A mixture of 12.5 g of 2,2-dimethyl-l,3-dioxolan and 25 ml of glacial acetic acid is added to 10 grams of addition product (3). The mixture is then stirred and heated to 60ยฐC. The diazonium salt dissolves, and after 10 minutes, the reaction is completed. After working up as described above, 89.3 % of trimethylammonium fluoroborate and 51.9 % of 1,3,5-trichlorobenzene are obtained. To demonstrate the presence of the 4-acetoxy-2,2-dimethyl-1,3-dioxolan formed, another reaction mixture on the same scale was treated with 2 N hydrochloric acid and 50 m l of water; the mixture was agitated for 3 hours, and the acetone formed removed by vacuum distillation. After filtering off the precipitate of 1,3,5-trichlorobenzene, the filtrate was treated with a solution of 10 g ofp-nitrophenylhydrazine in 150 ml of 2 N hydrochloric acid. The resulting mixture was allowed to stand for 2 days. This yielded 4.06 g (43.8 of crude glyoxal-p-nitrophenylosazone, which, after recrystallization from pyridine, melted at 307-312ยฐC.
We are indebted to the Fonds der Chemie, Farbenfabriken Bayer, and Chemische Fabrik Schering A.G. for generous support for our work.