DE154655C - - Google Patents

Description

¹ ί γ b-'C-Z nt bet a ι ie '.'....

IMPERIAL

PATENT OFFICE.

It is known that toluene-sulfamide, both the ortho- as the para- \ ⁷ Getting Connected dissolves in Ätzkalien to form salts, in which a hydrogen atom of the amide group replaced by metal. For example, the sodium salt has the composition:

'NH-Na.

",,.

It is also known that these salts are replaced by the weakest acids, even carbonic acid, are decomposed with the separation of free toluenesulfamide, which is sparingly soluble in water.

Are made from a mixture of o- and

Γ H / 3 -I- Mn HPl

^{Ua £ li} \ S0 ₃ .NH'Na r * a. ₂ no

however, the toluenesulfamide salt solution remains unchanged upon addition of the solution normal salt (sodium sulphate, potassium chloride, potash nitric acid, etc.).

Also soluble salts of the alkaline earths (calcium chloride, chlorobaryum, barite nitrate, etc.) remain without effect on a solution of the alkali salts of toluene sulfamide (the same, whether o- or p-toluenesulfamide).

The ammonium salts are an exception to the behavior of normal salts of alkalis and alkaline earths against toluene sulfamide salt solutions. When normal ammonium salts are added, the reaction proceeds in such a way that the toluenesulfamide alkali salts are fractionated with the deposition of toluenesulfamide p-toluenesulfamide salt, the free toluenesulfamides are separated out by the gradual addition of acid and the individual fractions are separated, so that the first precipitation products are found richer are in o-, the last rich in p-toluene-sulfamide, such that can be effected in this way, a separation of the mixture of o- and ρ-toluene-sulfamide into its component parts (see FIG. Pat 76,881th ^12).

Just as with free acids, acid salts can be used from the solutions of the toluene sulfamide salts free toluenesulfamide are deposited, even if these salts, e.g. B. disodium phosphate, borax, sodium bicarbonate, react alkaline:

= C ₆

_ + Na, PO ,;

and free ammonia are decomposed, for example when using ammonium chloride according to the following equation:

NH-Na

+ NH ₁ -Cl =

NH, + NaCl.

SO ₂ -NH ^

The toluenesulfamide falls when its alkali salt solution is mixed with that of one Ammonium salt immediately.

The above-described reaction of toluenesulfamide salts with normal ammonium salts, in which free toluenesulfamide is deposited with elimination of ammonia, was not previously known; she can benefit

can be used to clean toluenesulfamide. To this end, will impure toluenesulfamide dissolved in alkali and the solution filtered and washed with an ammonium salt solution added in excess, so that all of the toluenesulfamide is free of impurities, can be obtained in particular from coloring admixtures.

The investigation has also shown that

ίο the precipitation of toluenesulfamide salt solutions by means of ammonium salts as well as the above-mentioned decomposition of the amide salts by acids, for the separation of a mixture of o- and p-toluenesulfamide into its components can be used.

The application of ammonium salts for this

offers compared to the aforementioned trend

- tion of the amides by acids or by acid salts technical advantages. Namely, as is almost always the case, the toluenesulfamides by treatment with toluenesulfochloride produced with ammonia, one obtains according to the equation:

a mixture of toluenesulfamide and chlorammonium, from which the latter means Water is leached. At the same time, some amide goes with the chlorammonium in solution, the separation of which from the ammonium chloride is difficult to effect and that for the further process of obtaining sweetener (from o-toluenesulfamide) must be considered lost. The toluenesulfamide dissolved in the chlorammonium liquor however, it can be made usable if the filtered liquor is fractionated Precipitation of o- and p-toluenesulfamide used as described above, which seems all the more possible, as the impurities of the raw amide (im essential ditolyl sulfone) do not pass into the chlorammonium solution, and the latter accordingly is obtained in fair purity. The separation itself happens through fractional Precipitation, the first deposits being richer in o-, the last being richer in p-compounds.

To ensure a complete separation of o- and p-toluenesulfamide in regular operations reach, one first precipitates most of the o-amide, which one by filtration or centrifugation separates the liquor. The latter becomes through a further addition a mixture of o- · and p-toluenesulfamide excreted from ammonia salt, which in returned to operation and then together with the next portions of raw amide is subjected to re-treatment with ammonium salts. From the above Amide mixture (the so-called middle fraction) can be filtered off final liquor thereupon by means of ammonia salt or by means of Acid precipitate the remaining p-toluenesulfamide.

Example:

200 kg of toluenesulfamide mixture, containing about 130 kg of o-amide and 70 kg of p-amide, are dissolved in 235 1 of sodium hydroxide solution of 23 ^° Be. (with a content of 200 g Na OH per 11 lye) and mixed with 35 kg chlorammonium (dissolved in 80 to 90 1 water). The resulting precipitate of o-toluenesulfamide (iiokg, dry) is filtered off and the filtrate is mixed with a further 10 kg of chlorammonium, whereby the remainder of the o- and part of the p-toluenesulfamide is precipitated. The precipitate goes back to the factory and is processed further together with the next portion of raw amide. The remainder of the p-toluenesulfamide can be precipitated from the liquor in the manner described.

The technical progress associated with the present process also results from the fact that the separation of o- and p-toluenesulfamide when using acid to decompose their salts is far less perfect than when using ammonium salts. The amides are precipitated so suddenly when using concentrated hydrochloric acid, for example, that the decomposition reaction remains local even when strong stirrers are used and the first fractions already have a high toluenesulfamide content. In order to remedy this inconvenience to some extent, one is forced to strongly dilute the precipitating ^{acid (down to 5 to 7 0} Be.), A circumstance which favors further losses of toluenesulfamide. On the other hand, the reaction with ammonium salts takes place more slowly and enables almost all of the o-toluenesulfamide to be obtained in a pure state during the first precipitation. The reason for the different behavior of the acids in contrast to the ammonium salts is easy to see. When using the latter, an (unstable) ammonium salt is initially formed, which gradually decomposes under the influence of the concentration ratios, stirring, etc. in the manner indicated above, thereby promoting complete separation of the o- and p-compounds according to their different solubilities.

The yields were as follows: 370 kg each of crude amide (obtained by amidation of 400 kg of liquid toluenesulfochloride mixture) were dissolved in 300 kg of caustic soda of 3 8 ° Be. The solution was added:

Experiment I with hydrochloric acid of about 6 ° Be. Yield: 1st fraction, centrifuged and covered: 240 kg of o-toluenesulfamide.

Experiment II with chlorammonium waste liquor. Yield: 1st fraction, centrifuged and covered: 260 kg o-toluenesulfamide.

In every attempt the first fraction was precipitated until it appeared of p-toluenesulfamide (controlled by observation under the microscope). The capping of the precipitate was done using the same for each experiment Amount of water causes.

It should be noted by the way that this is the case with the use of chlorammonium waste liquor according to the equation:

NH- Na

NH ₁ . Cl =

NH ₂

^NaCl

escaping ammonia can be recovered with ease and almost free of charge, provided that the precipitation is carried out in closed apparatus.

Claims (1)

Patent claim: Process for the purification and separation of o- and p-toluenesulfamide. through this characterized in that one for the complete or fractional precipitation of the caustic alkaline Solution of sulfamides uses normal ammonium salts.