| Popis: |
In the condensation of chloral and chlorobenzene in sulphuric acid to yield DDT, the yield of DDT is increased and the rate of formation of DDT decreased by (1) decreased sulphuric acid concentration, (2) decreased molar amount of sulphuric acid, and (3) lowered temperatures. Reversible sulphonation of chlorobenzene is the major side reaction; the presence of 4-chlorobenzene-sulphonic acid reduces the extent of this reaction. Increased yields (based on chloral) can be obtained by using excess chlorobenzene. A mechanism is proposed involving 1-(4-chlorophenyl)-2,2,2-trichloroethanol, which has been isolated from the reaction, and 1-(4-chlorophenyl)-2,2,2-tricholorethyl bisulphate, whose barium salt reacts with chlorobenzene in sulphuric acid to give DDT. |
