PROCESS FOR THE FORMATION OF HYDROCARBYL BIS(DIHYDROCARBYL PHOSPHATE)

Abstract: A process for forming a composition containing over, for example, about 90 % by weight of an alkylene-arylene bridging group-containing bis(diphenyl phosphate) compound and less than, for example, 10 % by weight of monophosphate by-product. This process involves the reaction of a composition containing a diphenyl halophosphate and an alkylene-arylene bridging group-containing diol, in the presence of a catalytic amount of a Lewis acid catalyst, utilizing a means, during the course of the reaction, for removal of hydrohalide by-product. The preferred means that are used for removal of hydrohalide by-product include: utilizing vacuum to remove such by-product; utilizing sparging with an inert gas; utilizing vacuum to remove such by-product in combination with performing the reaction in a hydrocarbon solvent; utilizing sparging with an inert gas in combination with performing the reaction in a hydrocarbon solvent; and utilizing vacuum and sparging with an inert gas in combination with performing the reaction in a hydrocarbon solvent to remove such by-product.

Description: PROCESS FOR THE FORMATION OF HYDROCARBYL BIS(DIHYDROCARBYL PHOSPHATE) Background of the Invention Processes for the synthesis of a hydrocarbyl bιs(dihydrocarbyl phosphate) by the reaction of a hydrocarbyl diol with a dihydrocarbyl halophosphate in the presence of a Lewis acid catalyst are known to the prior art. For example, U.S. Patent No. 3,254,973 to J.J. Giammaria et al. illustrates such a general reaction beginning at Col 6, line 20 but teaches the use of nitrogen gas to remove hydrohalide by-product at the end of the reaction, rather than during the course of the actual reaction itself while the product composition is being formed. This patent does not discuss anything about the purity of the product that is formed by its technique. U.S Patent No. 4,133,846 to J.A Albright illustrates an analogous reaction, does not show the nitrogen sparge aspect, and merely suggests (at Col. 4, lines 45-47) that an organic solvent can be used during the reaction without any description of an advantage for doing so. It too is silent in regard to the product purity as compared to one made without nitrogen sparging, for example, and its Examples fail to show either the use of solvent or nitrogen sparging. More recent U.S Patent No 4,343,732 to T. Zama et al. shows the reaction of certain diols, phosphorus oxychioπde, and certain alcohols and phenois, in the presence of aluminum chloride as a catalyst, indicates (at Col 4, lines 21 -22) that inert solvents, such as toluene and xylene. may be used, but also describes no advantage for the use of a solvent in its particular process. It has unexpectedly been found that when the aforementioned type of process is practiced without substantially concurrent means to remove hydrohalide by-product, the product that is formed has a lower assay and contains a greater degree of undesired monophosphate by-product, such as tπphenyl phosphate and isopropenyl phenyl diphenyl phosphate as well as other impurities from product breakdown. Applicant's PCT International Patent Publication No. 96/13508 describes a process comprising the reaction of a composition consisting essentially of diaryl halophosphate and an alkylene-arylene bridging group-containing diol, in the presence of a catalytic amount of a Lewis acid catalyst, with the reaction being run in a hydrocarbon solvent in order to achieve the removal of undesired hydrohalide byproduct from the reaction medium in order to increase the yield of the desired hydrocarbyl bis(dihydrocarbyl phosphate). Summary of the Invention The present invention is a further improvement of the process described in PCT International Patent Publication No. 96/13508. The present invention relates to a process for forming a composition containing more bisphosphate and less undesired monophosphate by-product with the desired alkylene-arylene bridging group- containing bis(diphenyl phosphate) compound, which is normally prone to be formed with such monophosphate by-product formation. The instant process, more particularly, comprises the reaction of a composition consisting