RU2028299C1 - Method for production of triarylphosphates - Google Patents

Abstract

FIELD: production of triarylphosphates. SUBSTANCE: product: mixture P(O)(OR)₃, where R is aryl. Reagent 1: POCl₃. Reagent 2: phenol-xylenol mixture at ratio of (30-40):(70-60) in terms of mass.%, with use of phenol-xylenol mixture in form of 3.5-xylenol of the synthetic and coal kinds in ratio of 2: 1. Reaction conditions: at 170 C with return of nonreacted phenol mixture to zone of reaction in the amount of 6-10 mas.% instead of fresh phenol-xylenol mixture. EFFECT: higher efficiency. 2 cl, 1 tbl

Description

 The invention relates to the synthesis of triaryl phosphates, which can be used as flame retardant turbine oils, plasticizers, additives to functional fluids, etc.

The traditional way to obtain triarylphosphates is a method consisting of reacting a mixture of phenols with a phosphorylating substance, which is most often phosphorus oxychloride (1). In the practice of many countries, both periodic and continuous methods for the production of triaryl phosphates on this basis are implemented (2). Moreover, the phosphorylation of phenols of coal origin (1) and synthetic alkylated phenols with an alkyl radical of C ₃ and higher, obtained by the Friedel-Crafts reaction, have certain differences. Synthetic alkylated phenols, as a rule, contain impurities of di- and polyalkylphenols present in the initial product of the Friedel-Crafts reaction. These substances have the least reactivity and practically do not interact with the phosphorylating agent. The least reactive phenols can be removed from the starting products by preliminary rectification, but this method is uneconomical. Therefore, in practice, after the accumulation of significant quantities of such products, it is customary to send them for burning.

 A known method for producing triaryl phosphates (3), which consists of the following stages: I - reaction of the interaction of phosphorylating substances with a recycled mixture of synthetic phenols, if necessary, in the presence of an additional mixture of phenols. In this case, the total molar ratio of phenols to phosphorus atoms of the phosphorylating agent is taken less than 3: 1, II - the reaction of the interaction of the product of stage I with the initial mixture of phenols, and the amount of this mixture added in stage II should be such that the total molar ratio of phenols introduced in the process, to the phosphorus atoms there was at least 3: 1, III - distillation of unreacted phenols from the product of stage II, which gives the above recyclable mixture of phenols, IV - from the recycling of the recyclable mixture to stage I.

The disadvantage of this method is its multi-stage and the use of high temperatures (200-280 ^about C) to achieve a high degree of conversion of the least reactive phenols. In addition, the method does not ensure the stability of the composition of the final product.

Closest to the proposed technical solution (prototype) is a method for producing triaryl phosphate used as a turbine oil (4), including the esterification of phosphorus oxychloride with coal xylene (GOST 11314-82), in the presence of a catalyst - titanium tetrachloride, followed by distillation of the crude ether and return mixtures of unreacted phenols containing di- and monochlorohydrides of arylphosphoric acids, boiling at 120-260 ^о С at a residual pressure of 45 mm Hg at the stage of esterification in the amount of 20 wt.% from the loaded xylene feed.

 The disadvantage of this process is the inability to achieve the yield of the target product of more than 70%, the unsatisfactory quality of the raw ether, the long process time and the instability of the composition and quality of the target product, which negatively affects the operational properties of turbine oil.

 The aim of the invention is to intensify the process and increase the yield of the target product while maintaining its operational properties.

The goal is achieved in that the esterification is carried out with a mixture of phosphorus oxychloride phenolic consisting of coal xylenol at a molar ratio of 1: (3-3,05) in the presence of titanium tetrachloride catalyst by stepwise heating the reaction mass to 170 ^{° C} followed by distillation of crude ester and returning the mixture of unreacted phenols to the esterification stage, wherein the phenol-xylene mixture (fx) with the mass ratio of phenol to xylene-mixture mixture (30-40): (70-60) is used as the phenolic mixture xylenols as a mixture of 3,5-xylenol using a synthetic coal and xylenol in a weight ratio of 2: 1, respectively, and / or a mixture of unreacted phenols extracted from the raw ester distillation in step c t.kip.90-130 ^C at a residual pressure of 20 -25 mmHg

 To obtain triaryl phosphates suitable as a flame-retardant hydraulic and lubricating fluid in the lubrication and regulation systems of turbine units, a recirculated mixture of unreacted phenols in the amount of 6-10 wt.% Is used, instead of the fresh phenol-xylene mixture.

