PROCESS FOR PREPARING DI(FLUOROALKYL CONTAINING GROUP-SUBSTITUTED ALKYL) PHOSPHATE SALT

Abstract: A di(fluoroalkyl containing group-substituted alkyl) phosphate salt which is useful for a surface active agent, a water- and/or oil-repellent for fiber or paper or an oil resistant agent, can be prepared a process which comprises hydrolyzing a mono-sec.- or tert.-alkyl di(fluoro­ alkyl containing group-substituted alkyl) phosphate with a base.

Description: BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a process for preparing a di(fluoroalkyl containing group-substituted alkyl) phosphate salt. The di(fluoroalkyl containing group-substituted alkyl) phosphate salt is useful as a surface active agent, a water- and/or oil-repellent for fiber or paper or an oil resistant agent. DESCRIPTION OF THE RELATED ART Processes for preparing fluoroalkyl containing group-substituted alkyl phosphate esters are disclosed in, for example, Japanese Patent Publications Nos. 7776/1979, 29875/1981 and 48158/1982 and Japanese Patent Kokai Publication No. 64990/1985. However, the phosphate esters which are obtained by the above processes have wide distribution of composition which contains two or three of a monoalkyl ester, a dialkyl ester and a trialkyl ester. Of these three esters, the di(fluoroalkyl containing group-substituted alkyl) phosphate ester has the highest oil resistance, but is not produced in a high selectivity and contains relatively large amounts of monoalkyl and trialkyl esters. An yield of dialkyl esters is at most about 80% by weight, as described in Examples of Japanese Patent Publication No. 7776/1979. It is desired to increase the selectivity of dialkyl esters. Japanese Patent Publication No. 25190/1981 discloses a process for preparing phosphate esters. The process comprises hydrolyzing a reaction product of an alkanol containing a perfluoroalkyl group with a mixture of a phosphorus oxyhalide and phosphoric acid. SUMMARY OF THE INVENTION An object of the present invention is to provide a process for preparing a fluoroalkyl containing group-substituted alkyl phosphate ester by which a dialkyl ester is produced in a high selectivity. This and other objects of the present invention are achieved by a process for preparing a di(fluoroalkyl containing group-substituted alkyl) phosphate salt which comprises hydrolyzing a mono-sec.- or tert.-alkyl or -alkenyl di(fluoroalkyl containing group-substituted alkyl) phosphate with a base. DETAILED DESCRIPTION OF THE INVENTION Illustrative types of the di(fluoroalkyl containing group-substituted alkyl) phosphate salt produced by the process according to the present invention are of the formula: [R f -A¹ k -(CH₂) m -O]₂PO-OA² (I) wherein each R f is independently a perfluoroalkyl group or ω-hydroperfluoroalkyl group having 3 to 21 carbon atoms, each A¹ is independently a divalent group which bonds R f to -(CH₂) m -, A² is an alkaline metal or an ammonium group which may be substituted with an alkyl and/or hydroxyalkyl group, k is 0 or 1, and m is an integer of 1 to 4. R f in the formula (I) may be linear, branched, cyclic (for example, perfluorocyclohexyl) or combination thereof. A¹ is, for example, -COO-, -SO₂, -O-, -(CH₂)₃-O-, -S-, -(CH₂) p -NR′-, -CH₂CH(OR′)-, -CO-NR′- or -SO₂-NR′- in which R′ is a hydrogen or an alkyl group having 1 to 5 carbon atoms and p is an integer of 1 to 6. Specific examples of the di(fluoroalkyl containing group-substituted alkyl) phosphate salt of the formula (I) are: (C₄F₉CH₂CH₂O)₂POONH₂(C₂H₄OH)₂ [(CF₃)₂CF(CF₂)₆CH₂CH₂O]₂POONH₂(C₂H₄OH)₂ (C₈F₁₇CH₂CH₂O)₂POONH₂(C₂H₄OH)₂ (C₆F₁₃CH₂CH₂O)₂POONH₂(C₂H₄OH)₂ (C₁₀F₂₁CH₂CH₂O)₂POONH₂(C₂H₄OH)₂ (C₁₂F₂₅CH₂CH₂O)₂POONH₂(C₂H₄OH)₂ (C₁₄F₂₉CH₂CH₂O)₂POONH₂(C₂H₄OH)₂ (C₈F₁₇CH₂CH₂O)₂POONH₄ (C₈F₁₇CH₂CH₂O)₂POONH(C₂H₄OH)₃ [C₈F₁₇SO₂N(C₂H₅)CH₂CH₂O]₂POONH₄ [C₆F₁₃SO₂N(C₂H₅)CH₂CH₂O]₂POONH₄ [C₁₀F₂₁SO₂N(C₂H₅)CH₂CH₂O]₂POONH₄ [C₁₂F₂₅SO₂N(C₂H₅)CH₂CH₂O]₂POONH₄ [C₁₄F₂₉SO₂N(C₂H₅)CH₂CH₂O]₂POONH₄ [C₈F₁₇SO₂N(C₂H₅)CH₂CH₂O]₂POONH₂(CH₂CH₂OH)₂ [C₈F₁₇SO₂N(C₂H₅)CH₂CH₂O]₂POONH(CH₂CH₂OH)₃ [C₈F₁₇SO₂N(C₃H₇)CH₂CH₂O]₂POONH₂(CH₂CH₂OH)₂ [C₈F₁₇CON(C₂H₅)CH₂CH₂O]₂POONH(CH₂CH₂OH)₃ (C₈F₁₇COOCH₂CH₂O)₂POONH₄ (C₈F₁₇SO₂CH₂CH₂O)₂POONH₄ [C₈F₁₇(CH₂)₃OCH₂CH₂O]₂POONH₄ [C₈F₁₇CH₂CH(OH)CH₂O]₂POONH₄ To prepare the di(fluoroalkyl containing group-substituted alkyl) phosphate salt of the formula (I), an alkyl ester of di(fluoroalkyl containing group-substituted alkyl) phosphate is hydrolyzed with a base. The alkyl ester of di(fluoroalkyl containing group-substituted alkyl) phosphate is preferably of the formula: [R f -A¹ k -(CH₂) m -O]₂PO-OR (II) wherein R is a secondary or tertiary alkyl or alkenyl group having 3 to 9 carbons, and R f , A¹, k and m are the same as defined above. An alcoholic residue which is formed by the secondary or tertiary alkyl or alkenyl group is easily removed by hydrolysis to form the diester phosphate salt of the formula (I). Specific examples of the alkyl ester of di(fluoroalkyl containing group-substituted alkyl) phosphate of the formula (II) are: (C₄F₉CH₂CH₂O)₂POOCH(CH₃)₂ [(CF₃)₂CF(CF₂)₆CH₂CH₂O]₂POOCH(CH₃)₂ (C₈F₁₇CH₂CH₂O)₂POOCH(CH₃)₂ (C₆F₁₃CH₂CH₂O)₂POOCH(CH₃)₂ (C₁₀F₂₁CH₂CH₂O)₂POOCH(CH₃)₂ (C₁₂F₂₅CH₂CH₂O)₂POOCH(CH₃)₂ (C₁₄F₂₉CH₂CH₂O)₂POOCH(CH₃)₂ (C₈F₁₇CH₂CH₂O)₂POOC(CH₃)₃ (C₈F₁₇CH₂CH₂O)₂POOCH₂CH₂CH(CH₃)₂ [C₈F₁₇SO₂N(C₂H₅)CH₂CH₂O]₂POOCH(CH₃)₂ [C₆F₁₃SO₂N(C₂H₅)CH₂CH₂O]₂POOCH(CH₃)₂ [C₁₀F₂₁SO₂N(C₂H₅)CH₂CH₂O]₂POOCH(CH₃)₂ [C₁₂F₂₅SO₂N(C₂H₅)CH₂CH₂O]₂POOCH(CH₃)₂ [C₁₄F₂₉SO₂N(C₂H₅)CH₂CH₂O]₂POOCH(CH₃)₂ [C₈F₁₇SO₂N(C₂H₅)CH₂CH₂O]₂POOC(CH₃)₃ [C₈F₁₇SO₂N(C₂H₅)CH₂CH₂O]₂POOCH₂CH₂CH(CH₃)₂ [C₈F₁₇SO₂N(C₃H₇)CH₂CH₂O]₂POOCH(CH₃)₂ [C₈F₁₇CON(C₂H₅)CH₂CH₂O]₂POOCH(CH₃)₂ [C₈F₁₇COOCH₂CH₂O]₂POOCH(CH₃)₂ [C₈F₁₇SO₂CH₂CH₂O]₂POOCH(CH₃)₂ [C₈F₁₇(CH₂)₃OCH₂CH₂O]₂POOCH₂CH(CH₃)₂ [C₈F₁₇CH₂CH(OH)CH₂O]₂POOCH(CH₃)₂ The base which is used to hydrolyze the alkyl ester of di(fluoroalkyl containing group-substituted alkyl) phosphate of the formula (II) is preferably an alkali hydroxide, an ammonium hydroxide or an amine. Examples of the alkali hydroxide are potassium hydroxide and sodium hydroxide. Examples of the amine are trimethylamine, triethylamine, tripropylamine, tributylamine, triethanolamine, diethylamine, dipropylamine, diethanolamine, ethylamine, propylamine and ethanolamine. The hydrolysis can be carried out by adding ammonium hydroxide or an amine/water mixture, or an alkali hydroxide/alcohol/water mixture to the alkyl ester of di(fluoroalkyl containing group-substituted alkyl) phosphate. The alcohol which is used in hydrolysis includes a secondary or tertiary C₃-C₆ alcohol such as isopropyl alcohol, tert.