essentially of diaryl halophosphate and an alkylene-arylene bridging group-containing diol, in the presence of a catalytic amount of a Lewis acid catalyst, utilizing a means, during the reaction, for removal of hydrohalide by-product which is selected from the group consisting of: utilizing vacuum to remove such by-product; utilizing sparging with an inert gas to remove such by-product; utilizing vacuum to remove such by-product in combination with performing the reaction in a hydrocarbon solvent; utilizing sparging with an inert gas in combination with performing the reaction in a hydrocarbon solvent; and utilizing vacuum and sparging with an inert gas in combination with performing the reaction in a hydrocarbon solvent to remove such by-product. The present invention, in another embodiment thereof, relates to an alkylene-arylene bridging group-containing bis(diphenyi phosphate) composition, normally prone to be formed with undesired monophosphate by-product, which composition is formed from the reaction of a diaryl halophosphate and an alkylene-arylene bridging group- containing diol, as previously described. This desired composition contains more than 85% by weight of bisphosphate and less than 15%, by weight, of undesired monophosphate by-products. Detailed Description of the Invention The present process is one which is intended to synthesize a hydrocarbyl bisphosphate composition containing more bisphosphate (preferably over 85%, most preferably over 90%) and less undesired monophosphate by-product (preferably less than 15%, most preferably less than 10%), with the desired hydrocarbyl bisphosphate compound which is of the following formula: RO O 0 OR Ml ll/ P-O-R'-O-P / \ RO OR where R can be hydrocarbyl (such as, substituted or unsubstituted aryl, e.g., phenyl) and R' is an alkylene-arylene bridging group, of the general formula -Ar-R"-Ar-, where Ar is arylene, such as phenylene and R" is alkylene. Representative diols of this type can be represented by Bisphenoi A. Conventional processes for forming such compounds result in the formation of undesired monophosphate by-products, such as triphenyl phosphate and/or isopropenyl phenyl diphenyl phosphate, above the levels claimed herein due to the nature of the bridging group R', and a lower assay product. The dihydrocarbyl halophosphate reactant used in the instant process has the formula RO O \ll P-X / RO where R is hydrocarbyl (e g., substituted or unsubstituted aryl, such as phenyl) and X is halogen Preferred compounds are the diarylchlorophosphat.es (e.g., diphenyl- chlorophosphate). This reactant is preferably present at about 2:1 (on a molar basis) to the following dihydroxy reactant. The dihydroxy reactant (HOROH) is used to form the bridging group R' in the final compounds. The reaction is run at elevated temperature (above about 20°C) using an effective amount (e.g., about 0.01 % to about 1 % based upon the weight of the selected dihydrocarbyl halophosphate reagent) of a Lewis acid catalyst. Such catalysts include such transition metal halides as magnesium chloride, aluminum chloride, zinc chloride, titanium tetrachloride and the like In one embodiment of the invention, a suitable inert gas to the reaction, such as nitrogen, can be used to drive off the undesired product during the course of the reaction to enable production of the desired bisphosphate compound in the final composition. If desired, the use of vacuum can be used to remove the undesired hydrogen halide during the reaction. In yet other embodiments of the invention a combination of vacuum and/or sparging gas in combination with the solvent technique described and claimed in PCT International Patent Publication No. 96/13508 can be used to enable production of the desired bisphosphate compound in the final composition. The technolgy described and claimed in that PCT patent publication relies upon the presence of an additional amount of a liquid hydrocarbon, for example, an aliphatic hydrocarbon, such as heptane, or an aromatic solvent, such as toluene, to assist, as a "chaser", in driving off the hydrogen halide by-product during the course of the reaction rather than after the reaction has been run as shown in U.S Patent No. 3,254,973 to J J