When the dianil is boiled for some time with concentrated hydrochloric acid, the yellow color of the substance disappears, and the dianil is converted into a colorless substance without, however, passing into solution. The substance so obtained was filtered off, and crystallized from alcohol. It crystallized in small colorless needles, which melted at 183°, and possessed all the properties of the anil, which, in fact, it proved to be. The reaction was therefore
C=N.C₆H₅CO
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/N.C₆H₅ /N.C₆H₅
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C₆H₃—SO₂ + HCl + H₂O = C₆H₃—SO₂ + C₆H₅NH₃Cl
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NO₂NO₂
This reaction also explains the fact that some anil was always obtained in making the dianil from the anilid. Hydrochloric acid is formed in the reaction, and in turn acts on the dianil in the sense of the equation just given.
2. The Action of Alcoholic Potash on the Dianil.
On boiling the dianil with alcoholic potash for a time, the solution turned red, and nothing but tarry products were obtained. In this respect the dianil differs from the dianil of orthosulphobenzoic acid, which under similar conditions, is transformed into infusible anilid. This observation is, however, in keeping with the fact that the nitro derivative, is in general much less stable in the presence of alkali.
3. The Action of Glacial Acetic Acid on the Dianil.
When the dianil is boiled with glacial acetic acid for some time, the color of the solution changes to a much lighter shade of yellow, or becomes colorless. On evaporating the solution to small volume, and allowing it to cool, a colorless substance separates. This is infusible anilid. It could not be obtained in crystals from any solvent, but always separated in flakes. It does not melt or undergo change at 340°.
Like the fusible anilid it dissolves in dilute alkali, but on acidifying the solution it does not immediately reappear. After standing for some time, however, it gradually separates in perfectly pure form. In this particular my observation differs from that of Gray,[27] who states that this anilid is decomposed by solution in alkali.
A specimen that had been repeatedly precipitated gave the following results on analysis.
| I. 0.1607 gram gave 13.88 C.C.N. (standard). | |||
| II. 0.2195 gram gave 0.1285 gram BaSO₄. | |||
| III. 0.1357 gram gave 0.0807 gram BaSO₄. | |||
| C[NH.C₆H₅]₂ /\ /O // Cal. for C₆H₃—SO₂ \ NO₂ | Found. | ||
| I. | II. | III. | |
| N = 10.58 | 10.85 | —— | —— |
| S = 8.06 | —— | 8.00 | 8.16 |