NL7908995A - PROCESS FOR PREPARING BETA-FLUOROALKYL CARBONATES. - Google Patents

Description

S 2348-994 ί P & C Λ.

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Process for the preparation of β-fluoroalkyl carbonates.

The invention relates to a process for preparing β-fluoroalkyl carbonates.

The synthesis of bis (2,2,2-trifluoroethyl) carbonate by reacting β-trifluoroethanol with phosgene is described in an article by Aldrich 5 and Shepard, J. Org. Chem. 29, 11 (1964).

The invention provides a process according to which a β-fluoroalkanol is reacted under anhydrous conditions with carbon monoxide in the presence of a palladium compound, oxygen and a manganese-containing redox cocatalyst, to form a β-fluoroalkyl carbonate.

The reactants and the reaction products obtained from the present process can be illustrated by the following equation, given by way of example only, since the reactants, the reaction products and the reaction mechanisms of the preparation of β-fluoroaliphatic carbonates are different and / or be more complex: kst 15 2CF3CH2OH 4 CO + 1/2 02 -> (CF ^ O) 2 ~ C0 + H20.

The β-fluoroalkanol used as a reactant can contain 2-10 carbon atoms; preferably this compound contains 2-4 carbon atoms. Examples of these β-fluoroalkanols are CH2FCH2OH, CHF2CH2OH, CF ^ C ^ OH, (CF3) 2CHOH, CF3CF2CH2OH, CF3C (CH3) H-OH and CF3CF2CF2CH2OH.

The palladium compound can be an inorganic or organic compound or a complex. For example, the palladium can be used in the form of oxide, halide, nitrate, sulfate, oxalate, acetate, carbonate, propionate, hydroxide or tartrate. Examples of palladium complexes are those with carbon monoxide, nitriles, tertiary amines, phosphines, arsenics and stibienes.

Specific examples of palladium compounds and complexes are:

PdCl2, PdBr2, Pal2, [Pd (C0) Cl2] 2, [Pd (CO) Br2] 2, [Pd (CO) I2J2, (CgHgCN) 2PdCl2, PdCl4, Pd (OH) 2 (CNC4Hg) 2, PdI2 ( CNCgH5) 2, Pd (OH) 2 (CNC ^ OCgHg) 2, Pd (CNC4H9) 4,

Pd (CO) Cl, Pd (CO) Br, Pd (CO) I, PdH (C0) Cl, PdH (C0) Br, Pd (CgHg) (H20) Cl04,

Pd2 (CO2 Cl, [(HgC4) 4N] 2PdBr4, K2Pd2 (CO) 2C14 and Na2Pd2 (CO) 2Br4-30 Oxygen is used as the sole oxidizing agent in combination with a redox cocatalyst selected from manganese chelates. Examples of manganese containing redox- cocatalysts are manganese chelates containing ligands selected from--hydroxyoximes, ortho-hydroxyarene oximes, α-diketones or β-diketones, including combinations thereof Examples of known commercially available redox cocatalysts are manganese (II ) bis (acetylacetonate), manganese (II) bis (benzoin oxime), etc. The redox cocatalysts are known materials and can be readily prepared, for example, as described in U.S. Pat. Nos. 7908995.

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Ί * - 2 - 3,972,851, 3,965,069, 3,956,242, 3,781,382, 3,455,880 and 3,444,133.

The present process can be carried out in the absence of a solvent, for example when the β-fluoroalkanol functions both as a solvent and as a reactant. Representative examples of solvents that can be used are: dichloromethane, dichloroethane, chloroform, carbon tetrachloride, tetrachlorethylene, nitromethane, hexane, 3-methylpentane, heptane, cyclohexane, methylcyclohexane, cyclohexane, isooctane, p.cymene, decane toluene, benzene, diphenyl ether, dioxane, thiophene, dimethyl sulfide, ethyl acetate, tetrahydrofuran, chlorobenzene, anisole, bromobenzene, o.dichlorobenzene, methyl formate, iodobenzene, acetone, aceto-phenone, etc., and mixtures thereof.

