DE2848151C2 - Process for the hydrolytic degradation of compounds containing ether bonds - Google Patents

Description

It is known that hydriodic acid is often used to split ethers, since the I ion is the is the strongest nucleophilic reagent, which is present in highly acidic solutions that are required for ether cleavage are (cf. e.g. Fieser-Fieser, Organ. Chemie, 1968, pp 359-360). However, the conditions under which hydriodic acid hydrolyzes ether (high Concentration, very high acidity), often for the splitting of ether to clean certain areas or Areas out of the question. For example, you're looking for environmental protection to remove ethers like that out 2,3,7,8-tetrachlorodibenzodioxin (TCDD, »Dioxin«), known from the environmental disaster in Seveso, is unsuitable.

The object of the invention is therefore to provide an effective process for hydrolytic degradation of compounds containing ether bonds, which can be carried out under mild conditions.

This object is achieved by the method described in the claim, which is the subject of Invention represents.

The chloroiodites used according to the invention are soluble in ethanol or methanol, from which they recrystallize are * slightly soluble in water, but can easily be in solutions of the claims defined quaternary ammonium salts are dissolved (e.g. benzalkonium, cetylpyridinium or cetrimide salts), in which the respective chlorine iodide dissolves completely and results in thermodynamically stable solutions. The solutions can release hydriodic acid, which leads to hydrolysis of ether bonds.

According to the invention, the hydrolysis of ether bonds occurs unexpectedly in an aqueous solution of the cationic surface-active compounds according to the claims above the critical micellar Concentration (CMC); this reaction can therefore be regarded as a special type of micellar catalysis will. The importance of the reaction is based on the fact that it is possible with these chloroiodites easily degrade molecules that are insoluble in water, extremely stable and hardly interact with other chemical or physical methods can be degraded. A typical reaction of undoubtedly enormous The breakdown of 2,3,7,8-tetrachlorodibenzodioxin is important. The chloroiodites of the surface-active ones according to the claims quaternary ammonium compounds (of which already have a strong bactericidal effect associated with mild toxicity is known; See. DE-OS 27 39 661) can therefore for environmental protection Cleaning of areas or areas that are used by TCDD or other toxic ethers (such as chlorinated dibenzofurans) are contaminated. The unexpected and unpredictable effect of hydrolysis of ether bonds according to the invention is based on the fact that hydriodic acid, which is derived from chloroiodites is released, under extreme dilution and yet extremely effective. One can do this ascribed to micellar catalysis. The essential characteristic of cationic micellae is in comparison with anionic micellae in that, owing to the positive charge of the nitrogen atom, the same less the Is exposed to the action of counterions; the result is a denser molecular structure and in a higher solubility of non-polar molecules with the same molecular weight, always compared to anionic micellae.

It is also very important in micellar catalysis to know the location of the solubilized molecule that is attached to can reside in different places inside the micellae, e.g. B. deep in the micellae in the radial direction can penetrate or migrate through the micellae, which is near the surface or eventually simply adsorbed on the surface.

It is clear that the acceleration or retardation of organic reactions in the micellar phase is not only by the micella type, but also by the nature of the Solubilization by a particular organic molecule and by its possible distribution between the micellar phase and the aqueous phase can be strongly influenced. In the reactions that the present invention relates to wear the various

Factors favorably contribute to the breakdown of ether molecules by chloroiodite.

According to the invention, the degradation of the ether molecules occurs at room temperature and is not caused by light influenced. It is possible to work in the dark. Preferably used according to the invention Chloride iodites are benzalkonium chloroiodite, cetylpyridinium chloroiodite and cetrimide chloroiodite.

example 1

a) A 0.1 M aqueous solution of cetylpyridinium chloride was prepared; one took 10 ml and added about 50 mg of cetylpyridinium chloroiodite. The solution was until complete Dissolve stirred. The resulting solution was named "Solution A".

b) 5 mg of xanthene were added to 10 ml of a 0.1 M solution of cetylpyridinium chloride and the mixture was stirred until for complete dissolution, being careful

always worked in the dark. Thereafter, the solution A was added and the resulting diluted Solution to 80 ml with distilled water.

Optical density measurements from 240 to 330 nm were then carried out at predetermined time intervals (e.g. 0 h, 30 min, 1 h, 2 h, 3 h, 4 h). A solution with a equivalent concentration of cetylpyridinium chloride and cetylpyridinium chloroiodite compared to that in the solution obtained by dilution described above was used as a comparison

Result: There was a gradual change corresponding to the residence time of xanthene in the chloroiodite solution of the absorption spectrum and a decrease in optical density compared to that characteristic of xanthene Peaks received.

Example 2

5 mg of benzofuran were dissolved with stirring in 10 ml of a 0.1 M solution of cetylpyridinium chloride.

Working with the exclusion of light, 10 ml of solution A according to Example 1 (a) were added. the Measurement of the optical density from 600 to 210 nm was carried out at specified time intervals (e.g. 0 h, 30 min, 1 h, 2 h, 3 h, 4 h). A 0.1 M solution of cetylpyridinium chloride was used, to which one 5 mg / ml of cetylpyridinium chloroiodite had been added as a comparison.