 The difference of the proposed method from the known is the following.

 The use of a phenolic xylene mixture of a certain mass composition (30-40) :( 70-60), which helps to maintain the operational properties of turbine oil and saves scarce raw materials - coal xylene.

 Replacing scarce coal xylenol containing a large amount of non-reactive impurities with synthetic 3,5-xylenol in a certain mass ratio (1: 2) helps to achieve a deeper degree of phenol conversion at the esterification stage and to reduce the reaction time.

Return to the esterification step a mixture of unreacted phenols allocated to the distillation step in a more narrow temperature range of 90-130 ° ^C / 20-25 mmHg instead of 120-260 ° ^C / 45 mmHg, allows carrying out the reaction at a molar ratio phosphorus oxychloride: phenolic mixture = 1: (3-3,05), which in turn reduces the amount of return phenols (gr.12, table 1). In addition, the use of return phenols isolated in a narrower temperature range containing a significantly lower quality of arylphosphoric acid di- and monochlohydrides significantly improves the quality of return phenols (column 7.8, Table 2) and helps to increase the yield of the finished product.

 Recycling a mixture of unreacted phenols isolated in a selected temperature range in the amount of 6-10 wt.%, Provides a satisfactory quality of the raw ester and obtain the product used as turbine oil.

 These differences are new, not described in the scientific, technical and patent documentation and provide a new property, namely: increasing the degree of conversion of phenols to 93 (instead of 76% of the prototype) and reducing the reaction time by 1.7 times. Therefore, these differences meet the criterion of "Significant differences".

 The invention is as follows.

 PRI me R 1. The synthesis is carried out while loading the components in a reactor equipped with a stirrer, a thermometer, a reflux condenser connected to a hydrogen chloride absorption system. During the reaction, the temperature-time regime shown in Table 1 was used.

 Then, hydrogen chloride was blown off with nitrogen for 1 h.

 The fresh phenol-xylenol mixture had a mass ratio of phenol: 3.5 - xylenol synt.: Xylenol coal = = 40:40:20.

For cooking were used:
Synthetic phenol TU 6-09-5303-86 with a phenol content of 99.97%; Synthetic 3,5-xylenol TU 14-6-87-72 with a content of 3,5-xylenol 99.5%; state standard specification 11314-82 grade B coal-containing xylenol with a content of 3,5-xylenol 65-75%, neutral oils and bases 1%, water 0.3%, the rest - 2,4-xylenol, phenol, o-cresol and others impurities of a phenolic nature.

 In the table. 2 shows the recipe, synthesis conditions and properties of the raw ether and the finished product.

 PRI me R s 2,3,4. The synthesis is carried out analogously to example 1, with the difference that the fresh FCC has the following mass ratios of phenol: xylenols = 30:70 (example 2) = 28:72 (example 3) = 46:54 (example 4). As xylenols, a mixture of synthetic 3,5-xylenol and coal is used in a ratio of 2: 1, respectively. The ratio of reagents phosphorus oxychloride: FCC = 1: 3,00 in example 2, and = 1: 3,05 in examples 3 and 4, i.e. analogously to example 1 (see table 1).

 PRI me R 5. The process is carried out analogously to example 1, with the difference that the original FCC is a mixture of fresh FCC with a ratio of phenol: xylenols, similar to example 1, and the return phenolic fraction obtained by distillation in ether 1 cheese, in an amount of 20 wt. % in relation to fresh FCC (in the form of excess). The ratio of reagents phosphorus oxychloride: FCC = 1: 3.2.

 PRI me R 6. The process is carried out analogously to example 1, only use the return phenolic fraction obtained after distillation of the crude ether according to example 1, in the amount of 10 wt.%, Instead of fresh FKS. (First use of return phenols).

 PRI me R 7. The process is carried out analogously to example 6, only use the return phenolic fraction obtained after distillation of the crude ether according to example 6. (Second use of return phenols).

