272 



THE ALUMNI JOURNAL, 



FORMALDEHYDE. 



By Professor virgil Coblentz. 



The chemistry and pharmacy of form- 

 aldehyde form the subject of an interest- 

 ing article by Dr. Altschul in the Phar- 

 maceutische Centralhalle from which the 

 following is abstracted. Formaldehyde 

 was first prepared by A. W. Hofmann in 

 1867, in which the mixed vapor of methyl 

 alcohol and air was passed over a glow- 

 ing platinum spiral, this was later re- 

 placed by copper, and the vapors were 

 pas.sed into water, whereby moderately 

 concentrated solutions were obtained. 

 Grossmann, upon the addition of an al- 

 kali bisulphite, precipitated formalde- 

 hyde as a double salt (formaldehyde acid 

 sulphite of the alkali), the reducing 

 properties of which served as a photo- 

 graphic developer. Owing to the varied 

 applications of formaldehyde in the man- 

 ufacture of organic chemicals and colors, 

 various manufacturers sought for a more 

 economical method of preparation. In 

 i89o,Trillet a French chemist patented a 

 process in which large quantities of vap- 

 orized methyl alcohol mixed with air 

 were drawn by suction through large 

 copper pipes, which contained either 

 coke, charcoal or any porous material in 

 glowing condition. This brought about 

 the oxidation of the methyl alcohol to 

 formaldehyde, the vapors of which were 

 caused to pass into water where they 

 were absorbed. This process slightly 

 modified, has been patented in various 

 countries. Among the important syn- 

 theses in which formaldehyde is employed 

 in the coal tar industries, the following 

 may be cited; with one molecule of form- 

 aldehyde and two molecules of an aro- 

 matic base, di-amido-di-phenyl-methane 

 derivatives are formed, which with a third 

 molecule of a base, on oxidation, are con- 

 densed to tri-phenyl-methane deiivatives 

 which form the basis of many classes of 

 anilipe colors. This may be illustrated 



by the formation of para-rosaniline from 

 aniline and formaldehyde: 



Formalde- 2 inol. aniline Di-aniidodipheu}'!- 

 hyde. methane. 



+ H,0 



/C,H,NHo 

 HO— C— C„H,NH.,+ H,0 



p-rosaniline base. 



If toluidin (CgH^NH^CHs), the next 

 higher homologue of aniline be employed 

 in reaction b in place of aniline, the fuch- 

 sine bases are obtained. The application 

 of formaldehyde has been extended to 

 various other branches of the color in- 

 dustry. In the manufacture of synthetic 

 coal tar products, we find among its 

 various applications, the action of form- 

 aldehyde on phenol, whereby saligenin 

 (a decomposition product of salicin), is 

 obtained, which has lately been intro- 

 duced as a remedy for rheumatism. 



Thus:— 



CH 



HC 

 HC 



C— OH /H 



+ C— H^^ 



CH \0 



CH 



Phenol. 



CH 



Formaldehyde. 



HC C— OH 



/H 

 HC C— C— H 



\/ \0H 



CH 



Saligeniu. 



By interaction between gallic acid and 

 formaldehyde. Care obtained methylene- 

 di-gallic acid, the bismuth salt of which, 

 has been introduced by Mess. Merck, un- 

 der the title of Bismal, an intestinal as- 

 tringent. If in the above, tannic acid be 

 substituted for gallic acid, Tannoform is 

 obtained. 



