338 CHEMICAL DISCOVERY AND INVENTION 



barbituric acid. Barbituric acid, otherwise known to the chemist 

 as malonyl-urea, has the formula 



XNH C0\ 



co<; >CH 2 



\NH CO/ 



Its sodium salt is used medicinally under the name medinal. 



Malonyl-urea has an interest apart from its use in medicine, 

 arising from its relationship on the one hand to uric acid, an 

 important excretory product of the animal organism, and on the 

 other to theobromine and caffeine, the bases found respectively 

 in cocoa and tea or coffee. 



Formula of 



Uric Acid. 



NH-CO 



Theobromine. 



NH-CO 



Caffeine. 



N(CH 3 )-CO 



CO C-NH CO 



/CO 

 NH-C-NH N(CH 3 )-C-N 



C-N(CH 3 ) CO C-N(CH 3 ) 



N(CH 3 )-C-N 



All these compounds have been produced synthetically from 

 purely chemical materials and independently of animal or 

 vegetable agency. 



Among the many synthetical products which have become 

 familiar in our own time is saccharin, a compound which is re- 

 puted to have a sweetening power four to five hundred times the 

 sweetness of cane sugar. Saccharin, or gluside as it is called in 

 the British Pharmacopoeia, is orthosulphamido benzoic anhydride 



CO 



It is produced by a series of operations which have for starting 

 point the hydrocarbon toluene obtained from coal-tar. It is 

 used as a substitute for sugar in the diet of patients suffering 

 from diabetes and other disorders. 



All the preceding compounds and many others are officially 

 recognised as medicinal agents by the General Medical Council 



