MXPA98005504A - Process for the purification of fosf oxyloride - Google Patents

Abstract

The present invention relates to the fact that impure POCl3 is purified by distillation in the presence of high-boiling nitrogen compounds selected from the group consisting of pyridines and substituted pyrimidines, aliphatic open-chain and cyclic amines, open-chain and cyclic amidines, guanidines and aromatic amines

Description

? PROCEDURE FOR THE PURIFICATION OF OXYCHLORIDE OF PHOSPHORUS FIELD OF INVENTION 5 The present invention relates to a process for the purification of doped phosphorus oxychloride (POCI3), which would lead to products with a high color index in the case of the manufacture of esters of phosphoric acid. Especially described are procedures for the purification of doped POCI3 which is formed as an accompanying product in the manufacture of chlorinated nitrogen heterocycles. fifteen DESCRIPTION OF THE PREVIOUS TECHNIQUE The production of chlorinated N-heterocycles, for example polychloropyrimidines, has been described by reaction of the corresponding polyhydroxypyrimidines with PCI5 or with PCI3 + CI2 in a large number of patent applications, for example in EP 697 406, WO 96 / 23776, EP 745 593 or EP 761 653. In this reaction we obtain, REF: 27808 in addition to the chlorinated heterocycles, also POCI3 as an accompanying product in amounts equivalent to the number of chlorine atoms introduced. The use of this POCI3 for other syntheses is absolutely necessary from the economic and ecological point of view. POCI3 is used in the chemical indy, among other things, as an intermediate product for obtaining aliphatic or aromatic phosphates. To be usable, for example as an auxiliary product in the synthetic materials or photographic indy, these phosphates mbe free of their own color. Depending on the corresponding method, for example, for the preparation of polychlorinated pyrimidines, the POCI 3 obtained in this case is so contaminated that it can not be used for the synthesis of esters of phosphoric acid that can be used without limit. For example, impurities with a similar boiling point containing carbon, chlorine, oxygen or nitrogen can be present in POCI3, separated by distillation. These impurities lead to the increase of the color index in the synthesis of phosphoric acid esters. Neither does a re-distillation of doped POCI3, even through columns effective, leads to a satisfactory elimination of impurities. Therefore, a method is required with which the quality of POCI3 can be improved in such a way that it can be used in an unlimited way to obtain phosphoric acid esters.

DETAILED DESCRIPTION OF THE INVENTION A method for the purification of characterized POCI3 has been found because the contaminated POCI3 is distilled in the presence of high-boiling nitrogenous compounds selected from the group consisting of substituted pyridines and pyrimidines, of the open-chain and cyclic aliphatic amines, of the to open chain and cyclic idinas, of guanidines and aromatic amines. Purification refers especially to POCI3 from the synthesis of chlorinated N-heterocycles. Nitrogen compounds which can be used according to the invention are those which have a sufficiently high boiling point and which do not present themselves as new impurities in the distillation of POCI3 in the distillation according to the invention or which only occur in a trace state. These are, according to the invention, nitrogenous compounds with a boiling point > 140 ° C, preferably > 170 ° C, particularly preferably > 200 ° C (all indications at normal pressure). For easy handling, the melting point should be at most 60 ° C, preferably at most 40 ° C. Examples which may be mentioned are: alkylpyridines or polyalkylated pyridines, such as 4-methylpyridine, 4-tert-butylpyridines, various dimethylpyridines with position isomers, trialkylated pyridines, such as, for example, 2,4,6-trimethylpyridine etc., substituted pyridines by aryl groups such as for example 2-, 3- or 4-phenylpyridine, the diphenylpyridines or triphenylpyridines with position isomers such as for example 2, 4, 6-triphenylpyridine etc., pyridines substituted by fused rings, such as for example quinoline, isoquinoline, acridine. These cited systems can be derived by means of other substituents. By way of example, quinaldine or p-hydroxyquinoline may be mentioned. In addition, derivatives of oligo- and polypyridine, for example 2,2'-bipyridyl, 3,3'-bipyridyl, 4,4'-bipyridyl, 2,4'-bipyridyl, 2,6-bis, can be used according to the invention. (2-pyridyl) -pyridine, etc. Other examples of pyridine derivatives according to the invention are pyridines substituted by amino groups, for example 4-aminopyridine, 4-dimethylaminopyridine, etc. It is also possible to use pyridine or oligo- or polypyridine derivatives substituted in a mixed manner by alkyl, aryl, amino or by condensed rings. Examples of other high-boiling nitrogenous compounds, which can be used according to the invention, are the pyrimidines, corresponding to the pyridines mentioned. Other examples are: aliphatic open-chain or cyclic amines, amidines or open-chain or cyclic guanidines, such as triocyt alamine, triisobu-tilamine, alkyiper idine, diaza-bicyclo-nonane (DBN), di az abi cycle -undecano (DBU), tetramethylguanidine and analogous nitrogen compounds with suitable boiling points. Finally, aromatic amines, such as aniline, N-methyl-aniline and the like, are suitable. According to the invention, a single nitrogenous compound or also a mixture of several of them can be used. Preferred nitrogen compounds are pyridine derivatives or open chain or cyclic amidines or guanidines.