Giammaria et al. Generally speaking, the amount of solvent that is used in accordance with the present invention in combination with vacuum and/or sparging will be up to about 100% by weight of the weight of diol and halophosphate, preferably up to about 50%, more preferably up to about 20%. The use of this liquid hydrocarbon allows for a high purity product to be formed at lower temperatures than possible if the liquid hydrocarbon were absent. The present invention is illustrated by the Examples which follow. EXAMPLE 1 This Example illustrates an embodiment of the present invention. Diphenyl chlorophosphate (0.5 mole), Bisphenol A (0.25 mole), magnesium chloride (2.63 x 10-3 moles), and heptane (20 wt%) were heated to reflux (about 99°C) for six hours. The disappearance of the hydroxyl functionality in the Bisphenol A reagent was monitored by infrared analysis. The reaction mixture was washed with 5 wt% caustic followed by two water washes. Liquid chromatographic analysis of the product showed the following composition: Bisphenol A bis(diphenyl phosphate), also termed "P2" (92.3 t%); the next higher oligomer "P3" of the foregoing (2.4 area%); triphenyl phosphate (1.5 wt%); and isopropenylphenyl diphenyl phosphate (0.5 area%). The material solidified upon cooling and had a melting point of from about 47°C to about 55°C. EXAMPLE 2 The same reaction as illustrated in Example 1 was carried out under vacuum of 200 mbar to remove hydrogen chloride. The following composition was obtained: Bisphenol A bis(diphenyl phosphate) "P2": 91% by weight Triphenyl phosphate: 1.6% by weight Isopropenyl phenyl diphenyl phosphate: 4.7% by area (about 0.5 wt%) Bisphenol A oligomeric(diphenyl phosphate) "P3" 2 3% by area The melting range of the product was 45-55°C EXAMPLE 3 The same reaction as illustrated in Example 1 was carried out under nitrogen sparge to remove hydrogen chloride The following composition was obtained Bisphenol A bιs(dιphenyl phosphate) "P2" 90% by weight Triphenyl phosphate 1 9% by weight Isopropenyl phenyl diphenyl phosphate 8 5% by area (about 1 t%) Bisphenol A olιgomerιc(dιphenyl phosphate) "P3" 2 4% by area The melting range of the product was 45-55°C COMPARATIVE EXAMPLE 4 The same reaction as illustrated in Example 1 was carried out without the use of either solvent or other physical means (e g , vacuum or nitrogen sparge) to remove hydrogen chloride by-product The following composition was obtained Bisphenol A bιs(dιphenyl phosphate) "P2" 81 % by weight Triphenyl phosphate 4 4% by weight Isopropenyl phenyl diphenyl phosphate 14 7% by area Bisphenol A olιgomerιc(dιphenyl phosphate) "P3" 1 8% by area COMPARATIVE EXAMPLE 5 The same reaction as illustrated in Example 1 was carried out with nitrogen sparging at the end of the reaction, as suggested in U S Patent No 3,254,973 to J J Giammaria et al , rather than during the course of the reaction in accordance with one embodimnent of the present invention The following composition was obtained Bisphenol A bis(diphenyl phosphate) "P2": 80.4% by weight Triphenyl phosphate: 4.4% by weight Isopropenyl phenyl diphenyl phosphate: 9.8% by area Bisphenol A oligomeric(diphenyl phosphate) "P3": 2.2% by area EXAMPLE 6 This Example illustrates the introduction of oligomers into the composition by adding monophenyl dichlorophosphate (MPCP) to the reaction mixture in order to keep it liquid. Diphenyl chlorophosphate (588 g, 2.19 moles), monophenyl dichlorophosphate (12.0 g, 0.057 mole), Bisphenol A (262.8 g, 1.15 moles), magnesium chloride (2.5 g) and n-heptane (173.2 g, 20% by weight of reaction mixture) were heated to reflux temperature of heptane (99-100°C) and kept at that temperature for six hours. Heptane was distilled to increase the reaction temperature to 140°C. It was kept at 140°C for an additional eight hours. The reaction mixture was then washed at 60°C with 1.2 liters of 2% caustic, followed by 1.2 liters of 1 % caustic and 2 x 1.2 liters of water. After drying, there was obtained 736.4 g of a hazy liquid (94.6%) which was filtered through CELITE filter aid. The acid number was 0.011 mg KOH/g, and LC analysis gave the following results: 84.3% by wt. P2, 1.5% by wt. TPP, 0.09% by wt. phenol, 8.4% by area P3, 0.9% by