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15.6 g (0.65 mol) of magnesium and 20 ml of THF were placed in a 1-liter reaction flask in a stream of nitrogen, the reaction was initiated with a small amount of ethyl iodide and iodine, and a solution of 111.15 g (0.65 mol) of p-bromotoluene in 500 ml of THF was added dropwise at a temperature from room temperature to 40° C. for 2 hours to prepare a Grignard reagent. A solution of 83.75 g (0.625 mol) of p-methylacetophenone (11c) in 200 ml of THF was added dropwise thereto at the same temperature for 3 hours. The resulting solution was stirred at room temperature for 3 hours, and subsequently stirred under reflux for 4 hours. Then, the solution was cooled, and poured into 1 liter of 5% aqueous sulfuric acid to conduct hydrolysis. The resulting product was extracted with toluene, and the extract was washed with aqueous soda ash, washed with water, and concentrated. Then, 300 ml of toluene and 0.5 g of PTSA were added thereto, followed by stirring under reflux for 4 hours to carry out azeotropic dehydration. The resulting product was washed with aqueous soda ash, washed with water, and concentrated. Crude 1,1-di(p-tolyl)ethylene (9c) was distilled in a Claisen flask equipped with a vigreux to obtain 98.5 g.

1. stirringsubsequently stirred
2. temperatureunder reflux for 4 hours
3. temperatureThen, the solution was cooled
4. customhydrolysis
5. extractionThe resulting product was extracted with toluene
6. washthe extract was washed with aqueous soda ash
7. washwashed with water
8. concentrationconcentrated
9. additionThen, 300 ml of toluene and 0.5 g of PTSA were added
10. stirringby stirring
11. temperatureunder reflux for 4 hours
12. washThe resulting product was washed with aqueous soda ash
13. washwashed with water
14. concentrationconcentrated
15. distillationCrude 1,1-di(p-tolyl)ethylene (9c) was distilled in a Claisen flask
16. customequipped with a vigreux
17. customto obtain 98.5 g