Although not necessary, the process can be carried out under basic reaction conditions. Representative examples of basic materials that can be used are: alkali metals and alkaline earth metals in elemental form; basic quaternary ammonium compounds, quaternary phosphonium compounds and tertiary sulfonium compounds; alkali metal and alkaline earth metal hydroxide; salts of strong bases and weak organic acids; primary, secondary and tertiary amines; etc. Specific examples of the above materials are metallic sodium, potassium, magnesium, etc .; quaternary ammonium hydroxide, tetraethyl phosphonium hydroxide, etc .; sodium, potassium, lithium and calcium hydroxide; quaternary phosphonium carbonates, tertiary sulfonium carbonates, sodium, lithium and barium carbonate, sodium acetate, sodium benzoate, sodium methylate, sodium thiosulfate; sodium compounds such as sodium sulfide, tetra-25 sulfide, cyanide, hydride and borohydride; potassium fluoride; methylamine, isopropylamine, methylethylamine, allylethylamine, di-tert-butylamine, dicyclohexylamine, dibenzylamine, tert-butylamine, allyldiethylamine, benzyldimethylamine, diacetyl-chloroethyl-dimethyl-phenylamine, l-ethyl-ethyl-propyl-amine , N'-dimethylethylenediamine, N, N, N'-tri-tert-butylpropane-diamine, N, N ', N', N "-tetramethyl-diethylenetriamine, pyridine, aminomethylpyridines, pyrrole, pyrrolidine, piperidine, 1,2, 2,6,6-pentamethylpiperidine and imidazole Particularly preferred bases are lithium, sodium, potassium, calcium and barium hydroxide, sodium, lithium and barium carbonate, sodium acetate, sodium benzoate and sodium methylate, including mixtures of these.

Although not necessary, the process may be carried out in the presence of an organic phase transfer agent, for example, any onium compound suitable as a phase transfer agent, such as quaternary ammonium hydroxide and tetraethylphosphonium hydroxide 7908995 *. Starks, N. A.C.A. 93, 195 (1971)]; "crown" ethers suitable as phase transfer agents [Aldrichimica Acta 9, Issue Nr. 1 (1976) "Crown Ether Chemistry; Principles and Applications" by G.W. Gokel and H.D. Durst, and U.S. Patent 3,622,577]; cationic chelate salts, for example, alkali metal and alkaline earth metal diamine halides; and cryptates.

The molar ratio between palladium and β-fluoroalkanol is 0.001: 1 -1000: 1 and preferably 0.1: 1 - 10: 1.

When using a base, an effective molar ratio between base and palladium is 0.000001: 1 - 100: 1; preferably this ratio is from 0.5: 1 to about 10: 1 and even more preferably from 1: 1 to 2: 1.

The molar ratio between oxidant and β-fluoroalkanol can be in the range of 0.001: 1 - 1000: 1; preferably this ratio is 0.1: 1 - 10: 1.

The molar ratio between the redox catalyst and β-fluoroalkanol is 0.0001: 1 - 1000: 1, preferably 0.0001: 1 - 1: 1 and even more preferably 0.001: 1 - 0.01: 1.

The molar ratio between phase transfer agent and palladium can be 0.00001: 1 - 1000: 1; preferably this ratio is 0.05: 1 - 100: 1 and even more preferably 10: 1 - 20: 1.

The present process is preferably conducted under positive carbon monoxide pressure sufficient to form the desired β-fluoroaliphatic carbonate, generally about 0.5-500 atmospheres, and preferably 1-200 atmospheres.

25 In general, the optimum reaction temperature is 0 ° - 200®C; the reaction temperature is preferably 0 ° - 50 ° C.

In the examples below, all reaction products were verified by gas chromatography and mass spectrometry.

EXAMPLE I

To a 50 ml three-necked flask fitted with inlets to introduce air and CO below the surface, 1.0 g (10.0 mmol) of CF 1 CH 2 OH (2,2,2-trifluoroethanol), 0.027 was charged g (0.1 mmol) PdB ^, 0.106 g (0.3 mmol) MntacacJ ^ manganese trisCacetylacetonate)), 0.23 g (1.5 mmol) 1,2,2,6,6-penta-methylpiperidine, 2 g of molecular sieves Linde 3A and 25 ml of dichloromethane.