-butyl alcohol, sec.-butyl alcohol, tert.-amyl alcohol, isoamyl alcohol and sec.-amyl alcohol. Usually, the hydrolysis is carried out under an atmospheric pressure at a temperature of 80 to 100°C for 2 to 6 hours. The alkyl ester of di(fluoroalkyl containing group-substituted alkyl) phosphate of the formula (II) can be prepared by reacting a fluoroalkyl containing group-substituted alcohol of the formula: R f -A¹ k -(CH₂) m -OH (III) wherein R f , A¹, k and m are the same as defined above, with a phosphoryl monoalkoxide dihalide of the formula: RO-POX₂ (IV) wherein each X is independently halogen atom, for example, chlorine or bromine and R is the same as defined above. Specific examples of the alcohol of the formula (III) are: C₄F₉CH₂CH₂OH (CF₃)₂CF(CF₂)₆CH₂CH₂OH C₈F₁₇CH₂CH₂OH C₁₀F₂₁CH₂CH₂OH C₈F₁₇SO₂N(C₂H₅)CH₂CH₂OH C₈F₁₇SO₂N(C₃H₇)CH₂CH₂OH C₈F₁₇SO₂N(CH₃)CH₂CH₂OH In the reaction, a molar ratio of the alcohol of the formula (III) to the phosphoryl monoalkoxide dihalide of the formula (IV) is preferably from 2:1 to 2:1.2. Usually, the reaction is carried out under an atmospheric pressure at 80 to 100°C for 2 to 4 hours. The phosphoryl monoalkoxide dihalide of the formula (IV) can be prepared by reacting a secondary or tertiary alcohol of the formula: ROH (V) wherein R is the same as defined above, with a phosphoryl trihalide of the formula: POX₃ (VI) wherein X is the same as defined above. It is not preferable to use a primary alcohol instead of the secondary or tertiary alcohol of the formula (V), since the alkyl ester of di(fluoroalkyl containing group-substituted alkyl) phosphate of the formula (II) is hardly hydrolyzed. As the phosphoryl trihalide of the formula (VI), usually phosphoryl trichloride is used because of its availability, although phosphoryl tribromide and phosphoryl bromide chloride may be used. A molar ratio of the secondary or tertiary alcohol of the formula (V) to the phosphoryl trihalide of the formula (VI) is preferably about 1:1. Usually, the reaction is carried out under an atmospheric pressure at a temperature of room temperature to 70°C for 2 to 4 hours. Therefore, the di(fluoroalkyl containing group-substituted alkyl) phosphate salt of the formula (I) can be prepared by reacting the secondary or tertiary alcohol of the formula (V) with the phosphoryl trihalide of the formula (VI) to produce the phosphoryl monoalkoxide dihalide of the formula (IV), reacting the phosphoryl monoalkoxide halide of the formula (IV) with the fluoroalkyl containing group-substituted alcohol of the formula (III) to produce the alkyl ester of di(fluoroalkyl containing group-substituted alkyl) phosphate of the formula (II), and hydrolyzing the alkyl ester of di(fluoroalkyl containing group-substituted alkyl) phosphate of the formula (II) with the base. According to the present invention, the di(fluoroalkyl containing group-substituted alkyl) phosphate salt can be prepared in a purity of not less than 90% by weight. The present invention