CONTINUOUS METHOD FOR PRODUCING GRIGNARD ADDUCTS AND A DEVICE FOR CARRYING OUT SAME

Abstract

The invention relates to a continuous method for the production of Grignard adducts, in which the magnesium chips are activated mechanically in situ. Furthermore, the invention relates to a device for implementation of the method according to the invention.

Claims

1-14. (canceled)

15. A continuous method for producing a Grignard adduct, wherein a flow consisting of an alkyl- or aryl halide and a water-free solvent and a further flow consisting of magnesium chips are fed to a reactor, and the magnesium chips are activated mechanically in the reactor by friction.

16. The method according to claim 15, wherein the magnesium chips have an average size of 0.5 to 3.0 mm.

17. The method according to claim 15, wherein the mechanical activation is effected by friction of the magnesium chips against each other.

18. The method according to claim 17, wherein the friction is triggered by vibration or grinding movement.

19. The method according to claim 15, wherein the solvent consists of an ether or a mixture of ethers.

20. The method according to claim 19, wherein the ether is diethyl ether, 2-methyl-tetrahydrofuran, tetrahydrofuran, a mixture thereof.

21. The method according to claim 15, wherein the reactor is temperature-controlled at a temperature of 10 to 60 C.

22. The method according to claim 15, wherein the alkyl- or aryl halide is fed to the reactor in a concentration of 0.5 mol/l to 5.0 mol/l.

23. The method according to claim 15, wherein the average dwell time of reagents in the reactor is 1.0 to 20.0 minutes.

24. The method according to claim 15, wherein the magnesium chips are fed such that a molar excess of the magnesium chips is present in the reactor relative to the alkyl- or aryl halide.

25. The method according to claim 24, wherein the molar excess is at least 5-times molar excess.

26. The method according to claim 15, wherein the alkyl- or aryl halide is converted at an output of the reactor up to at least 90% to the Grignard adduct or with an electrophilic educt fed in addition to the reactor, wherein said electrophilic educt is selected from the group consisting of aldehydes, ketones, carboxylic acid esters, thioesters, boronic acid esters, nitriles, imines, epoxides, disulphides, carbon dioxide, further alkyl- or aryl halides or other compounds which comprise active hydrogen or polar double bonds, and mixtures thereof.

27. A device for producing a Grignard adduct comprising a reactor with at least one temperature-control device, at least two supply lines, and an outlet, a device for continuous conveyance of the magnesium chips, a device for mechanical activation of the magnesium chips, at least one magnesium storage container, and at least one pump for conveying the alkyl- or aryl halide.

28. The device according to claim 27, wherein the device for mechanical activation of the magnesium chips consists of a shaker, a vibration- and/or a grinding device and is fitted on or in the reactor or effectively connected to it for introducing the shaking or vibration movement.

29. The device according to claim 27, wherein the reactor has connections and/or viewing windows for analysis devices and/or sensors.

30. The device according to claim 27, wherein the reactor has a cylindrical reaction interior.

31. The device according to claim 27, wherein the reactor is made of a metal.

Description

[0035] The method according to the invention is intended to be explained in more detail with reference to the subsequent example and the appended Figures without wishing to restrict said method to the embodiment which is produced therefrom.

[0036] Test Specification, by Way of Example:

[0037] In a 3D sintered reactor, 15 g of fresh, untreated magnesium chips are introduced. Subsequently, the supply lines and a thermostat are connected to the reactor. Furthermore, a vibration motor is fitted to the reactor. By switching on the vibration motor, the magnesium chips in the interior of the reactor are firstly compacted. The reactor is in addition pre-temperature-controlled to a temperature of 55 C. by the thermostat in order to enable rapid starting of the Grignard adduct formation. Then a water-free solution of phenyl bromide in tetrahydrofuran with a concentration of 1 mol/l is introduced into the reactor. For conveyance of the solution, an injection pump is used and the flow rate is adjusted to 2 ml/min.

[0038] At intervals of a few minutes, inline, infrared spectra are recorded in order to be able to observe the reaction course. Even the first spectrum shows a peak which is attributed to the Grignard compound. The reaction has therefore started immediately. Complete conversion is achieved after 15 min running time.

[0039] During the start-up phase, typically an increase in the temperature is observed. The position of the temperature maximum is thereby dependent upon the filling level with magnesium chips. If the temperature in the start-up phase in the reactor increases above the thermostat temperature, slight boiling of the solvent THF is observed. The thermostat is then adjusted correspondingly to a lower temperature.

[0040] FIG. 1 shows the reaction equation and three IR spectra which were recorded at the beginning of the test, after the start-up phase and after achieving complete conversion.

[0041] By varying the flow rate and the temperature, the process can be optimised. In can be seen in FIG. 2 that, when doubling the flow rate and reducing the temperature to 35 C., incomplete conversion is observed.

[0042] FIG. 3 shows a flow diagram for the method according to the invention and shows which measuring instruments, analysis- or display devices can be used for implementing the method and at which positions these are fitted. In addition, it is shown that the educts are introduced preferably from the bottom into the reactor 4. The alkyl- or aryl halide solution is conveyed through the supply line 1 with the help of a pump. In addition, possibly an electrophilic compound can be conveyed into the reactor 4 via the supply line 2. The magnesium chips are stored in a storage container 5 above the reactor 4. A device for continuous conveyance of the magnesium chips M2 is fitted on the storage container 5, whilst, on the reactor 4, a device for mechanical activation of the magnesium chips M1 is fitted. The Grignard adduct or reaction product is removed from the upper part of the reactor 4 in the line 3. The apparatus is characterised by the fact that the magnesium chips in the reactor chamber drop downwards counter to the flow direction of the solution and form a layer there in which the chips abut against each other and, by a shaking movement, friction between the chips is produced.