According to the invention, when working discontinuously, the addition of nitrogenous compound to the doped POCI3 is less than 10% by weight, preferably less than 5% by weight, particularly preferably less than 1% by weight. Of course it is also possible to use more than 10%, it being possible to use or mix several times, in the case of the continuous or semicontinuous form, the nitrogenous compound of high boiling point as a distillation glue or to recirculate it. The distillation according to the invention can be carried out under elevated pressure, at low pressure or under normal pressure, with normal pressure being preferred. The process can be carried out discontinuously or continuously. The distillation according to the invention can be carried out in various forms of application. As an example, impure POCI3 can be introduced initially. The nitrogenous compound (s) according to the invention are then introduced under stirring: the purified POCI3 is then distilled off through a column. When using nitrogenous compounds in the boiling range of 140 to 200 ° C, it is advantageous to use a column effective to avoid nitrogen compounds in the distillation of POCI3. In the case of boiling points of the nitrogenous compounds, located above 200 ° C, less effective columns are sufficient. However, it is also possible to initially introduce the nitrogenous compound and then add the contaminated POCI3 and remove it by distillation of the mixture according to the invention. In this case, a larger amount of nitrogenous compound, for example 10% by weight or more, based on the amount of POCI 3, for example up to 50 or even up to 100% by weight, will be advantageously introduced initially. If, in this case, the POCI3 removed by distillation or by impurity is replaced in batches, the procedure may be carried out continuously, until the glue contains a quantity of impurities such that they pass into the distillate. The spent nitrogen compound will be disposed of properly, for example by incineration by treatment with exhaust gases. Finally, the doped POCI3 and the nitrogenous compound can be fed in proportions by weight selected, together or separately, in a distillation column that works continuously, removing the purified distillate as the overhead product and the nitrogenous compound in the manner of tail product. The glue product is recycled and fed again as a nitrogenous compound; a small part of the glue is removed, discarded and replaced by fresh nitrogen compound. In case of feeding separately, the nitrogenous compound will be preferably fed above the POCI3. The following examples show the process according to the invention, without limiting it to it.

EXAMPLE A Obtaining tricresyl phosphates (aromatic phosphates) from dß POCI3 for the determination of the color index.

A mixture consisting of 200 g of m-cresol, 80 g of p-cresol and 50 g of phenol is combined with 0.1 g of MgO and treated, with stirring, with 153.5 g of POCI3 to be tested. Then it is heated, under agitation, (HCl release) for 10 hours at an internal temperature of 330 to 340 ° C. It is then cooled slightly and distilled at 10 mbar. In the interval 230 to 270 ° C head temperature the product is released. This main stream is washed at 60 ° C twice with 100 ml, each time, of 0.1 N NaOH and twice with 100 ml of water. The wet phase of tricresyl phosphate is then dried at approximately 100 ° C under vacuum by water jet. The color index of the dry aromatic phosphate is determined.