will be explained further in detail by the following Examples. Example 1 In a 200 ml flask equipped with a stirrer, a Dimroth condenser and a dropping funnel, phosphoryl trichloride (154 g, 1 mol) was charged and isopropyl alcohol (57 g, 0.95 mol) was dropwise added over 30 minutes with stirring. The reaction was exothermic and hydrogen chloride gas evolved. After completing the exothermic reaction, the reaction mixture was heated at 70°C for one hour to give a colorless liquid mixture containing POCl₃ (1 g), C₃H₇OPOCl₂ (175 g) and (C₃H₇O)₂POCl (3 g). In a one litter flask, a compound (200 g, 0.39 mol) of the formula: C n F n+1 CH₂CH₂OH wherein molar fractions of compounds which have n of 8, 10, 12, 14 and 16 respectively are 55, 26, 12, 5 and 2, was charged. While a temperature was kept at 80°C, the resultant liquid mixture (37 g) in the above was added with stirring. Hydrogen chloride evolved and the reaction started. The reaction mixture was heated to 95°C and stirred for 2 hours. Then, water (1.5 g) was added and the reaction mixture was stirred for 2 hours to give a mixture of the following composition: Diisopropyl mono(fluoroalkyl containing group-substituted alkyl) phosphate 5% by weight Monoisopropyl di(fluoroalkyl containing group-substituted alkyl) phosphate 93% by weight Tri(fluoroalkyl containing group-substituted alkyl) phosphate 2% by weight The mixture contained no ester having chlorine atom. Diethanolamine (65 g) as a hydrolyzing agent was added to the mixture. The mixture was stirred at 95°C for 3 hours. After cooling, a wax-like solid was obtained. Yield: 297 g. The final product was analyzed by ³¹P-NMR spectrum to determine its composition. The result is shown in Table. Example 2 A wax-like solid was obtained in the same manner as in Example 1 but using tert.-butyl alcohol (70.3 g, 0.95 mol) in place of isopropyl alcohol. Yield: 302 g. A composition of the final product is shown in Table. Example 3 A wax-like solid was obtained in the same manner as in Example 1 but using tert.-amyl alcohol (83.6 g, 0.95 mol) in place of isopropyl alcohol. Yield: 315 g. A composition of the final product is shown in Table. Example 4 An aqueous solution was obtained in the same manner as in Example 1 but using sodium hydroxide (20 g) and methyl alcohol (100 g) in place of diethanolamine. Yield: 352 g. A composition of the final product is shown in Table. Example 5 A wax-like solid was obtained in the same manner as in Example 1 but using diethylamine (30 g) in place of diethanolamine. Yield: 262 g. A composition of the final product is shown in Table. In the above Examples, the di(fluoroalkyl containing group-substituted alkyl) phosphate salt is di(2-perfluoroalkyl-ethyl) phosphate. However, it is obvious for those skilled in the art to prepare other di(fluoroalkyl containing group-substituted alkyl) phosphate salts, for example, di(N-alkyl perfluoroalkanesulfonamidoalkyl) phosphate salts in the same manner as in Examples. Although Examples show the processes using diethanolamine, sodium hydroxide or diethylamine as the base, it is also obvious to use other bases since a hydrolysis reaction can be carried out with any base.

