DE89244C - - Google Patents

Description

IMPERIAL

PATENT OFFICE.

We have found that smooth nitration of p-amidobenzaldehyde can be achieved if this aldehyde is in the form of easily cleavable substitution products of the general formula

NH ₂ C ₆ H ₄₁ CH: NR,

in which · the aldehyde oxygen is replaced by a divalent radical, the usual one Is subjected to nitration process. Such compounds are primarily the To consider benzylidene compounds from p-amidobenzaldehyde and primary aromatic bases.

In the D. R. P. No. 72173, cl. 22, the benzylidene compounds of benzaldehyde and aromatic monamines have been used to obtain a smooth nitration of the resulting from this combination to a certain extent to achieve tertiary amines. The present procedure, which Starting from amido-substituted benzaldehyde, the aim is not, like that, a nitration of the with the aldehyde connected amine, but rather ι the aldehyde nucleus. While the principle of Method of D. R. P. No. 72173 consists in the fact that the primary one which stands in the way of nitration The amido group of the component to be nitrided must temporarily be tertiary, remains they are primarily used in the present proceedings.

We are in the process of determining the aldehyde group that is disruptive for our purposes the selection of the amines to be used is only limited by the requirements, which the commercial practice places on a technical process from a calculatory point of view.

Example:

19.6 kg of p-amidobenzylideneaniline are dissolved in 200 kg of sulfuric acid of 66 ° B. The temperature can rise to 30 to 40 ⁰ without cleavage of the compound as a result. 50.4 kg of mixed acid of 25 pCt are poured into this solution with good cooling. Enter HNO ₃ , whereby the temperature should not rise above 5 to 6 ° C. if possible. When the nitration is complete, the dark brown solution is stirred into ice water. The new aldehyde separates out in yellow flakes, which are filtered off, washed out, pressed and dried. The yield is quantitative.

The benzylidene compounds of p-amidobenzaldehyde and other primary aromatic bases or nitramines can be used for nitration. Neither is there any change in the result if the sulfuric acid is 66 ° B. through Monohydrate and nitric acid can be replaced by potassium or sodium nitrate.

Following the above procedure, the new nitroamidobenzaldehyde forms a yellow one crystalline powder. He can get through easily

! Crystallization from acetone or alcohol can be obtained in pure form and forms long yellow pegs with a melting point of 170 ⁰ .

The analysis gave figures which correspond to the escape of 1 mol of water from 1 mol. Nitroamidobenzaldehyde speak:

Calculated for
Found ...

NH ₉

C _a H ₃ CHO

N -H. O = ₂ i 8 ₉ 2 per cent.

...... = 18.51 pct.

The nitro-p-amidobenzaldehyde (or his Anhydro compound, as to be assumed according to the above analysis) has the basic properties of ρ-amidobenzaldehyde lost. It is practically insoluble in dilute mineral acids and also in water. The aldehyde is already in the dilute sodium hydroxide solution Cold, completely soluble with weak warming; also takes place complete solution of the Nitro-p-amidobenzaldehyde when heated with sodium bisulfite solution. Diluted mineral acids excrete the aldehyde from the latter solvent after chasing away the sulphurous Acid in crystals again.

Technically important is the ability of the new aldehyde to act with primary, secondary and tertiary aromatic bases to form leuco compounds of the triphenylmethane series. This is how z. B. in the condensation of the aldehyde with Dimetbylanilin a leuco base, which from Benzene-alcohol crystallizes in red-brown needles with a melting point of 202 °; she delivers Lead peroxide oxidizes a green dye, its reduction product a pure blue dye of high technical value

Claims (1)

Patent claim: The process for the preparation of a nitro-amidobenzaldehyde by nitration of the benzylidene compounds of the type NK ₂ C ₆ H ₄ ^ CH: N R.