The invention discloses a 5-
arylene barbituric acid derivative, a preparation method of the derivative and a magnetic acidic nanomaterial catalyst for its preparation, and belongs to the technical field of organic 
chemical synthesis.  In the preparation reaction of the present invention, the 
molar ratio of aromatic aldehydes to 
barbituric acid or 
thiobarbituric acid is 1.0 to 1.4:1, and the 
molar amount of the magnetic acidic nanomaterial catalyst is 7 to 12% of the aromatic 
aldehyde used, in milliliters.  The volume of reaction 
solvent water in millimoles is 4 to 7 times the 
molar amount of aromatic 
aldehyde in millimoles, the 
reaction temperature is 80 to 85°C, and the reaction time is 4 to 14 minutes. After the reaction is completed, use a 
magnet to absorb the catalyst while it is hot.  The remaining reaction solution was cooled to 
room temperature and filtered with suction. The filter residue was washed with 
ethanol and dried under vacuum to obtain the 5-
arylene barbituric acid derivative.  The invention has the characteristics of low catalyst loss, high recycling times, simple and convenient operation of the entire preparation process, high degree of greenness, etc., and is convenient for large-scale industrial application.