Example B. Obtaining trichloropropylphosphate (aliphatic phosphate) from POCI3 for the determination of the Color Index Initially 153.5 g of POCI3 are introduced to be tested, and treated, at room temperature, with 0.8 g of TÍCI4. Then, 232 ml of propylene oxide are added dropwise over the course of 1 hour. The internal temperature is maintained at approximately 80 ° C by external cooling. It is then stirred for 1 hour at 80 ° C and finally a vacuum is applied by a water pump for the removal of the propylene oxide residues. It is then washed at 80 ° C, once, with 100 ml of 0.1 N HCl, once with 100 ml of water, once with 0.1 N NaOH and once with 100 ml of water. Finally, the vacuum is applied by a water pump at approximately 90 to 100 ° C for drying the product. The color index of the dry aliphatic phosphate is determined.

Example 1 We treated 153 g of a distillate of POCI3 from the production of dichloropyrimidines, which had, according to example A) a color index of 180 Hazen and, according to example B) a color index of 380 Hazen, with 1.0% in quinoline weight and boiled at reflux for 1 hour. Subsequently, 144 g of colorless distillate at normal pressure (head temperature at 106 ° C) were distilled off through a column with a length of 10 cm. The color index according to example B) was 40 Hazen, and according to example A) of 20 Hazen.

Example 2 The repetition of Example 1, with 1.0% by weight of quinaldine instead of quinoline provided 145 g of colorless distillate of POCI3 which, according to example B) gave a Hazen value as a color index.

Example 3 1,000 g of POCI3 from Example 1 were treated with 10 g of collidine and distilled through a packed column, with a length of 1 meter, at normal pressure (head temperature of approximately 105 ° C). 955 g of a colorless distillate were obtained. The determination of the color index according to example A) gave a value of 15 Hazen, and according to example B) it gave a value of 25 Hazen.

Examples from 4 to 6 We treated 153 g of a distillate of POCI3, from the production of dichloropyrimidines, which according to example B) had a value of 430 Hazen as a color index, respectively with 1.0% by weight of 4-phenylpyridine, 4-dimethylaminopyridine or , 2'-dipyridyl. After the distillation analogous to that of Example 1, in the determinations of the color index according to example B), values of Hazen, Hazen 30 and Hazen 45 were obtained.

Example 7 500 g of a distillate of POCI3 from the production of trichloropyrimidine was purified, which had, according to example B) a value of 280 Hazen as a color index, analogously to that of example 1, using 1.0% by weight of quinoline . After distillation the color index according to example B) reached a value of 20 Hazen.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention. Having described the invention as above, property is claimed as contained in the following:

Claims (7)

i CLAIMS

1. A process for the purification of POCI3, characterized in that it comprises distilling impure POCI3 in the presence of high boiling nitrogenous compounds chosen from the group comprising pyridines and substituted pyrimidines, aliphatic open-chain amines, and cyclics, open-chain amidines and cyclics, guanidines and aromatic amines.

2. The method according to claim 1, characterized in that a POCI3 that has been obtained as an accompanying product in the manufacture of chlorinated N-heterocycles.

3. The process according to claim 1, characterized in that the nitrogen-containing compounds have a boiling point higher than 20 140 ° C, at normal pressure.

4. The process according to claim 1, characterized in that the nitrogen-containing compounds are pyridine derivatives. 25

5. The process according to claim 1, characterized in that the nitrogenated compounds are amidines or open-chain or cyclic guanidines.

6. The process according to claim 1, characterized in that when the process is carried out batchwise or in batches, less than 10% by weight of nitrogen-containing compounds are used, based on the amount of POCI3 to be purified.

7. The process according to claim 1, characterized in that when the process is carried out continuously, from 10 to 100% by weight of nitrogen-containing compounds are used, based on the amount of POCI3 and the nitrogenous compounds are used for the purification of more POCI3 until it is depleted or recycled.