2G8 PROCEEDINGS OF THE AMERICAN ACADEMY 



As the chlorine compounds used by Beilstein and Ivuhlberg, Ber- 

 lin, and Sintenis were all made by the action of chlorine on toluol in 

 the cold, and must therefore have contained the corresponding ortho- 

 compounds,* a revision of their work is necessary. 



Parachlorbenzaldehyde, C 6 H 4 C1C0H, was made by boiling 10 grs. 

 of parachlorbenzylbromide, melting-point 48^°, with 14 grs. of plumbic 

 nitrate and 100 grs. of water for three days in a flask with a return- 

 cooler, which was kept full of carbonic dioxide during the boiling and 

 subsequent distillations to prevent oxidation of the aldehyde by the 

 air. The aldehyde, separated by distillation from the plumbic bro- 

 mide formed, solidified in the cooler in long white needles, which 

 were purified by solution in acid sodic sulphite and filtering ; the 

 filtrate concentrated by evaporation deposited on cooling crystals of 

 the double salt of the aldehyde and acid sulphite, which were washed 

 twice with cold alcohol, dried, dissolved in a small quantity of hot 

 water, and decomposed by distillation with solid sodic carbonate. 

 The pure aldehyde, thus obtained, was dried over sulphuric acid in 

 an atmosphere of carbonic dioxide and analyzed. 



0.2112 gr. gave on combustion 0.4613 gr. C0 2 and 0.0680 gr. H 2 0. 



Calculated for C 7 H fi C10. Found. 



Carbon 59.78 59.56 



Hydrogen 3.56 3.57 



Properties. Long white needles melting at 47|°, which sublime 

 very easily ; slightly soluble in water, very soluble in alcohol, ether, 

 benzole, carbonic disulphide, and glacial acetic acid. Potassic perman- 

 ganate oxidizes it rapidly, air slowly, converting it into parachlorben- 

 zoic acid. 



The following substituted aldehydes were prepared from the cor- 

 responding bromides by the same method. In solubility they all 

 resemble the parachlorbenzaldehyde. 



Parabrombenzaldehyde, C G H 4 BrCO IT. 

 0.5000 gr. of the substance gave on combustion 0.8268 gr. C0 2 and 

 0.1298 gr. II 2 0. 



* These Proceedings, Vol. XIV. p. 54. 



