agricultural and horticultural fungicide containing as an active ingredient the maleimide derivative application_number US 37080089 A description the maleimide derivative having the above mentioned general formula i can be prepared according to the following process a or b str5 in the above reaction formulae r 1 r 2 r 3 r 4 r 5 x 1 and x 2 are as defined in the general formula i according to the process a a corresponding acid anhydride ii is reacted with an amine derivative under reflux in an organic acid such as acetic acid or in a non protonic solvent such as toluene or xylene according to the process b the acid anhydride ii is reacted with the amine derivative iii at a temperature of from room temperature to the boiling point in a non protonic solvent for example an ether type solvent such as ether tetrahydrofuran or dioxane a benzene type solvent such as benzene or toluene an ester type solvent such as ethyl acetate or acetone to form a maleic acid amide derivative iv and the derivative iv is then reacted at a temperature of from 80 u00b0 to 200 u00b0 c in the absence of a solvent or in the presence of a solvent such as toluene xylene.