds can exist in but 



one modification only, thus there can be 



but one chlor-benzene (CgH^Cl), one 



nitro-benzene CsH-NO.), one benzoic 



acid (CsHj-COOH) etc. 



Although the six hydrogen atoms in 



benzene are of equal value, it is clear 



that from the above figuie that each di- 



