Catalytic synthesis of dimaleates with ammonium ferric sulfate

Dimaleates such as dibutyl maleate, diamyl maleate, di-iso-amyl maleate, dioctyl maleate are synthesized using ammonium ferric sulfate as catalyst. The experimental result shows that in the synthesis of the dimaleates, the catalytic activity of the solid catalyst is high, the reaction conditions are mild, the process is simple and the product is very pure. Within two hours the total yield is over 98% respectively.