 PRI me R 8. The process is carried out analogously to example 7, only use the return phenolic fraction obtained after distillation of the crude ether in example 7. (Third use of return phenols).

(1) где n - число рециклов;
С_n - допустимое суммарное содержание нереакционноспособных нейтральных и кислых примесей в рециклизуемой фракции, мас.%;
С_о - содержание примесей нефенольного характера, а также пространственно-затрудненных малореакционноспособных фенолов, вносимых со свежей ФКС, мас.%. Рассчитываются по характеристике исходного фенольного сырья.Since the return phenols are enriched with impurities of a neutral, low reactivity, and acidic nature compared to the initial FCC, the number of recycles, taking into account the above factors, is determined by the formula (1)
n =

(1) where n is the number of recycles;
With _n - the permissible total content of non-reactive neutral and acidic impurities in the recycled fraction, wt.%;
With _about - the content of non-phenolic impurities, as well as spatially-hindered low reactivity phenols introduced with fresh FCC, wt.%. They are calculated according to the characteristics of the initial phenolic feedstock.

With _to - the content of acidic impurities in the return phenolic fraction obtained after distillation of the crude ether, wt.%.

With _f - the content of phosphates in the return fraction, wt.%.

 N is the amount of recycled fraction, parts by weight

 The amount of recycled phenol return fraction - 6-10 wt.% - corresponds to an excess of fresh FCC - 0.05 moles (over stoichiometry) (examples 3,4,6-8). As can be seen from example 5, an increase in the excess of FCC to 0.2 moles leads to an increase in the amount of unreacted phenols in the crude ether and, accordingly, to an increase in the amount of recycled phenol return fraction. Columns 10-12 in Table 2 are given to illustrate the characteristics of the raw ether in accordance with the requirements for the raw ether.

 PRI me R s 9.10. The process is carried out analogously to example 1. In this case, the ratio of reagents phosphorus oxychloride: FCC corresponds to 1: 3.05 and the return phenolic fraction is added instead of a portion of fresh FCC, and not as an excess.

 PRI me R 11. The process is carried out similarly to examples 9,10, while only the fraction of the return phenols is used as the initial FCC.

 PRI me R 12. The process is carried out analogously to example 1, but the ratio of the reactants phosphorus oxychloride: FCC corresponds to 1: 2.95, while the number of arylphosphoric acid chlorides increases and, accordingly, the yield of distilled TAF decreases.

 PRI me R 13. The process is carried out analogously to example 2, with the difference that instead of 6 wt.% Fresh FKS use the return phenolic fraction.

 PRI me R s 14,15,16,17. Carried out in a known manner according to the regulations.

 As can be seen from the table. 2, the described method allows to intensify the process, increase the degree of conversion of phenol-xylenol feed to 93%, reduce the feed rate due to the ability to operate return phenols without recycling them in excess, to obtain the target product with satisfactory quality. Repeated use of return phenols does not affect the quality of the raw ether (Project 6-8 of Table 2). The resulting triaryl phosphates can be used as plasticizers for PVC and as additives to functional fluids.

Claims (2)

1. METHOD FOR PRODUCING TRIARYLPHOSPHATES by esterification of phosphorus oxychloride with a phenolic mixture containing coal xylenol, with a molar ratio of reactants 1: (3 - 3.05) in the presence of a catalyst - titanium tetrachloride, with stepwise heating of the reaction mixture to 170 ^o С followed by distillation of the obtained ether - raw and by recirculating a mixture of unreacted phenols to the esterification stage, characterized in that either a phenol-xylene mixture is used as a phenolic mixture at a ratio of phenol to xyleneol mixture 30 - 40: 70 - 60 wt.%, Moreover, synthetic xylenol and coal xylenol in a mass ratio of 2: 1 respectively and / or a mixture of unreacted phenols isolated from crude ether at the distillation stage with a boiling point are used as a mixture of xylenols; 90 - 130 ^o With a residual pressure of 20 - 25 mm Hg  2. The method according to claim 1, characterized in that use a recycled mixture of unreacted phenols in an amount of 6 to 10 wt.% Instead of fresh phenol-xylenol mixture.

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