Nitrobenzaldehyde Dimethylacetal

B. m-Nitrobenzaldehyde dimethylacetal. The above crude product is dissolved in 750 ml. of technical anhydrous methanol, 1 ml. of concentrated hydrochloric acid is added if necessary (Note 6), and the solution is allowed to stand at room temperature for 5 days (Note 7). A solution of sodium methoxide in methanol is added until the solution is just alkaline to moistened litmus paper. The methanol is removed by distillation on a steam bath the residue is cooled to room temperature and treated with cool water to dissolve the inorganic salts. The aqueous solution is extracted with two 50-ml. portions of ether, and the extracts are added to the crude acetal. The solution is subjected to a preliminary drying over anhydrous magnesium sulfate (or sodium sulfate), filtered, and then dried for at least 12 hours over anhydrous sodium carbonate. After the ether has been removed by distillation on a steam bath the residue is distilled under reduced pressure from a 500-ml. Claisen flask. The yield of the light yellow liquid acetal, boiling at 141-143V8 mm. (Note 8), is 300-335 g. (76-85%) (Note 9). 

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