Water → 5,5-Dimethyl-1,3-cyclohexadiene 3,3-dimethyl-1,4-cyclohexadiene

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Reaction Steps

In a glass flask under nitrogen atmosphere, 50.0 g (0.357 mol) 1,1-dimethyl-3,5-diketocyclohexane was slurried in about 500 mL of diethyl ether. After cooling the slurry in an ice bath, 13 g (0.342 mol) of LiAlH4 was slowly added. The reaction mixture was allowed to warm to room temperature and was stirred for 2 hours, after which 14 g (0.369 mol) of additional LiAlH4 was added. The reaction mixture was refluxed for 2 hours, then stirred overnight. Workup occurred as follows: After the reaction mixture was cooled in an ice bath, 27 mL of water was slowly added, followed by 27 mL of 15 weight percent, aqueous NaOH solution, then 81 mL of water. The resulting solids were filtered off and washed with diethyl ether. The combined ether solutions were concentrated by evaporation. To the resulting pale yellow product was added 10 mL of 9M, aqueous H2SO4. The product was collected after distillation using a short path distillation column up to a pot temperature of 145° C. Additional H2SO4 was added and a second distillation was performed. After washing with 10 weight percent, aqueous Na2CO3, then with water, the product was dried with anhydrous MgSO4. The product was fractionally distilled, with fractions boiling up to about 100° C. being collected. The yield was 12 g. of the isomeric mixture depicted as follows: ##STR5##

Provenance & Evidence