6-Acetyl-1,1,2,4,4,7-hexamethyltetralin

The synthesis of 6-Acetyl-1,1,2,4,4,7-hexamethyltetralin (Tonalid) includes the following steps:

1. Cyclization

In a 250 ml three-necked flask fitted with electric stirring, a constant pressure dropping funnel and a thermometer, 40 g of anhydrous AlCl3 and 45 g of dichloromethane were added and mixed with vigorous stirring. A mixture of 90g of p-cymene and 50g of 3,3-dimethyl-1-butene was placed in a dropping funnel, and a cold water bath maintained the temperature in the reaction flask at 15~25C, and the reaction was completed dropwise for 1.5 h. The reaction was continued for 0.5 h. After the reaction, the mixture was poured into iced water, and the oil layer was separated by a separatory funnel, washed to neutrality with a 5% NaOH solution, and H2O, respectively, and dried with anhydrous K2CO3. The organic layer was evaporated out the solvent and by-products under atmospheric pressure, distilled under reduced pressure, collected 100~120C/399.9Pa fractions, and the crude product was recrystallized in isopropanol to obtain colorless crystals of 52.9g with 82.3% yield.

2. Acylation

In a 250m three-necked flask equipped with electric stirring, constant pressure dropping funnel and thermometer, 16g of anhydrous FeCl3 and 43g of 1,2-dichloroethane were added, and stirred to make a thorough mixture. 20g HMT (1,1,2,4,4,7-hexamethyltetralin), 9g acetyl chloride and 22g 1,2-dichloroethane were mixed and stirred until completely dissolved and placed in a constant pressure dropping funnel. The temperature was controlled at 20~25C and the reaction mixture was added dropwise into a three-necked flask. About 45min dropwise addition was completed, the temperature was raised to 40 to continue the reaction for 30min and then it was immediately poured into ice water to separate the oil layer, washed with 5% NaOH solution and water to neutral, dried with anhydrous KCO, and 79g of reddish-brown liquid was obtained. It was evaporated out of the solvent at atmospheric pressure, distilled under reduced pressure, collected 130~150 /26.66Pa fraction, cooled to get 6-Acetyl-1,1,2,4,4,7-hexamethyltetralin (Tonalid) as white crystals 19.5g, yield 81.4%.