Claims: A process for preparing a di(fluoroalkyl containing group-substituted alkyl) phosphate salt which comprises hydrolyzing a mono-sec.- or tert.-alkyl or -alkenyl di(fluoroalkyl containing group-substituted alkyl) phosphate with a base. A process according to claim 1, in which the di(fluoroalkyl containing group-substituted alkyl) phosphate salt is represented by the formula: [R f -A¹ k -(CH₂) m -O]₂PO-OA² (I), the alkyl or alkenyl ester of di(fluoroalkyl containing group-substituted alkyl) phosphate is represented by the formula: [R f -A¹ k -(CH₂) m -O]₂PO-OR (II) and the base is a base selected from the group consisting of an alkali hydroxide, an ammonium hydroxide and an amine, wherein each R f is independently a perfluoroalkyl group or ω-hydroperfluoroalkyl group having 3 to 21 carbon atoms, each A¹ is independently a divalent group which bonds R f to -(CH₂)m-, A² is an alkaline metal, or an ammonium group which may be substituted with an alkyl and/or hydroxyalkyl group, R is a secondary or tertiary alkyl or alkenyl group having 3 to 9 carbons, k is 0 or 1, and m is an integer of 1 to 4. A process for preparing a di(fluoroalkyl containing group-substituted alkyl) phosphate salt which comprises reacting a secondary or tertiary alcohol with phosphoryl trihalide to produce a phosphoryl monoalkoxide dihalide, reacting the phosphoryl monoalkoxide dihalide with a fluoroalkyl containing group-substituted alcohol to produce a mono-sec.- or tert.-alkyl or -alkenyl di(fluoroalkyl containing group-substituted alkyl) phosphate, and hydrolyzing the mono-sec.- or tert.-alkyl or -alkenyl di(fluoroalkyl containing group-substituted alkyl) phosphate with a base. A process according to claim 3, in which the di(fluoroalkyl containing group-substituted alkyl) phosphate salt is represented by the formula: [R f -A¹ k -(CH₂) m -O]₂PO-OA² (I), the secondary or tertiary alcohol is represented by the formula: ROH (V), the phosphoryl trihalide is represented by the formula: POX₃ (VI), the phosphoryl monoalkoxide dihalide is represented by the formula: RO-POX₂ (IV), the fluoroalkyl containing group-substituted alcohol is represented by the formula: R f -A¹ k -(CH₂) m -OH (III), the alkyl or alkenyl ester of di(fluoroalkyl containing group-substituted alkyl) phosphate is represented by the formula: [R f -A¹ k -(CH₂) m -O)₂PO-OR (II) and the base is a base selected from the group consisting of an alkali hydroxide, an ammonium hydroxide and an amine, wherein each of R f , A¹, A², R, k and m has the meaning as in claim 2 and each X is independently halogen, preferably chlorine or bromine.

Inventors: IIDA, SHIGEHARU, YOSHIDA, TUTOMU
Applicants: DAIKIN INDUSTRIES, LIMITED
Application year: 1988
Main classification: C07F9
IPC codes: C07F9