2,2 -Dimethoxypropane

Related Reagents. Benzyl Chloride Benzyl 2,2,2-Trichloroacetimidate Benzyl Trifluoromethanesulfonate p-methoxy benzyl bromide p-methoxy 2,2,2-trichloroacetimidate. 

Greene, X W. Wuts, P. G. M. Protective Groups in Organic Synthesis, 2nd ed. Wiley New York, 1991. 

Handling, Storage, and Precautions flammable liquid irritant. 

The three equilibria shown in eqs 1-3 are established when 2,2-dimethoxypropane, an alcohol, and a catalytic amount of acid are mixed. Distillation of the methanol formed shifts the equilibrium far in the direction of the new acetals. Methanol and 2,2-dimethoxypropane form a binary azeotrope however, this can be broken by the addition of a hydrocarbon solvent such as hexane or benzene. 

Methyl acetals of other ketones can be obtained by acidifying a mixture of the ketone, methanol, and 2,2-dimethoxypropane and removing the acetone formed by distillation. In this case, the function of the 2,2-dimethoxypropane is to react with the water formed to give methanol and acetone (eqs 4 and 5). This is evidenced by the fact that the reaction is very slow in the absence of alcohol or water, but fast when methanol is present. The rate of the reaction is also directly related to the alcohol concentration.  

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The checkers found that commercially available 3-bromo-1,1-dimethoxypropane (Aldrich Chemical Company, Inc.) was unsatisfactory, even after purification, for preparation of the stannane in part B, resulting in greatly diminished yields. 

Furthermore unsaturated aldehydes can be obtained by the reaction of 12 with e. g. cyclohexane carboxylic acid chloride, subsequent alkaline cleavage of the remaining silyl grouping and reduction with sodium borohydride give 3-hydroxy-3-cyclohexyl-1,1-dimethoxypropane (54) which yields 3-cyclohexyl-acrolein (JJ)51 via acid treatment under dehydratation. 

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