GB1561334A

GB1561334A - Process for the preparation of alkali-metal phenoxides

Info

Publication number: GB1561334A
Application number: GB5082875A
Authority: GB
Original assignee: Shell Internationale Research Maatschappij BV
Current assignee: Shell Internationale Research Maatschappij BV
Priority date: 1976-12-09
Filing date: 1976-12-09
Publication date: 1980-02-20

Description

(54) PROCESS FOR THE PREPARATION OF ALKALI-METAL PHENOXIDES (71) We, SHELL INTERNATIONALE RESEARCH MAATSHAPPU B.V., a company organised under the laws of The Netherlands, of 30 Carel van Bylandtlaan, The Hague, The Netherlands, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The invention relates to a process for the preparation of a non-aqueous solution of an alkali-metal alkylphenoxide and to a process for the preparation of these phenoxides in the solid state.

Water-free solutions of monocyclic or polycyclic alkali-metal phenoxides can be prepared-according to Netherlands patent application 7 309497by reacting a monocyclic or polycyclic phenol with an alkalimetal hydroxide in the presence of a ketone which is only slightly miscible with water if at all, distilling off the ketone-water azeotrope from the reaction mixture thus formed, separating the ketone from the keton-water azeotrope and recycling the separated ketone to the reaction mixture.

However, the resultant solution of the alkali-metal phenoxide in the ketone still contains dissolved alkali-metal hydroxide.

Boiling down of this solution would therefore result in a residue containing the phenoxide as well as the hydroxide. Consequently, this known process is unsuitable for the preparation of pure solid alkalimetal phenoxides.

In the above-mentioned patent application it is stated that cyclic ethers are solvents for polynuclear alkali-metal phenoxides only. Applicant has found that the alkali-metal salts of phenol itself and monocyclic alkali-metal alkylphenoxides of which the alkyl substituent is located para with respect to the alkali-metal oxy group and monocyclic sodium alkylphenoxides of which the alkyl substituent is located ortho or meta with respect to the alkali-metal oxy group are indeed sparingly soluble in cyclic ethers.

Surprisingly, a number of monocyclic alkali-metal phenoxides have been found to be very soluble in certain cyclic ethers.

The invention relates to a process for the preparation of a non-aqueous solution of an alkali-metal alkylphenoxide, which comprises reacting a monocyclic alkylphenol of which the alkyl substituent(s) is(are) located ortho and/or meta with respect to the hydroxyl group with a hydroxide of an alkali metal having an atomic number in the range of from 19 to 55 inclusive in the presence of a cyclic ether having as sole rings atoms four carbon atoms and two oxygen atoms and dehydrating the solution.

The process according to the present invention usually affords a solution containing the total amount of phenoxide formed.

When the process is modified by replacing the above monocyclic ortho-and/or metaalkylphenol by, for example, pcresol or 4ethylphenol, a precipitate of phenoxide is formed, which, when allowed to settle out from the aqueous and organic phases and filtered off, is contaminated with aqueous solution of alkali-metal hydroxide. The organic phase contains very little dissolved phenoxide, if any.

Examples of cyclic ethers which may suitably be present in the solutions according to the present invention are 1,4-dioxane, 1 ,3-dioxane, 1 A-dioxene, 1 3-dioxene, 1,4dioxine, 2-methyl-1,3-dioxane, 2,5-dimethyl 1A-dioxane, 2-ethoxy-1,3-dioxane, 2,3-dieth oxy- 1 A-dioxane, benzo- 1 3-dioxene, benzo 1 A-dioxene and dibenzo-l,4-dioxine. Preferred cyclic ethers are those in which each of the four ring carbon atoms carries two hydrogen atoms. 1A-Dioxane is particularly preferred as a solvent.

Of the alkali metals having an atomic number in the range of from 19 to 55 inclusive, being potassium, rubidium and cesium, preference is given to potassium.

With respect to the monocyclic alkylphenols preference is given to m-cresol, o-cresol, m-ethylphenol and o-ethylphenol.

The water produced is preferably removed by using a solid dehydrating agent, for example, sodium sulphate, magnesium sulphate, calcium chloride, calcium oxide, barium oxide or a hydroxide of potassium, rubidium or cesium. The alkali-metal hydroxide and the phenol are suitably used in a molar ration in the range of from 1 to 10, particularly from 1 to 2.5. The starting concentration in which the monocyclic alkylphenol is used in the cyclic ether is not critical and may vary within wide limits; it may be, for example, up to 3 mol per litre, The process may be conducted by stirring a solution of the monocyclic alkylphenol in the cyclic ether with more than the stoichiometric amount of a solid hydroxide of potassium, rubidium or cesium, the excess serving as a dehydrating agent.