100.0 µl of toluene was used as the internal standard and bubbled through the mixture at 25 ° C and air for 16 hours. Vapor phase chromatography revealed the presence of 0.74 g (conversion 67%) of bis (2,2,2-trifluoroethyl) carbonate of the formula (CF ^ CH2 O) ^ - CO.

7908885

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EXAMPLE II

Into a 50 ml three-necked flask equipped with inlets to introduce air and CO below the surface, 32.2 g (0.322 mmol) of CF 1 Cl 2 OH, 0.027 g (0.1 mmol) PdB 2 0.106 g (0.3 mmol) Mniacac) ⁄ / 0.232 g 5 (1.5 mmol) 1,2,2,6,6-pentamethylpiperidine and 2 g molecular sieves

Linde 3A. CO and air were bubbled through the mixture for 16 hours. Vapor phase chromatography revealed the presence of 0.44 g of bis (2,2,2-trifluoroethyl) carbonate.

EXAMPLE III

In a 100 ml three-necked flask equipped with inlets to introduce air and CO below the surface, 3.8 g (38 mmol) CF ^ C ^ OH, 0.027 g (0.1 mmol) PdB ^ 0.106 g (0.3 mmol) Mniacac) / 2 g molecular sieves Linde 3a and 50 ml dichloromethane. CO and air were bubbled through the mixture for 42 hours. Vapor phase chromatography revealed the presence of 0.26 g of bis (2,2,2-trifluoroethyl) carbonate.

EXAMPLE IV

Into a 100 ml three-necked flask equipped with a CO inlet and an air inlet, an outlet tube and a magnetic stir bar, 1.28 g (12.8 mmol) of CF ^ C ^ OH, 0.104 g (1.3 mmol) 50% aqueous lye (NaOH), 0.37 g (1.6 mmol) tetrabutyl ammonium bromide (Bu / N Br), 2.0 g molecular sieves and 70 ml dichloromethane. The mixture was stirred at room temperature for 1 hour, after which 0.076 g (0.3 mmol) Mn (acac) ^ and 0.027 g (0.1 mmol) PdB ^ were added. CO and air were bubbled through the mixture for an additional 18 hours at room temperature. Vapor phase chromatography showed the presence of 0.94 g (conversion 73%) bis (2,2,2-trifluoroethyl) carbonate.

EXAMPLE V

Into a 100 ml three-necked flask equipped with a CO inlet, air inlet, outlet tube and magnetic stir bar, 40 ml of CF 2 CH 2 OH, 0.104 g (1.3 mmol) of 50% aqueous caustic solution and 3 ml. 0 g molecular sieves. The mixture was stirred at room temperature for 1 hour, after which 0.027 g (0.1 mmol) of PdB 2 and 0.076 g (0.3 mmol) of Mnfacac 2 were added. CO and air were slowly bubbled through the reaction mixture for an additional 18 hours. Vapor phase chromatography revealed the presence of 8.45 g (conversion 16.4%) of bis (trifluoroethyl) carbonate.

7908995

Claims (9)

1. Process for preparing β-fluoroalkyl carbonates, characterized in that a β-fluoroalkanol is reacted under anhydrous conditions with carbon monoxide in the presence of palladium, oxygen and a manganese-containing redox cocatalyst. 2. Process according to claim 1, characterized in that the conversion is carried out in the presence of a base. Process according to claim 1 or 2, characterized in that the conversion is carried out in the presence of a phase transfer agent. 4. Process according to claims 1-3, characterized in that the conversion is carried out in the presence of a drying agent. Process according to claim 4, characterized in that a molecular sieve is used as the drying agent. 6. Process according to claims 1-5, characterized in that manganese (II) tris (acetylacetonate) is used as the redox cocatalyst. Process according to Claims 1 to 6, characterized in that 2,2-trifluoroethanol is used as the β-fluoroalkanol and palladium (II) dibromide as the palladium-containing catalyst. 8. Process according to claims 2-7, characterized in that the base 20 is 1,2,2,6,6-pentamethylpiperidine. 9. Process according to claims 3-6, characterized in that tetrabutyl ammonium bromide is used as the phase transfer agent. 7908995