2-cyclobuten-1-one, 4,4-dichloro-2-(2-chloroethyl)- 4,4-dichloro-2-(2-chloroethyl)cyclobut-2-en-1-one InChI=1/C6H5Cl3O/c7-2-1-4-3-6(8,9)5(4)10/h3H,1-2H