Thus, the resultant solution of phenolate contains suspended material formed by the uptake of water by the dehydrating agent.

The suspended matter may be removed by filtration or centrifugation.

The process may also be conducted by stirring a solution of the monocyclic alkylphenol in the cyclic ether with a concentrated aqueous solution of potassium hydroxide, rubidium hydroxide or cesium hydroxide. After termination of the reaction the mixture is allowed to separate into an aqueous and an organic layer, after which the organic layer is isolated and dried, for example, with a solid dehydrating agent.

The solutions obtained according to the present invention are particularly suitable for the preparation of dry solid phenolates, which are easy to handle. The invention, therefore, also relates to a process for the preparation of a solid monocyclic alkalimetal alkylphenoxide of which the alkyl substituent(s) is(are) located ortho and/or meta with respect to the alkali-metal oxy group, the alkali metal having an atomic number in the range of from 19 to 55 inclusive, which process comprises boiling down until dryness a solution of the said phenoxide in a cyclic ether having as sole rings atoms four carbon atoms and two oxygen atoms.

Solutions of a monocyclic alkali-metal alkylphenoxide of which the alkyl substituent(s) is(are) located ortho and/or meta with respect to the alkali-metal oxy group, the alkali metal having an atomic number in the range of from 19 to 55 inclusive, in a cyclic ether having as sole ring atoms four carbon atoms and two oxygen atoms, are novel. These novel solutions may also be prepared by dissolving the corresponding monocyclic alkylphenol and react it with an alkali metal having an atomic number in the range of from 19 to 55 inclusive or its amide or hydride in the presence of the cyclic ether.

Potassium m-cresolate can be reacted with chlorobenzene in the presence of cuprous oxide as a catalyst and pyridine as a solvent to give m-phenoxytoluene, a valuable intermediate, particularly in the preparation of pesticides, such as insecticides.

The following examples further illustrate the invention. The dried solutions obtained in the Examples I-VIII were boiled down at a pressure of 15 mm Hg; the residues obtained consisted of potassium m-cresolate and some adhering 1,4-dioxane. The residues were dry powders and could easily be transferred to another vessel. The phenoxides were formed at a temperature of 22"C.

EXAMPLE I A mixture obtained by adding a solution of 93 mmol of m-cresol in 30 ml of 14- dioxane to 800 mmol of potassium hydroxide dissolved in 30 ml of water was stirred for a period of three hours. Then, the suspended potassium hydroxide was removed and the remaining solution dried in the presence of 186 mmol of powdered anhydrous potassium carbonate. Boiling down of the dried solution yielded 14.4 g of a residue.

EXAMPLE 11 The experiment described in Example I was modified in that the remaining solution was dried with powdered anhydrous potassium hydroxide (279 mmol) instead of anhydrous potassium carbonate. Boiling down of the dried solution yielded 13.0 g of a residue.

EXAMPLE 111 A mixture obtained by adding a solution of 93 mmol of m-cresol in 30 ml of 1A-dioxane to 536 mmol of potassium hydroxide dissolved in 20 ml of water was stirred for a period of three hours. Then, the suspended potassium hydroxide was removed and the remaining solution dried in the presence of 900 mmol of powdered anhydrous potassium hydroxide. Boiling down of the dried solution yielded 15.4 g of a residue.

EXAMPLE IV A mixture obtained by adding a solution of 93 mmol of m-cresol in 30 ml of 1A- dioxane to 268 mmol of potassium hydroxide dissolved-in 10 ml of water was stirred for a period of three hours. Then, the suspended potassium hydroxide was removed and the remaining solution dried in the presence of 186 mmol of anhydrous potassium hydroxide. Boiling down of the dried solution yielded 16.3 g of a residue.

EXAMPLE V The experiment described in Example III was modified in that the mixture was stirred for half an hour instead of three hours. Boiling down of the dried solution yielded 1S.1 g of a residue.

EXAMPLE Vl A mixture obtained by adding 179 mmol of potassium hydroxide to a solution of 93 mmol of m-cresol in 30 ml of 1 ,4-dioxane was stirred for a period of three hours.

Then, the suspended potassium hydroxide was removed and the remaining solution boiled down, yielding 14.5 g of a residue.

EXAMPLE VH A mixture obtained by adding 179 mmol of potassium hydroxide and 14 mmol of anhydrous sodium sulphate to a solution of 93 mmol of m-cresol in 30 ml of 1,4dioxane was stirred for a period of two hours. Then, the suspended solid material was removed and the remaining solution boiled down, yielding 15.5 g of a residue.

