HUNG MING-HONG (US)
| WO2009094344A1 | 2009-07-30 |
KUDRYAVTSEV, I. YU. ET AL., IZVESTIYA AKADEMII NAUK SSSR, SERIYA KHIMICHESKAYA, 1982, pages 2535 - 2540
| CLAIMS What is claimed is: 1 . A process for manufacturing a polyfluoroalkanoyi phosphorodichlondate, said process comprising: reacting a polyfluorinated alkanol having the general formula Rf- CH2-OH, wherein Rf is a linear or branched d-Cs perfluoroalkyl group optionally interrupted by O, with at least 4 moles of POCI3 per mole of Rf-CH2-OH in the presence of 0.1 to 0.2 moles of LiCI catalyst per mole of Rf-CH2-OH at a temperature between 95°C and 1 10°C to form a polyfluoroalkanoyi phosphorodichlondate of the general formula Rf-CH2-O-P(O)CI2. 2. The process according to claim 1 , wherein said polyfluorinated alkanol is selected from the group consisting of pentafluoropropanol, heptafluoro -1 - butanol, 2,3,3,3-tetrafluoro-2- (heptafluoropropoxy)-l -propanol, and 2,5-di(trifluoromethyl)-3,6-dioxa- 1 H,1 H-perfluoro-1 -nonanol. 3. The process according to claim 1 , wherein said polyfluorinated alkanol is reacted with 4 to 8 moles of POCI3 per mole of polyfluorinated alkanol. 4. The process according to claim 1 wherein the molar ratio of polyfluoroalkanoyi phosphorodichloridate to byproduct polyfluoroalkanoyi phosphorochloridate is at least 10 to 1 . 5. The process according to claim 1 having a yield of polyfluoroalkanoyi phosphorodichloridate of at least 50%. 6. The process according to claim 5 having a yield of polyfluoroalkanoyi phosphorodichloridate of at least 75 wt%. |
FLUORINATED ALCOHOLS
FIELD OF THE INVENTION
This invention relates to a process for producing polyfluoroalkanoyl phosphorodichloridates; more particularly, it relates to a process for producing polyfluoroalkanoyl phosphorodichloridates by reaction of the corresponding polyfluoroalkanol with POCI3 in presence of LiCI as catalyst. BACKGROUND OF THE INVENTION
It is known that certain fluoroalkylphosphoric acid esters are useful as dispersing agents in the emulsion polymerization of fluoroelastomers (WO 2009/094344 A1 ). These esters are of the formula X-Rf-(CH 2 ) n -0- P(O)(OM) 2 , wherein n = 1 or 2, X = H or F, M = a univalent cation, and Rf is a C 4 - C6 fluoroalkyl or fluoroalkoxy group (branched or non-branched). In the first step of the synthesis of these fluoroalkylphosphoric acid esters, the phosphorodichloridate is prepared by reaction of the corresponding fluoroalkanol with phosphorous oxychloride. The di-and tri-esters are not as suitable dispersing agents as are the mono-esters in the emulsion polymerization of fluoroelastomers. Thus, it would be desirable if the phosphorylation reaction yielded exclusively the polyfluoroalkanoyl phosphorodichloridate.
Kudryavtsev, I. Yu. et al., Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1 1 , pp. 2535-2540 (1982) discloses catalytic phosphorylation of a series of polyfluorinated alkanols by phosphorous oxychloride using Group I metal chlorides as catalyst. The results indicate that the LiCI catalyzed phosphorylation reaction of polyfluorinated alkanols with POCI3 produced predominantly polyfluoroalkanoyl phosphates and polyfluoroalkanoyl phosphorochloridates and very little or no
polyfluoroalkanoyl phosphorodichloridate.
SUMMARY OF THE INVENTION A relatively selective process has been developed for the
manufacture of a polyfluoroalkanoyi phosphorodichloridate from the LiCI catalyzed reaction of the corresponding polyfluorinated alkanol with POCI3.
Accordingly, an aspect of the instant invention is a process for preparing a polyfluoroalkanoyi phosphorodichloridate, said process comprising: reacting a polyfluorinated alkanol having the general formula R f -CH 2 -OH, wherein R f is a linear or branched d-Cs perfluoroalkyi group optionally interrupted by O, with at least 4 moles of POCI3 per mole of R f -CH 2 -OH in the presence of 0.1 to 0.2 moles of LiCI catalyst per mole of R f -CH 2 -OH at a temperature between 95°C and 1 10°C to form a polyfluoroalkanoyi phosphorodichloridate of the general formula Rf-CH 2 -O-P(O)Cl2.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is a process for manufacturing a
polyfluoroalkanoyi phosphorodichloridate from a polyfluorinated alkanol by phosphorylation using POCI3 as the reagent in the presence of LiCI as catalyst.
