DE91721C - - Google Patents

Description

IMPERIAL

PATENT OFFICE.

The representation of water-soluble azo dyes from safranin and ß-naphtol already forms the Subject of various patents. The combination of diazosafranin with β-naphtol sodium in alkaline solution gives a water-insoluble product. This becomes after the U.S. Patent No. 61692 by treatment with acids a soluble dye obtained. According to the English patent no. 18769 from 1893 the insoluble saffron inazo dye is also soluble in water if it is sufficiently mixed with it Water washes away.

The same success is achieved according to patent no. 85932 by using diazosafranin works on free ß-naphtol in the presence of carbonic acid or organic acids, whereby the water-soluble dye is created directly.

While, according to these known processes, on the one hand, the product of the alkaline Combination of diazosafranin with ß-naphtol further processed, or on the other hand a water-soluble one Safraninazo-ß-naphtol achieved by combining in an organic acidic solution , according to more recent experiments, the same result can be achieved if one uses both Avoid excess alkali as excess acid and exactly 1 mole of hydrochloric acid diazosafranine chloride to 1 mole of β-naphthol sodium based on the reaction equation:

C ₂₀ H ₁₆ N _a (HCl) -NNCl + C ₁₀ H ₇ O Na

= C ₂₀ H ₁₆ N _s (H Cl) NNC ₁₀ H ₆ OH .

In doing so, with the minimum of reagents and operations necessary, one obtains the water-soluble saffron inazo dye in the simplest way in excellent yield.

The process resulted from the consideration that when the safraninazo-β-naphthol is prepared in alkaline solution, the one hydrogen chloride molecule which, according to the latest investigations by Fischer & Hepp, adheres to the imido group of the safranine, is not split off, the safraninazo formed in this way. β - naphtol so the formula applies:

C ₂₀ H ₁₆ N ₃ H (H Cl) N : N- C ₁₀ H ₆ ONa

and when the water-insoluble dye is converted to a dye soluble therein not about the representation of a salt, but about the splitting off of sodium from the hydrochloric acid Azosafranine-ß-naphtol sodium act, either through treatment with acids or by decomposition of the sodium salt, which can be dissociated in water, by continued washing could be done with water.

If the reaction equation above is adhered to Given the circumstances, if the assumption just mentioned was correct, then the formation of a water-soluble Safraninazoss-naphto'l was allowed expect and the experiment actually corresponded to the assumption.

However, analyzes of the water-soluble Safraninazonaphtol dyes are not available, and it would also be a different interpretation of the dye-forming process possible.

According to the English patent No. 18769/93 given ratios, the dye formation proceeds according to the following equation:

ι. C ₂₀ H ₁₆ N _S NH ₂ (HCl) + NaNO, + HCl ^ 2H ₂ O + NaCl + C ₂₀ H ₁₆ N ₃ N ₂ Cl or
C ₂₀ H ₁₅ N ₂ NH (HCl) NN OH,

2. C ₂₀ H ₁₆ N ₃ N ₂ Cl + C ₁₀ H ₇ ONa = NaCl + C ₂₀ H ₁₆ N ₃ N, C ₁₀ H ₆ OH or

.3. C ₂₀ H ₁₅ N ₂ NH (HCl) N ₂ OH + C ₁₀ H ₁ ONa = C ₂₀ H ₁₅ N ₂ NH '(HCl) N-. NC ₁₀ H ₆ ONa.

The process can therefore proceed according to Formula 2 and then it would come from washing out with water from the insoluble Safraninazoss-naphtol, the formula:

C ₂₀ H ₁₆ N ₃ N-. NC ₁₀ H ₆ OH

to, ie the dye would be neither an alkali nor an acid salt, or the process proceeds according to formula 3, whereupon sodium would be split off when washed out with water and the resulting water-soluble safraninazo-ß-naphthol would have the composition C ₂₀ H ₁₅ N ₂ NH (HCl) N: NC ₁₀ H ₆ OH would have to be assigned; the dye in this case would be the hydrochloric acid salt of a dye base. The latter view led to the present proceedings.

English Patent No. 18769/93 does not provide information about the nature of the process remove; The present procedure in particular does not result from this without further ado since the English patent is the cause of the insolubility of the combination of Diazosafranin with ß-naphtol sodium resulting Safraninazo-ß-naphtols the impurities, which are removed by washing to solubilize the same, ascribes while according to the present opinion, the cause of the insolubility in the composition of the dye to look for.

The advantages of the new method over the known ones consist in the fact that Avoiding an excess of alkali and using the calculated amount of acid Operations of patent No. 61692 and English patent No. 18769/93 are saved will. With reference to the method of Patent No. 85932, firstly, precipitation of naphthol with hydrochloric acid from the naphthol sodium solution and, secondly, the addition of Sodium acetate or sodium bicarbonate is avoided, and at the same time, the diazosafranine the naphthol is presented in solution as the sodium salt, which runs as quickly as possible Combination achieved with full utilization of the ß-naphthol and Safranine.

Example: 36.5 kg of tolusafranine are dissolved in approx. 600 liters of water, mixed with 25 kg of ordinary hydrochloric acid (of approx. 30 pCt. HCl ) and diazotized in the cold with 7 kg of nitrite. The diazo solution is then allowed to flow with vigorous stirring to form a cold solution of 16.7 kg of β-naphthol sodium in about 500 liters of water. Instead of adding the diazosafranine to the ß-naphthol solution, the ß-naphthol solution can be poured into the diazo solution with the same success.

The formation of the dye occurs immediately and ends after a few hours. One heats up to boiling, falls with table salt and filtered hot. The dye dissolves easily in water.

Claims (1)

Patent claim: Process for the preparation of water-soluble saffron inazo dyes, consisting therein that one has the same molecules of hydrochloric and sulfuric acids or nitric acid diazosafranine chloride, sulfate or nitrate and ß-naphthol sodium or potassium, avoiding both excess acid and excess alkali allow each other to act. The Safranine used are phenosafranine, Safranin T and Safranin A S.