Organic compounds -- part of the class 532-570 series – Organic compounds – Phosphorus esters
Reexamination Certificate
2000-01-05
2001-04-03
Ambrose, Michael G. (Department: 1626)
Organic compounds -- part of the class 532-570 series
Organic compounds
Phosphorus esters
C558S094000, C558S203000
Reexamination Certificate
active
06211396
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a process for producing a halogen-containing phosphate ester which is produced in various areas such as chemical and pharmaceutical industries. More specifically, the present invention relates to a clean process for producing a halogen-containing phosphate ester in which deleterious waste water generated during production of the halogen-containing phosphate ester is cleaned.
BACKGROUND ART
Halogen-containing phosphate esters are compounds widely used in various areas including chemical and pharmaceutical industries as resin additives such as flame retardants and plasticizers, intermediates for medicaments or pesticides and the like. When those halogen-containing phosphate esters which are solid at room temperature, among others, are produced, the products are effectively purified by the crystallization processes used to increase the quality of the products. However, when phosphate esters are produced by using crystallization processes, waste water which contains phosphorus-containing organic pollutants is generally generated.
Waste water from chemical plants and organic sewage such as drainage generally contain COD materials and phosphorus. The COD material refers to any organic material which indicates certain COD (i.e., chemical oxygen demand) in an aqueous solution. Since phosphorus has a considerable effect on the environment, effective removal of phosphorus from the waste water or organic sewage is important. Biological treatment or biodegradation has been known as one of the treatment methods for the waste water and organic sewage. Japanese Laid-open Patent Publications (Kokai) Nos. 7-275891 and 8-24872 describe processes in which phosphorus-containing waste water is biologically treated in an activated sludge treatment device to remove phosphorus from the waste water.
However, it has been difficult to effectively remove phosphorus-containing organic pollutants which are generated during production of halogen-containing phosphate esters, from the waste water, by conventional biodegradation. One of the reasons for such difficulty is that the pollutants contained in the waste water from the process for producing a halogen-containing phosphate ester, unlike the waste water from a process for producing a halogen-free phosphate ester, may include halogenated organic phosphorus in addition to inorganic phosphorus. Moreover, in the case that the waste water contains additional materials such as catalyst residue and unreacted raw materials, the biodegradation is expected to become more difficult. Furthermore, such waste water may adversely affect the natural environment as well as health of neighborhood and workers dealing with the treatment. In addition, devices for the biodegradation are generally those of a very large scale which are difficult to control. Moreover, treatment of the sludge involved in the biodegradation requires high cost.
The objective of the present invention is to provide a clean and safe process for producing a halogen-containing phosphate ester without generating deleterious materials, in which pollutants, especially phosphorus, are removed from waste water generated during production of the halogen-containing phosphate ester.
DISCLOSURE OF INVENTION
In order to address the above-mentioned difficulties, the present inventors have applied a distillation procedure to the process for producing a halogen-containing phosphate ester, which includes purification by crystallization. By the use of the distillation, water is removed from an aqueous solution which contains impurities in ppm levels, so that the impurities are left as a residue and removed. Hitherto, those skilled in the art have not considered such distillation to be practical for industrial use in view of its cost and efficiency. However, the present inventors have found that organic pollutants, especially phosphorus, can be easily, effectively and almost completely removed from the waste water generated during production of a halogen-containing phosphate ester at low cost by applying the distillation procedure to the production process.
According to one aspect of the present invention, the process for producing a halogen-containing phosphate ester includes the steps of (i) reacting a phosphorus halide selected from the group consisting of phosphorus oxyhalides and phosphorus pentahalides with a halogen-containing hydroxy compound to obtain a reaction mixture including a halogen-containing phosphate ester, (ii) purifying the halogen-containing phosphate ester by adding an aqueous medium selected from the group consisting of water, neutral aqueous solutions, acidic aqueous solutions and basic aqueous solution to the reaction mixture to crystallize the halogen-containing phosphate ester, and (iii) distilling waste water from the purifying step.
In one embodiment of the invention, the melting point of the halogen-containing phosphate ester may be about 30° C. or more. The melting point of the halogen-containing phosphate ester may be preferably about 90° C. or more.
In another embodiment of the invention, the halogen-containing hydroxy compound may be a halogenated aliphatic hydroxy compound. The halogenated aliphatic hydroxy compound may be a brominated neopentyl alcohol. The brominated neopentyl alcohol may be tribromoneopentyl alcohol.
In still another embodiment of the invention, the halogen-containing phosphate ester is tris(tribromoneopentyl) phosphate.
In still another embodiment of the invention, about 0.001 to about 20 parts by weight of the aqueous medium is added to 100 parts by weight of the reaction mixture in the purification step.
In still another embodiment of the invention, prior to the step of distillation, the waste water from the purification step is subjected to separation from the halogen-containing phosphate ester by the use of a continuous centrifugal device.
In still another embodiment of the invention, the step of distillation is carried out in a continuous manner.
According to another aspect of the present invention, the process for treating waste water generated during production of a halogen-containing phosphate ester indicates the step of distilling the waste water generated during purification of a halogen-containing phosphate ester by crystallization in which an aqueous medium selected from the group consisting of water, neutral aqueous solutions, acidic aqueous solutions and basic aqueous solutions is added to a reaction mixture including the halogen-containing phosphate ester, wherein the reaction mixture is obtained by reacting a phosphorus halide selected from the group consisting of phosphorus oxyhalides and phosphorus pentahalides with a halogen-containing hydroxy compound.
Thus, the invention described herein makes possible the advantages of (1) providing a clean and safe process for producing a halogen-containing phosphate ester substantially without generating deleterious material, in which the pollutants, especially phosphorus, are removed from deleterious waste water generated during production of the halogen-containing phosphate ester.
These and other advantages of the present invention will become apparent to those skilled in the art upon reading and understanding the following detailed description.
BEST MODE FOR CARRYING OUT THE INVENTION
A halogen-containing phosphate ester produced by the process of the present invention is purified by crystallization as described below. Thus, the process of the present invention is preferably applied to production of a halogen-containing phosphate ester which is solid at room temperature. The melting point of the halogen-containing phosphate ester is preferably about 30° C. or more, more preferably about 90° C. or more, and most preferably about 120° C. or more.
Examples of the halogen-containing phosphate ester, which is solid at room temperature, produced by the process according to the present invention include, for example, tris(halogenated aliphatic) phosphates such as tris(bromoneopentyl) phosphate, tris(dibromoneopentyl) phosphate, tris(tribromoneopentyl) phosphate
Ambrose Michael G.
Daihachi Chemical Industry Co. Ltd.
Fish & Neave
Haley Jr. James F.
Shin Elinor K.
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