A method for producing a condensed phosphoric acid ester obtained from synthetic xylenol and a composition obtained by this method

Claims

1. A method for producing a condensed phosphoric acid ester from industrial coal tar xylenol, which consists in taking industrial coal tar xylenol, continuously pumping it from a storage tank into a separate drying unit, then bringing its moisture content to 0.01% by weight; then feeding the industrial coal tar xylenol dehydrated in the first stage into a weighing tank and loading the required amount into a reactor; then starting the stirrer, and loading 0.2-1.5% by weight of catalyst into this reactor, wherein the catalyst is loaded in the form of anhydrous powder or as a solution in anhydrous synthetic xylenol, and starting the process of heating the reactor to ~115°C; then adding phosphorus oxychloride to the reactor over a period of ~3 hours,for which phosphorus oxychloride is pumped from the storage tank into a separate tank for weighing; after weighing, 1 / 3 of the molar mass of technical coal xylenol of the required amount of phosphorus oxychloride is taken and pumped into the reactor, while in the process of adding phosphorus oxychloride, the reactor is slowly heated at a rate of 5-10 °C per hour until the temperature of the mixture rises to ~125 °C; while the gaseous hydrogen chloride released during the reaction in the reactor is continuously fed from the upper part of the reactor into the absorption unit, where it is absorbed by water; then, upon completion of the addition of 1 / 3 of the molar mass of xylenols of the required volume of phosphorus oxychloride, the temperature in the reactor is increased at the same rate and brought to ~200 °C; then, after completion of the evolution of gaseous hydrogen chloride,the pressure in the reactor is reduced to 25-30 mm Hg to remove residual HCl and complete the reaction; then a sample is taken from the crude reaction mixture for analysis for chlorine content until the target value for the total chlorine content of <0.02% is achieved; then, upon completion of the HCl purification process, the crude product is transferred to the feed tank of the distillation unit, while at this stage the crude reaction product consists of a mixture of the finished fire-resistant oil and technical coal tar xylenol, i.e. unreacted technical coal tar and the catalyst residue; then the crude reaction product is fed at a temperature of ~200 °C to the regeneration column of the distillation unit, which operates at a reduced pressure of 2-3 mbar and a temperature in the cube of ~205-230 °C, while the excess technical coal tar xylenol, which is the first distillate, is regenerated,then, the phosphates are pumped from the bottom of the regeneration column into the main distillation column, in which the phosphates of the fire-resistant oil are distilled from the top of the column at a pressure of 3-4 mbar and a temperature in the bottom at a temperature of ~265-285°C and the catalyst residues accumulating in the bottom of the main column are continuously removed, then, the distilled phosphates of the fire-resistant oil, leaving the top of the column in the form of condensate, are fed and fed into the steam stripping column, with a decrease in temperature to 160°C and there, at ~160°C, reducing the pressure to 25-60 mm Hg and raising the temperature in the bottom to 165-170°C, a further reduction in the content of free xylenol in the synthetic product is performed; Next, they cool and filter the stripped phosphate esters of fire-resistant oil from the Thermal Engineering Institute - OMTI, followed by pumping them into a sampling tank, from where samples of the resulting product are collected,which are sent to the quality control laboratory; then, if the parameters of the obtained target product - fire-resistant oil - are confirmed to comply, the synthesis process is stopped and the finished product is pumped into the finished product storage tank, and if the quality of the obtained product does not meet the technical requirements, a repeated distillation of the OMTI phosphates is performed, or by washing the OMTI phosphates with an alkali solution, namely, a repeated washing of the crude fire-resistant oil is performed after the vacuum distillation stage, from which the residues of acidic products are additionally removed, which is carried out by mixing the obtained raw fire-resistant oil with a 1-5 wt.% solution of sodium hydroxide NaOH, heated to 40-50 ° C, while the concentration of the sodium hydroxide solution is determined by the acid number of the crude oil, at which the volume of the sodium hydroxide solution should be equal to the volume of the purified fire-resistant oil, and,a sodium hydroxide solution is prepared using demineralized water, then the mixture of fire-resistant oil and sodium hydroxide solution is subjected to constant stirring for 2 hours; then, after a short period of settling for 30 minutes, the resulting aqueous-alkaline layer is separated, and the specified operation is repeated from three to eight times until the finished product - triaryl phosphate - is stabilized, i.e. until the transparency of the target product is stabilized; then the crude triaryl phosphate is sent to the washing columns to remove residual alkali, while washing is carried out counter-currently using demineralized water heated to 40-50 ° C until the reaction of the aqueous extract from the resulting target product triaryl phosphate becomes neutral, and the triaryl phosphate itself becomes transparent; then the resulting target triaryl phosphate is fed to a thermal vacuum dryer, during which the reactor with triaryl phosphate is heated to 50-60°C, while the process is carried out under a vacuum of 2-3 mm Hg,The said operation is carried out until the target product, triaryl phosphate, is completely free of moisture; then a sample of triaryl phosphate is taken to perform an analysis of the main qualitative technical characteristics, obtaining the finished target triaryl phosphate, wt.%:, 1-Phenol 20,0-40,0 Sum of m-+ p-cresyl phosphates 0,10-0,15 2-2,6-dimethylphenylphosphate 0,3-0,4 3-3,5-dimethylphenylphosphate 60,0-80,0 4-2,3-dimethylphenylphosphate 1,0-1,1 5-3,4-dimethylphenylphosphate 0,2-0,5 Total methyl ethyl phenyl phosphates 2,0-3,0 2. The composition of the fire-resistant oil of the condensed phosphoric acid ester, obtained by the method according to paragraph 1, containing, in wt.%: 1-Phenol 20,0-40,0 Sum of m-+ p-cresyl phosphates 0,10-0,15 2-2,6-dimethylphenylphosphate 0,3-0,4 3-3,5-dimethylphenylphosphate 60,0-80,0 4-2,3-dimethylphenylphosphate 1,0-1,1 5-3,4-dimethylphenylphosphate 0,2-0,5 Total methyl ethyl phenyl phosphates 2,0-3,0