area of half-ester, and 2.3% by area (0.2% by wt.) of isopropenylphenyl diphenyl phosphate. EXAMPLE 7 In this Example, Bisphenol A is used as a reagent with a 95:5 weight ratio of diphenyl chlorophosphate (DPCP)/MPCP. Diphenyl chlorophosphate (571 g, 2.13 moles), monophenyl dichlorophosphate (30.8g, 0.146 mole), magnesium chloride (2.5 g) and n-heptane 178.3 g (20% by wt. of reaction mixture) were heated to reflux temperature of heptane (99-100°C) for five hours. At the end of that time, heptane was distilled, and the reaction temperature was increased to 140°C. It was kept at 140°C for an additional six hours. The reaction mixture was then washed at 60°C with 1.8 liters of 2% caustic (no layer separation with 1.2 liters), followed by 1.2 liters of 1% caustic and 2 x 1.2 liters of water. After drying, there are left 731.1 g (9.8%) of a hazy light yellow oil which was filtered through CELITE filter aid. The acid number was 0.02 mm KOH/g, LC analysis gave the following results: 75% by wt. P2, 1 4% by wt. TPP, 0.15% by wt. phenol, 14.7% by area P3 2.6% by area P4 and 1.8% by area (0.2% by wt.) of isopropenylphenyl diphenyl phosphate. The foregoing Examples should not be construed in a limiting sense since they are intended to merely illustrate certain embodiments of the present invention. The scope of protection sought is set forth in the claims which follow.

Claims: Claims 1. A process for forming a composition comprising an alkylene-arylene bridging group-containing bis(diphenylphosphate) compound, normally prone to monophosphate by-product formation, with the formation of more bisphosphate and less of such monophosphate by-product, which process comprises the reaction of a composition comprising diaryl halophosphate and alkylene-arylene bridging group-containing diol, in the presence of a catalytic amount of a Lewis acid catalyst, utilizing a means, substantially concurrent with the course of the reaction, for the removal of hydrohalide by-product. 2. A process according to claim 1 , characterized in that the means for the removal of hydrohalide by-product is selected from the group consisting of: utilizing vacuum to remove such by-product; utilizing sparging with an inert gas; utilizing vacuum to remove such by-product in combination with performing the reaction in a hydrocarbon solvent; utilizing sparging with an inert gas in combination with performing the reaction in a hydrocarbon solvent; and utilizing vacuum and sparging with an inert gas in combination with performing the reaction in a hydrocarbon solvent to remove such by-product. 3. A process according to claim 1 or 2, characterized in that the diphenyl halophosphate is diphenyl chlorophosphate. 4. A process according to any one of the preceding claims, characterized in that the diol is Bisphenol A. 5. A process according to any one of the preceding claims, characterized in that the diphenyl halophosphate is diphenyl chlorophosphate and the diol is Bisphenol A. 6. A process according to any one of the preceding claims, characterized in that the Lewis acid catalyst is magnesium dichloride. 7. A process according to any one of the preceding claims, characterized in that a hydrocarbon solvent is present at up to about 20% by weight of the reaction medium. 8. A process according to claim 7, characterized in that the diphenyl halophosphate is diphenyl chlorophosphate, the diol is Bisphenol A, and the Lewis acid catalyst is magnesium dichloride. 9. An alkylene-arylene bridging group-containing bis(diphenyl phosphate) compound composition formed from the reaction of a diarylhalophosphate and an alkylene-arylene bridging group-containing diol under conditions in which by-product hydrogen halide is removed substantially concurrent with the course of the reaction in accordance with any of the processes of claims 1-8 and which contains more than 85% by weight of bisphosphate and less than 15%, by weight, of monophosphate by-products. 10. A composition according to claim 9, characterized in that the diol is Bisphenol A.

Inventors: BRIGHT DANIELLE A, PIRRELLI RONALD L, BRIGHT, DANIELLE, A., PIRRELLI, RONALD, L.
Applicants: AKZO NOBEL NV, AKZO NOBEL N.V.
Application year: 1997
Main classification: C07F9
IPC codes: C07F9