In the process of the present invention, polyfluoroalkanoyi phosphorodichloridates are prepared from polyfluorinated alkanols having the general formula R f -CH 2 -OH by a phosphorylation reaction, wherein R f is a linear or branched Ci-Cs perfluoroalkyi group optionally interrupted by oxygen atom: R f -CH 2 -OH + POCI3/L1CI > R f -CH 2 -O-P(O)CI 2 (I) +
(R f -CH 2 -O) 2 -P(O)CI (II) +
(R f -CH 2 -O) 3 -P(O) (III) wherein the predominant product is the polyfluoroalkanoyi
phosphorodichloridate (I). Byproducts polyfluoroalkanoyi
phosphorochloridate (II) and polyfluoroalkanoyi phosphate (III) are formed in minor amounts. The molar ratio of polyfluoroalkanoyi phosphorodichloridate to polyfluoroalkanoyl phosphorochloridate is at least 10 to 1 in the process of this invention. Most of the byproducts and excess POCI3 may be separated from the phosphorodichloridate by distillation.
Specific polyfluorinated alkanols that may be employed in the process of the invention include, but are not limited to 2,3,3,3-tetrafluoro-2- (heptafluoropropoxy)-l -propanol; pentafluoropropanol; heptafluoro-1 - butanol; and 2,5-di(trifluoromethyl)-3,6-dioxa-1 H,1 H-perfluoro-1 -nonanol.
In order to minimize byproduct formation, POCI3 is used in the process at the level of at least 4 moles (preferably 4-8 moles) POCI3 per mole of polyfluoroalkanol. Other phosphorylation reagents (e.g.
phosphorous pentoxide) should not be used because the reaction produces a high proportion of byproducts.
The use of LiCI as catalyst for the phosphorylation of
polyfluoroalkylanols in the presence of POCI 3 enhances the reaction rate and raises the yield. In order to minimize byproduct formation while optimizing reaction rate and yield, LiCI is used in the process of the invention at the level of between 0.1 and 0.2 moles (preferably between 0.1 and 0.15 moles) LiCI per mole of polyfluoroalkanol. Other metal salts should not be employed as catalysts because the reaction rate is slower and more byproducts result from the reaction.
The phosphorylation process of the invention is carried out at a temperature between 95°C and 1 10°C. Higher temperatures increase the amount of byproducts formed, while lower temperatures decrease the reaction rate. Reaction times are typically 1 -5 hours or less, preferably 2-3 hours.
The yield of polyfluoroalkanoyl phosphorodichloridate produced by the process of the invention is at least 50%, preferably at least 75%.
EXAMPLES Example 1
Phosphorylation of 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)-1 -propanol A reaction flask was charged with 2,3,3,3-tetrafluoro-2-
(heptafluoropropoxy)-l -propanol (HFPO-dimer alcohol) (94.8 grams, 0.3 moles), LiCI (2.54 grams, 0.06 moles), and POCI 3 (184 grams, 1 .20 moles). This reaction mixture was heated at about 105°C for 2 hours.
Gas chromatography analysis (6' x ¼" (1 .8 m x 0.64 cm) OV-210 on
Chromosorb®/PAW-DMCS packed column, 160°C isothermal, thermal conductivity detector) indicated that the reaction was almost completed, and that the product ratio of 2-trifluoromethyl-3-oxa-2,4,4,5,5,6,6,6- octafluoro-hexanoyl phosphorodichloridate (HFPO-DC) to the byproduct 2- trifluoromethyl-3-oxa-2,4,4,5,5,6,6,6-octafluoro-hexanoyl
phosphorochloridate (HFPO-DCC) was between 95-88 to 5-12.
The excess POCI 3 was first distilled off, then the desired product (HFPO-DC) was distilled at about 80°C/20mm Hg. Two runs of the process gave the total yield of 191 grams of highly pure product (>99%) as a clear, colorless liquid (74% yield).
Comparative Example A
The process of Example 1 was repeated except that CaC^ (6.67 grams, 0.06 moles) was used in place of LiCI catalyst. The reaction took 6-8 hours to complete and resulted in a molar ratio of desired product HFPO-DC to byproduct HFPO-DCC of 5-7 to 1 . Comparative Example B
The process of Example 1 was repeated except that no catalyst was employed. The reaction did not reach completion within 12 hours. Less than 5% of the HFPO-dimer alcohol was converted to HFPO-DC. Example 2
Phosphorylation of pentafluoropropanol
Pentafluoropropanol (C 2 F 5 -CH 2 OH) (20.1 grams, 0.134 moles) was mixed with POCI3 (85 grams, 0.554 moles) and lithium chloride (0.85 grams, 0.02 moles). The reaction mixture was heated at 105°C for less than 30 min.
