Reaction LXXXVII.—Hydrolysis of certain Anils

Reaction LXXXVII. Hydrolysis of certain Anils. (B., 35, 1228 D.R.P., 121745.)—When derivatives of toluene which contain negative groups in the o- and p-positions are treated with p-nitrosodimethyl- 

These anils are readily hydrolysed by acids to yield derivatives of benzaldehyde. 

50 gms. (1 mol.) of 2 4-dinitrotoluene, 50 gms. (excess) of p-nitroso dimethylaniline and 90 gms. of crystallised sodium carbonate are refluxed on a water bath for 6 hours with 300 c.cs. of alcohol. The anil which separates is filtered off, washed with boiling water, and recrystallised from acetone. The whole is then mechanically shaken for 4 hours with 350 gms. (excess) of nitric acid (D. 1-17) and 300 c.cs. of benzene, filtered, the benzene layer separated and the solvent removed on a water bath. The residue is recrystallised from alcohol, with the addition of animal charcoal, being precipitated from the alcoholic solution by dilution with water. The crystals which separate contain 1 mol. of alcohol of crystallisation this they lose at 90°. The aqueous layer above is re-shaken with benzene and nitric acid, and worked up for further aldehyde as above. 

Reaction LXXXVm. Action of Nitrous Acid on the Monoximes of a-Diketones. (A., 274, 71.)—When compounds containing the group —CH2—CO—are treated with nitrous acid in presence of sodium, an iso-nitroso compound identical with the monoxime of the corresponding oc-diketone is obtained (see p. 111). From the monoxime by the further action of nitrous acid in the presence of glacial acetic acid, the diketone itself is formed. 

It may be noted that aldehydes and ketones can usually be obtained from the corresponding oximes, phenyl-hydrazones, semi-carbazones, etc., by hydrolysis with dilute mineral acids. 

---