Propylene Glycol → 1,3-Dioxolane, 2,4-dimethyl-2-(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthalenyl)-

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Reaction Steps

Acetyl chloride (0.15 g) is added dropwise at room temperature to a mixture of 52.5 g (0.35 mol) of ethyl orthoformate, 30 g (0.13 mol) of 6-acetyl-1,1,4,4-tetra-methyl-tetralin and 18 ml of ethanol. The reaction is slightly exothermic, which results in a temperature increase from 20° C. to 28° C. The mixture is stirred at this temperature for 2 hours. The excess ethyl orthoformate and ethanol are removed by vacuum distillation (120° C./ 100 mm Hg). After this time the reaction mixture is cooled and 50 ml of toluene, 22.5 g (0.29 mol) of propylene glycol and 0.3 g of p-toluenesulphonic acid are added rapidly. The mixture is stirred at 85° C. to 90° C. for 2 1/2 hours. The ethanol which is formed is removed by distillation. Thereupon, the residual mixture is neutralized by the addition of a 10% solution of potassium hydroxide in ethanol, filtered and the filtrate is evaporated. Crude 2-dimethyl-2-(1,1,4,4-tetramethyl-tetralin-6-yl)-1,3-dioxolane is obtained. The product is purified by vacuum distillation and there are obtained 23.7 g of pure product. The boiling point of the pure product is 112° C. at 0.45 mmHg.

Provenance & Evidence