Gas chromatography analysis indicated that all the starting material was converted to the phosphorylated products C2F 5 -CH 2 O-P(O)Cl2 and (C 2 F5-CH 2 O) 2 -P(O)CI (molar ratio 100 to 4.8).
Distillation gave the pure mono-phosphorylation product C 2 F 5 - CH 2 O-P(O)CI 2 as a clear colorless liquid, bp. 53-54°C/1 1 mm Hg, yield > 50%.
1 H NMR (400 MHz, CDCI3): 4.67 ppm (qm, J = 1 1 .4 Hz, 2H); 19 F NMR (376.89 MHz, CDCI 3 ): -83.9 ppm (s, 3F), -124.3 ppm (s, 2F)
Example 3
Phosphorylation of heptafluoro-1 -butanol
Heptafluoro-1 -butanol (C 3 F 7 -CH 2 OH) (13.4 grams, 0.067 moles) was mixed with POCI3 (42.5 grams, 0.277 moles) and lithium chloride (0.43 grams, 0.01 moles). The reaction mixture was heated at 105°C for less than 30 min.
Gas chromatography analysis indicated that all the starting material was converted to the phosphorylated products CsF 7 -CH 2 O-P(O)CI 2 and (C 3 F 7 -CH 2 O) 2 -P(O)CI (molar ratio 100 to 5).
Distillation gave the pure mono-phosphorylation product C3F7- CH 2 O-P(O)CI 2 as a clear colorless liquid, bp. 55-60°C/1 1 mm Hg, yield > 55%.
1 H NMR (400 MHz, CDCI3): 4.71 ppm (qm, J = 1 1 .8 Hz, 2H); 19 F NMR (376.89 MHz, CDCI 3 ): -81 .3 ppm (t, J = 18.4 Hz, 3F), -121 .2 ppm (m, 2F), - 127.8 (s, br, 2F).
Example 4
Phosphorylation of 2,5-di(trifluoromethyl)-3,6-dioxa-1 H,1 H-perfluoro-1 - nonanol 2,5-di(trifluoromethyl)-3,6-dioxa-1 H,1 H-perfluoro-1 -nonanol [C 3 F 7 - O-CF(CF3)CF 2 O-CF(CF3)-CH 2 OH] (HFPO-trimer alcohol) (10 grams, 0.0207 moles) was mixed with POCI 3 (13 grams, 0.0848 moles) and lithium chloride (0.14 grams, 0.0033 moles). The reaction mixture was heated at 105°C for 5 hours.
Gas chromatography analysis indicated that all the starting material was converted to the phosphorylated product C 3 F 7 -O-CF(CF 3 )CF 2 O- CF(CF 3 )-CH 2 O-P(O)CI 2 and no di-phosphorylated [C 3 F 7 -O-CF(CF 3 )CF 2 O- CF(CF 3 )-CH 2 O] 2 -P(O)CI was formed. Distillation gave the mono- phosphorylation product C 3 F 7 -O-CF(CF 3 )CF 2 O-CF(CF 3 )-CH 2 O-P(O)CI 2 as a clear colorless liquid, bp. 41 -44°C/0.3 mm Hg, yield 63%.
1 H NMR (400 MHz, CDCI 3 ): 4.73 ppm (m, 2H); 19 F NMR (376.89 MHz, CDCIs): -79.5 to -85.0 ppm (m, 13F), -103.1 ppm (m, 2F), -135.6 (m, 1 F), - 145.3 (m, 1 F)
Comparative Example C
2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)-1 -propanol (HFPO-dimer alcohol) (20 grams, 0.0633 moles) was mixed with POCI 3 (3.24 grams, 0.021 1 moles), and lithium chloride (0.40 grams, 0.0094 moles). The reaction mixture was heated at 105°C for 1 hour.
Gas chromatography indicated that only the di-adduct and tri- adduct were formed (molar ratio 2:15). No mono-phosphorylation product (i.e. no phosphorodichloridate) was observed. Additional heating for 1 hour at 105°C did not change the di-adduct to tri-adduct ratio.
Comparative Example D
Heptafluoro-1 -butanol (13.4 grams, 0.067 moles) was mixed with POCI 3 (3.4 grams, 0.022 moles), and lithium chloride (0.43 grams, 0.01 moles). The reaction mixture was heated to 125-130°C for about 2 hours. Gas chromatography indicated that only the di-adduct [(C 3 F 7 -
CH 2 O) 2 -P(O)CI] and tri-adduct [(C 3 F 7 -CH 2 O) 3 -P(O)] were present in the product mixture (molar ratio 1 : 16.8). No mono-phosphorylated product was observed.
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