Result: A was obtained corresponding to the residence time of the benzofuran solution with the chloroiodite solution gradual change in absorption spectrum and a decrease in optical density in comparison with the peaks characteristic of benzofuran.

Example 3

5 ml of a 0.1 M solution of cetylpyridinium chloride were added to 20 μg (meg) 2,3,7,8-tetrachlorodibenzo-pdioxin (TCDD) and stirred until completely dissolved. 3 ml of a 0.1 m solution were added to 3 ml of this solution of cetylpyridinium chloride (in which 6 mg / ml of cetylpyridinium chloroiodite had already been dissolved), whereby the solution was always carefully kept in the dark. The blank sample was a 0.1 m solution of Cetylpyridinium chloride containing 6 mg / ml of cetylpyridinium chloroiodite. The optical density was from 400 to 200 nm measured at specified time intervals (e.g. 0 h, 30 min, 1 h, 2 h, 3 h, 4 h, 24 h, 48 h, 72 h).

Result: Corresponding to the time that TCDD remained in the chloroiodite solution, it was absent electromagnetic radiation possible, the gradual decrease in optical density with the absorption peak of TCDD at 290 nm and the subsequent appearance of other peaks around 275 nm that are for some decomposition products of the TCDD (ζ. Ί3. the corresponding 2-phenoxyphenol) typical, known and have been identified by other authors in the photochemical decomposition of TCDD (cf. Fig. 1). Furthermore, portions of this solution became complete with methylene chloride at various times extracted after 7 d and 20 d after storage in the dark. The extracts were used for Evaporated to dryness, dissolved with hexane and fragmented. The rehearsal with a Treatment for 7 days showed 85% degradation of the original TCDD present during degradation 96% reached after 20 days.

Example 4

a) 50 mg of benzalkonium chloroiodite were dissolved in 10 ml of a 0.1 M aqueous solution of

ίο benzalkonium chloride. The solution obtained designated is called "solution B".

b) 5 mg of benzofuran were added to 10 ml of a 0.1-m Solution of benzalkonium chloride and stirred until it was completely dissolved, after which it was added Solution B is excluded from light. The optical density was measured from 600 to 210 nm in given Time intervals (0 h, 30 min, 1 h, 2 h, 3 h, 4 h) using a 0.1 M solution of benzalkonium chloride with 5 mg / ml benzalkonium chloroiodite used as a blank.

The same results as in Example 2 were obtained. Example 5

Was added 5 mg of xanthene to 10 ml of an aqueous 0.1 M solution of benzalkonium chloride and stirred until complete loosening; then 10 ml of Her solution B according to Example 4 a) were added with the exclusion of light. the Measurement of the optical density from 240 to 330 nm was carried out at predetermined time intervals (0 h, 30 min, 1 h, 2 h, 3 h, 4 h). A 0.1 M solution of benzalkonium chloride was used, to which one 5 mg / ml benzalkonium chloroiodite had been added as a blank.

Result: Corresponding to the time that the xanthene solution remained with the benzalkonium chloroiodite solution, there was a gradual change in the absorption spectrum and a decrease in the optical density based on the peaks that are characteristic of xanthene (Fig. 2).

Example 6

a) A 0.1 m solution of cetrimidyl chloride in water was prepared; one took 10 ml and gave about 50 mg Cetrimidchloriodit too. The solution was stirred until completely dissolved (solution C).

b) You gave 5 mg of benzofuran to 10 ml of a 0.1-M solution of cetrimidyl chloride, with one up to complete dissolving stirred. Under constant

In such a way as to exclude light, solution C was added. The measurement of the optical density of 600 was carried out up to 210 nm at specified 2 lead intervals (0 h, 30 min, 1 h, 2 h, 3 h, 4 h). One used one 0.1-M solution of cetrimidyl chloride, to which 5 mg / ml of cetrimidchloroiodite had been added, as Comparative sample.

Result: Corresponding to the time that the benzofuran solution remained with the cetrimide chloroiodite solution, there was a gradual change in the absorption spectrum and a decrease in the optical density based on the peaks characteristic of benzofuran.

For this purpose 2 sheets of drawings

Claims (1)

Claim: Process for the hydrolytic degradation of compounds containing ether bonds, in particular 23,7,8-tetrachlorodibenzo-p-dioxin, by treatment with iodine-containing compounds, thereby characterized in that the ethers are split with an aqueous solution which a) 0.01 to 03 mol / l of a surface-active quaternary ammonium compound of the general formula (1) R ₁ R ₂ R ₃ R ₄ N ⁺ Cl- or Br- (1) and b) 0.01 to 10 g / l of a chloroiodite of a surface-active quaternary ammonium compound of the general formula (II) RiRiR ₃ R ₄ N ⁺ ICI ₂ - (II) contains, where Ri and R _{2 are} Ci -4-alkyl groups,
R3 likewise a Ci _ ₄ alkyl group or a Cio-i8-alkyl group or a benzyl group, R4 is a benzyl group or a 2-benzyloxyethyl group or a 2- [2- (p-l, l, 3,3-tetramethyIbutylphenoxy) ethoxy] ethyl group or where the group RiR ₂ R ₃ N ^{+ means} the pyridinium cation and in this case
R4 is a C10 ie alkyl group.