2,3-Dihydro-1,4-dithiino[2,3-C]furan-5,7-dione10489-75-5100 % similar 3,4,5,6-Tetrahydrophthalic anhydride2426-02-038 % similar Isoprothiolane50512-35-135 % similar Dichloromaleic anhydride1122-17-435 % similar Dimethylmaleic anhydride766-39-235 % similar Methacrylic anhydride760-93-031 % similar