Organic compounds -- part of the class 532-570 series – Organic compounds – Phosphorus esters
Reexamination Certificate
2001-07-06
2002-08-20
Powers, Fiona T. (Department: 1626)
Organic compounds -- part of the class 532-570 series
Organic compounds
Phosphorus esters
C558S070000, C558S156000, C558S096000
Reexamination Certificate
active
06437164
ABSTRACT:
TECHNICAL FIELD
With the effects of preventing oxidation and coloring of organic polymer materials during forming processes, improving weatherability and the like, biphenylenediphosphonite compounds contribute to the addition of high value to organic polymer materials, and their usefulness has been considered to be significant. The present invention relates to a method for producing a phosphonite compound containing phosphinobiphenylene of the formula (I′):
wherein R is a hydrogen atom or methyl and R
1
and R
2
are each a hydrogen atom or alkyl having 1 to 5 carbon atoms [hereinafter to be also referred to as phosphinobiphenylene of the formula (I′)], which is useful as a stabilizer of organic polymer materials, and to a method for preventing thermal decomposition of the phosphonite compound when heating a solution containing the phosphonite compound.
BACKGROUND ART
There are conventionally known methods for producing a phosphonite compound containing phosphinobiphenylene of the formula (I′), such as (A) a method including forming a complex with aluminum chloride from a reaction product of aluminum chloride, biphenyl and phosphorus trichloride, by the use of phosphorus oxychloride as a complex forming agent, subjecting this complex to filtration and removal, thereby to isolate halogenated phosphine, and subsequently reacting this compound with a phenol compound, such as 2,4-di-tert-butylphenol and the like, in the presence of triethylamine (JP-B-50-35096), (B) a method including removing excess phosphorus trichloride from a reaction product of aluminum chloride, biphenyl and phosphorus trichloride and adding dropwise the obtained halogenated phosphine-aluminum chloride complex to a mixture of pyridine and the aforementioned phenol compound to allow reaction (JP-A-2-270892), (C) a method including reaction of phosphorous acid-bis(2,4-di-tert-butylphenyl)ester-chloride with a Grignard compound obtained from 4,4′-dihalobiphenyl and magnesium (JP-A-2-221290) and (D) a method including adding ethers, such as diethyl ether and the like, as a complex forming agent to a reaction product of biphenyl and phosphorus trichloride in the presence of aluminum chloride, and reacting the obtained mixture with 2,4-di-tert-butyl-5-methylphenol and the like in the presence of a deacidifying agent (JP-A-8-253491) and the like.
In the production method of the aforementioned (A), it is necessary to use phosphorus oxychloride as a complex forming agent to isolate halogenated phosphine, and to filtrate and separate the generated phosphorus oxychloride-aluminum chloride complex. However, this complex has hygroscopicity, and in addition, shows filtration property that is not necessarily fine. Combined with the difficulty in recovering phosphorus oxychloride from this complex and problems both in the aspects of method and cost, this method is not an industrially beneficial production method. Moreover, since halogenated phosphine is designated as a mutagenic compound in Industrial Safety and Health Law, the operation for isolation is problematic in view of the safety to human body.
According to the production method of the aforementioned (B), phosphorus trichloride is distilled away, without forming a complex, in the presence of aluminum chloride, which leads to a defect in that polyphosphine chloride is generated as the reaction proceeds. As a result, the composition of the objective phosphonite compound varies depending on the conditions of distillation. The reaction concentrate becomes a glass-like compound having a very high viscosity at normal temperature, which can afford sufficient flowability for dropwise addition only upon heating. According to this method, moreover, heat generation during forming of a complex of pyridine and aluminum chloride in the first phase and that during deacidifying reaction by pyridine in the second phase occur at the same time. For a large-scale production, therefore, facility such as a large-sized cooling system and the like is required, which makes this method unbeneficial for industrial production in view of the operability and facility cost. Furthermore, filtration at a low temperature of −10° C. to remove a complex of pyridine and aluminum chloride remaining in the reaction product after separation of the complex is disclosed. The complex of pyridine and aluminum chloride is a hygroscopic and viscous substance, which is extremely difficult to apply to industrial filtration. As described in JP-A-5-230282, insufficient removal of aluminum chloride leads to easy hydrolysis of the objective compound, which is a fatal defect.
According to the production method of the aforementioned (C), the use of 4,4′-dihalobiphenyl containing polychloride biphenyl (PCB) as a starting material poses a serious problem. Moreover, production of Grignard compound requires a large amount of tetrahydrofuran solvent, while requiring separate and selective production of phosphorous acid-bis(2,4-di-tert-butylphenyl)ester-chloride under the conditions free of generation of phosphorous acid-tris(2,4-di-tert-butylphenyl)ester. In view of such defects, this method is not satisfactory.
According to the production method of the aforementioned (D), separation for recovery of ether as a complex forming agent and a deacidifying agent requires a lot of time and labor. Thus, this method is not industrially beneficial.
The products obtained by any of the aforementioned production methods (A)-(D) contain comparatively large amounts of unreacted phenol compounds, such as 2,4-di-tert-butyl-5-methylphenol, 2,4-di-tert-butylphenol compound and the like, which causes time-course coloring, degradation of properties (lower stabilizing action) and the like of the product. Ultimate removal of unreacted phenol compound by distillation may be one solution, but removal of unreacted phenol compound by distillation requires heating to 150° C. or above under reduced pressure, which in turn causes partial decomposition of the objective phosphonite compound during distillation. Therefore, there is a demand on a method for obtaining the objective product free of unreacted phenol compounds as impurities, which does not cause thermal decomposition of the objective phosphonite compound.
The present invention has been made in view of the above-mentioned situation, and aims at providing a method by which a high quality phosphonite compound containing phosphinobiphenylene of the aforementioned formula (I′) can be produced safely and in high yields, as well as a method for preventing thermal decomposition of the phosphonite compound when heating a solution containing the phosphonite compound.
DISCLOSURE OF THE INVENTION
The present inventors have conducted intensive studies in an attempt to solve the above-mentioned problems and arrived at the following findings (i)-(iv).
(i) When biphenyl and excess phosphorus trichloride are reacted in the presence of aluminum chloride and pyridines are added to the resulting reaction product to form a pyridine-aluminum chloride complex, after which the mixture is heated (for example, heating to 60-100° C.) to distill away the excess phosphorus trichloride, phosphorus trichloride can be distilled away efficiently and the residual amount of phosphorus trichloride can be made extremely small, because the viscosity of the reaction product can be lowered (improved flowability of reaction product) due to the addition of pyridines and heating. Moreover, since aluminum chloride is deactivated by the formation of the complex, the production of polyphosphine chloride, which occurs as the reaction proceeds, can be suppressed when phosphorus trichloride is distilled away.
(ii) When, for example, a phenol compound, such as 2,4-di-tert-butylphenol, 2,4-di-tert-butyl-5-methylphenol, 2,4-di-tert-butyl-6-methylphenol and the like, is added to the reaction product, from which the above-mentioned phosphorus trichloride has been distilled away, and then a base comprising amine such as pyridine and the like is added dropwise as a deacidifying agent to synthesiz
Kasagi Masahiro
Mishima Akio
Ozaki Yoshihiro
Yamamoto Masataka
Yokomatsu Takashi
Powers Fiona T.
Yoshitomi Fine Chemicals, Ltd.
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