DE1118771B - Process for the recovery of chlorine and bromine in the form of highly volatile alkyl halides from the residues resulting from the reaction of alkyl aluminum halides with silicon or boron compounds - Google Patents

Description

Process for the recovery of chlorine and bromine in the form of volatile Alkyl halides from the in the reaction of alkyl aluminum halides with silicon or. Boron Compound Residues A number of reactions have been proposed where alkyl aluminum halides are used to alkylate various materials be used.

One such method has been proposed to use organosilanes by reacting an organic aluminum halide with a silicon dioxide or Manufacture of silicate. In this case, the alkyl aluminum halide can either be previously or prepared on site by the reaction of an alkyl halide with Aluminum can be formed.

In another process, organic boron compounds are made by the conversion of organic aluminum halides with various boron-containing Compounds such as boron oxide and metal borates are produced. In all implementations of this type, the main by-product is a residue, which is aluminum in conjunction with a halogen contains. This by-product has to be processed further little value. In addition, the economy of processes of this type would be increased will, if it were possible, at least part of this residue in one to regain technically usable form.

According to the invention by a method for the recovery of Chlorine and bromine in the form of volatile alkyl halides from the reaction residues arising from alkyl aluminum halides with silicon or boron compounds achieved in such a way that the residues mentioned at 120 to 4000 C with a Compound of the formula ROR ', in which R is a methyl or ethyl group and R' is a methyl or ethyl group or hydrogen, while distilling off the formed volatile alkyl chloride or bromide are implemented.

Reactions in which such a residue is obtained are, for example the preparation of silanes by reacting an alkyl aluminum halide of the formula Ru Al X3 ,, where R is a methyl or ethyl group, X is chlorine or bromine and a 1 or 2 is, with silicon dioxide or a silicate, the production of boranes by Reaction of an alkyl aluminum halide and a boron compound, such as boron oxide or a borate.

The process according to the invention can be carried out within a wide temperature range from 120 to 4000 C. Preferably, however, at temperatures worked in the range from 200 to 3000 C.

Suitable compounds for reaction with the residue according to the invention Processes are methanol, methanol, dimethyl ether, diethyl ether and methyl ethyl ether. Preferably, however, methanol is used when a methyl halide and diethyl ether used when an ethyl halide is to be produced.

The reaction is usually carried out by using the steam passing the compound of formula ROR 'through the residue in a suitable manner. So the residue can be in the form of a column and the vapor can be passed through will. Instead, the residue can be fed continuously into a bed, in which by the steam passing through the compound RO R 'in the form of a Fluidized bed is maintained. In this case, the process can be carried out continuously will. According to a further embodiment, the reaction can be carried out under pressure in one Pressure reaction vessel can be carried out. According to a further procedure, the Reactants after mixing in a suitable vessel, for example one heated kettle to be heated together.

According to the method according to the invention, at least one main part of the halogen contained in the residue in a technically valuable and usable one Shape, d. H. as the alkyl halide.

The invention is illustrated by the following examples in which the parts and percentages are by weight.

Example 1 303.5 parts of methyl aluminum sesquichloride and 203 parts Acid-treated bauxitic clay were put together at an elevated temperature implemented to produce volatile methylsilanes. You also got one solid powdery residue containing approximately 330/0 chlorine. This residue was heated to 3,100 ° C with rubbing in a reaction vessel, and 144 parts Methanol vapor was bubbled through for 6 hours with stirring. During this In time, 145 parts of methyl chloride containing approximately 10 parts were distilled Hydrogen chloride and were collected.

Example 2 92 parts of methyl aluminum sesquichloride and 85 parts of acid treated Bauxitic clay were used together at elevated temperatures to produce volatile Methylsilanes implemented. A powdery residue was also obtained, which Contained 25 0 / o chlorine. This residue was placed in a reaction vessel with stirring heated, and 36 parts of methanol vapor were released at a rate of 12 parts passed per hour. During this time 37 parts of methyl chloride distilled and 3.5 parts of hydrogen chloride, which were collected.

Example 3 30 parts of a powdery residue with 104% chlorine content were made by reacting an acid-treated bauxitic clay with methylaluminum sesquichloride obtain. This material was heated to 2800 ° C. and the residue was washed off 3 parts of dimethyl ether passed with stirring.

1.0 part of methyl chloride and 1.1 parts of unreacted ether distilled off and were collected.

Example 4 327 parts of ethyl aluminum sesquibromide, 114.5 parts of anhydrous Aluminum chloride and 30 parts of boron oxide were heated together to add boron triethyl to win. 28 parts of diethyl ether were for 1 hour to 50 parts of the after given residue obtained above procedure. The mixture was sent to distillation in a and condensing the distillate in a vessel set up for 2 hours at atmospheric Pressure heated to 1200 C and the temperature in the course of a further hour 2000 C increased. 25 parts of ethyl bromide and 6 parts of ethyl chloride distilled off and were collected.

Example 5 670 parts of ethyl aluminum sesquibromide and 200 parts of bentonite were together at an elevated temperature temperature converted to volatile ethylsilanes to win. A residue was obtained from this process which contained 51.84 bromine contained. 40 parts of this residue were placed in a reaction vessel with stirring heated to 2150 C and 8 parts of methanol, mixed with nitrogen, passed through. 14.8 parts of a product were obtained which distilled over at 85.degree the analysis was methyl bromide.

Example 6 40 parts of the residue used in Example 5 became similarly using 9.2 parts diethyl ether in place of the methanol treated. A liquid containing 7.9 parts of ethyl bromide, 0.2 parts of methyl bromide and contained 3.4 parts of unreacted ether, distilled off and was collected.

Example 7 160 parts of acid-treated bauxitic clay and 90 parts Aluminum (aluminum content 910/0) were reacted together at elevated temperatures, by passing through 310 parts of methyl chloride for 10 hours to avoid volatile Generate methylsilanes. This process gave 430 parts of a 500/0 Residue containing chlorine. The residue was heated to 2700 C, and during 200 parts of methanol were passed through for 5 hours with stirring. During the first Nitrogen was also added along with the methanol at one rate for 3 hours passed through at 6 parts per hour. 190 parts of a liquid distilled off and were collected.

This liquid consisted of 164 parts of methyl chloride, 10 parts Methanol and 16 parts of hydrogen chloride.

Claims (4)

PATENT CLAIMS: 1. Process for the recovery of chlorine and bromine in the form of volatile alkyl halides from the reaction of alkyl aluminum halides with silicon resp. Residues arising from boron compounds, characterized that said residues at 120 to 4000 C with a compound of the formula ROR ', where R is a methyl or ethyl group and R' is a methyl or ethyl group or hydrogen, with distilling off the readily volatile Alkyl chloride or bromide are implemented. 2. The method according to claim 1, characterized in that the temperature is kept in the range of 200 to 3000 C. 3. The method according to any one of the preceding claims, characterized in, that the residue is in the form of a column and the compound of the formula ROR ' is passed through in vapor form. 4. The method according to any one of claims 1 to 3, characterized in that that the residue fed to a fluidized bed and the compound ROR 'as the the Fluidized bed maintaining medium is passed through.