Anaesthetic Properties of Some New N‐substituted and N,N'‐ disubstituted Derivatives of 5,5‐Diallyl‐Barbituric Acid.

Summary. A series of N‐substituted and N,N‐disubstituted derivatives of 5,5‐diallyl‐barbituric acid have been synthetized. Their chemical properties and ultra‐violet absorption spectra are reported. Their anaesthetic properties were investigated. The N‐substituted derivatives have lower potency and briefer induction time than the parent compound. The median hypnotic dose increases with the molecular weight. Derivatives with the longest duration of action have the smallest therapeutic index and vice‐versa. The duration of action of the N‐substituted derivatives are both longer and shorter than the parent compound. The N,N‐disubstituted derivatives are devoid of anaesthetic activity. At physiological pH, some barbiturates exist in the enol‐form, others in the keto‐form. There is no correlation between this phenomenon and hypnotic efficiency. By varying the acidity and solubility of the barbiturates examined, it was found that only weak acids with a solubility within certain limits have pronounced anaesthetic activity. The mechanism of action is discussed.