SYNTHETICAL DRUGS 579 



The synthetical hypnotics fall into three groups : (i) those 

 containing halogens ; (2) those containing alkyl groups and 

 particularly^ the ethyl group ; (3) those containing aldehydic or 

 ketonic groups. Some hypnotics owe their soporific properties 

 to a combination of these characteristics. 



Isopral (trichloro/sopropyl alcohol) is an example of an alcohol 

 containing chlorine, recommended by the Bayer Company as 

 a substitute for chloral hydrate. Isopral is more efficient than 

 chloral and is freer from the depressing effects of the latter. 

 Moreover, it is devoid of any cumulative action or unpleasant 

 after-effects. 



Diethylbarhitiiric acid (XXI), also known as veronal, may be 

 regarded as an example of a hypnotic containing alkyl groups. 

 It may be produced by condensing urea (carbamide) with either 

 diethylmalonyl chloride or ethyl diethylmalonate, and many 

 other methods of preparation are being patented even at the 

 present time. Veronal is a colourless inodorous crystalline 



CO . fci Hi . NH CO - NH 



/ ■ \ / \ 



C(C,HA + CO -> C(C.,H,)3 CO + 2HCI 



\ / \ / 



CO.; CI Hj.NH CO - NH 



XXI. 



powder melting at i9i°C, and dissolving in 12 parts of boiling 

 and in 145 parts of cold water. It is a very satisfactory hypnotic 

 and sedative, rapid in its action and free from untoward sequelae ; 

 it has no disturbing effect on the heart or respiration. Fischer 

 and Mering, who discovered veronal, have since suggested the 

 employment of dipropylbarbituric acid under the name of 

 proponal. This substance is also very rapid in its action, doses 

 of o'2 gram inducing sleep in from fifteen to forty minutes. 



Hedonal is a compound of comparatively simple structure 



^^^)CH . O . CO . NH2 which is advocated by the Bayer Com- 

 pany as a safe soporific. Experiments have shown that this 

 compound is completely oxidised in the system to water and 

 carbonic acid, and it is accordingly quite devoid of any cumulative 

 action. It is indicated in cases of sleeplessness due to mental 

 strain or occurring in the course of neurasthenia or hysteria. 

 When a prolonged use of hypnotics is required it serves as 

 a useful alternative to the other soporifics. 