EXAMPLE VHI A mixture obtained by adding 893 mmol of potassium hydroxide to a solution of 463 mmol of m-cresol in 150 ml of 1,4dioxane was stirred for a period of three hours. Then, the suspended solid potassium hydroxide was removed and the remaining solution boiled down, yielding 70.3 g of a residue.

EXAMPLE IX A mixture obtained by adding a solution of 536 mmol of potassium hydroxide in 20 mol of water to 88 mmol of o-cresol dissolved in 25 ml of 1A-dioxane was stirred for a period of three hours. No precipitate was formed. The mixture was allowed to separate into an aqueous and a dioxane layer. The latter layer contained dissolved potassium o-cresolate.

EXAMPLE X A mixture obtained by adding a solution of 536 mmol of potassium hydroxide in 20 ml of water to 82 mmol of 3-ethylphenol dissolved in 25 ml of 1 A-dioxane was stirred for a period of three hours. No precipitate was formed. The mixture was allowed to separate into an aqueous and a dioxane layer. The latter layer contained dissolved potassium 3-ethylphenoxide.

EXPERIMENT I A mixture obtained by adding a solution of 100 mmol of p-cresol in 25 ml of 1,4dioxane to a solution of 536 mmol of potassium hydroxide in 20 ml of water was stirred. Immediately a white precipitate of potassium 4-methylphenoxide was formed.

EXPERIMENT 2 A mixture obtained by adding a solution of 81.9 mmol of 4-ethylphenol in 25 ml of 1A-dioxane to a solution of 536 mmol of potassium hydroxide in 20 ml of water was stirred. Immediately a white precipitate of potassium 4-ethylphenoxide was formed.

The products obtained in experiments 1 and 2 were allowed to settle out from the aqueous and organic phases. The precipitate collected at the common surface of the two layers. Filtration of the precipitate yielded a filter cake contaminated with the aqueous solution and with 1 A- dioxane.

EXPERIMENT 3 A mixture obtained by adding a solution of 96 mmol of m-cresol in 30 ml of 1,2dimethoxyethane to a solution of 804 mmol of potassium hydroxide in 30 ml of water was stirred for a period of three hours. Then, the etherial layer was isolated by settling and boiled down to yield 17.1 g of a viscous residue.

WHAT WE CLAIM IS: 1. A process for the preparation of a non-aqueous solution of an alkali-metal alkylphenoxide, which comprises reacting a monocyclic alkylphenol of which the alkyl substituent(s) is(are) located ortho and/or meta with respect to the hydroxyl group with a hydroxide of an alkali metal having an atomic number in the range of from 19 to 55 inclusive in the presence of a cyclic ether having as sole ring atoms four carbon atoms and two oxygen atoms and dehydrating the resultant solution.

2. A process as claimed in claim 1, in which each of the four carbon atoms in the ring of the cyclic ether carries two hydrogen atoms.

3. A process as claimed in claim 2, in which the cyclic ether is 1A-dioxane.

4. A process as claimed in any one of the preceding claims, in which the alkylphenol is m-cresol.

5. A process as claimed in any one of claims 1 to 3, in which the alkylphenol is o-cresol.

6. A process as claimed in any one of claims 1 to 3, in which the alkylphenol is m-ethylphenol.

7. A process as claimed in any one of claims 1 to 3, in which the alkylphenol is o-ethylphenol.

8. A process as claimed in any one of the preceding claims, in which the hydroxide is potassium hydroxide.

9. A process as claimed in any one of the preceding claims, in which the solution in the cyclic ether is dehydrated with a solid dehydrating agent.

10. A process as claimed in claim 1, substantially as hereinbefore described with reference to Examples I-XI.

11. Solutions of an alki-metal alkylphenoxide, whenever prepared by a process as claimed in any one of the preceding

Claims

claims.

12. A process for the preparation of a solid monocyclic alkali-metal alkylphenoxide of which the alkyl substituent(s) is(are) located ortho and/or meta with respect to the alkali-metal oxy group, the alkali metal having an atomic number in the range of from 19 to 55 inclusive, which process comprises boiling down until dryness a solution obtained according to a process as claimed in any one of claims 1 to 10.

13. A process as claimed in claim 12, substantially as hereinbefore described with reference to the Examples I-VIII.

14. Solid monocyclic alkali-metal alkylphenoxides of which the alkyl substituent(s) is(are) located ortho and/or meta with respect to the alkali-metal oxy group, whenever obtained by a process as claimed in claim 12 or 13.

15. A solution of a monocyclic alkalimetal alkylphenoxide of which the alkyl substitutent(s) is(are) located ortho and/or meta with respect to the alkali-metal oxy group, the alkali metal having an atomic number in the range of from 19 to 55 inclusive, in a cyclic ether having as sole ring atoms four carbon atoms and two oxygen atoms.