Malonyl urea

Barbituric acid can be considered as a cyclized malonic acid diamide (malonyl-urea). It is therefore a cyclic diketone that may be classified, in the sense of the compounds discussed in Section 12.6, as a coupling component with a methylene group activated by two carbonyl groups in the a- and a -positions. The reaction with arenediazonium salts was studied by Nesynov and Besprozvannaya (1971). These authors obtained coupling products (in good yield) that they considered to be arylhydrazones. Coupling with 4-(phenylazo)benzenediazonium chloride was studied by Chandra and Thosh (1991). The lH NMR spectra of these compounds are consistent with the arylhydrazone structure 12.68. 

Barbitone. (Barbital, veronal, 5 5-diethyl malonyl urea) The exclusion of water is also paramount in this step (use drying tubes, etc.). 30 kilos of dry urea and 76.5 kilos of the above malonate (dry diethyl diethyl malonate) are placed in the reaction vessel and stirred very well. To this mixture is added a solution of hot (75°) sodium ethylate (18 kilos of clean sodium metal in 270 liters of dry ethanol) and the mixture is brought to a boil with good stirring. The alcohol is removed with the boiling action (the reaction vessel is equipped with a slanted vapor condenser) and the mixture becomes more viscous. The alcohol (ethanol) is distilled out completely and the heat is then removed. The residue left behind should be a creamy white powder. 

BARBITURATES. Barbiturates are 5,5 -disubstituted derivatives of barbituric acid (malonyl urea). Barbituric acid does not have hypnotic properties, but its derivatives do, and are widely used in medicine as hypnotic-sedatives. Because of their widespread use, the intentional and unintentional abuse of these drugs is most frequent, and most larger hospitals and medical centers have clinical screening and analytical procedures established to determine such compounds in the body fluids of patients. 

Barbituric acid malonyl urea C0 (NHC0)2 CH2-2H20 164,12... 

Many cyclic ureides are derived from malonic acid or malonic esters. They are collectively known as barbiturates because of their relationship of malonyl urea or barbituric acid. Barbituric acid is prepared by the following two methods ... 

There are a number of compounds which do not essentially possess the malonyl urea or barbiturate structure but exhibit marked and pronounced hypnotic-sedative activity veiy similar to that of the barbiturates. Like barbiturates these are habit-forming to varying degrees. They may be grouped together on the basis of their basic structures, namely ... 

C. J. Umberger and G. Adams, Identification of Malonyl Urea Derivatives. Infrared Absorption in Toxicological Analysis, Anal. Chem. 24,1309,1952. 

N-dealkylation is also possible. An example of this is the removal of the methyl at position 3 of hexobarbital. The heterocyclic ting of the barbiturates does not usually participate in their metabolism. However, cleavage of the (1-6) bond is possible and it produces malonyl urea derivatives. 

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