Thianthrene → Chlorothianthrene

Participants

Reaction Steps

Twenty parts of thianthrene dissolved in 142 parts of monochlorotoluene (a commercial mixture of about 50 percent ortho- and 50 percent para-chlorotoluene) were charged to a batch type stirred tank reactor together with 0.2 part of SbCl3. Chlorine was fed to the reaction mixture at about 0.35 parts/min. for a 4 hour period. The mixture was then cooled and 14.5 parts of chlorothianthrene were obtained which had 68.03 percent 2,3,7,8 -tetrachlorothianthrene. Part of this sample was recrystallized from tetrahydrofuran to produce 95.3 percent 2,3,7,8-tetrachlorothianthrene, melting point 250°-255° C. Another 3.7 parts were recovered as a second crop from the mother liquor, giving a total yield of 19.2 parts of chlorothianthrene. This second crop was low melting with 43.25 percent of the 2,3,7,8 -isomer indicating that the composition was a mixture of 2-chloro-, 2,7-dichloro-, and other isomers with 2,3,7,8-tetrachlorothianthrene.

Provenance & Evidence