Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
2000-09-07
2001-12-25
Keys, Rosalynd (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C568S633000, C568S643000, C568S645000, C568S646000
Reexamination Certificate
active
06333437
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method for purifying a specific bromine compound. More specifically, it relates to a method for purifying a specific bromine compound, which is capable of obtaining a bromine compound having high purity and excellent heat stability.
PRIOR ART
Generally speaking, a bromine compound typified by an ether derivative of tetrabromobisphenol A is widely used due to its excellent performance as a flame retardant for polyolefin-based resins and styrene-based resins.
Since the heat stability of the by-product is adversely affected when the bromine compound contains a certain type of a by-product produced during its production process, various means for purifying the bromine compound have been proposed heretofore.
For instance, JP-A 49-125348 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”) discloses a method comprising dissolving 2,2-bis[{3,5-dibromo-4-(2,3-dibromopropyloxy)}phenyl]propane (may be abbreviated as TBA-BE hereinafter) in a ketone-based solvent and cooling the mixture to deposit a bromine compound.
JP-A 55-111429 discloses a method of adding an aromatic hydrocarbon halide solution of TBA-BE to a mixture of methanol and seed crystals.
JP-A 4-234337 discloses a method comprising adding a poor solvent having a higher boiling point than a good solvent dropwise to a solution of TBA-BE dissolved in a good solvent and recovering the TBA-BE as fine powders while the good solvent is distilled out after the completion of the addition, and JP-A 7-316087 discloses a method comprising adding a solution of TBA-BE dissolved in a good solvent dropwise to a heated poor solvent having a higher boiling point than the good solvent while the solution was stirred and dispersing TBA-BE crystals into the poor solvent to recover them while the good solvent is distilled out.
JP-A 8-113547 discloses a method of adding a solution of TBA-BE dissolved in a good solvent to heated methanol in the presence of seed crystals while the good solvent was distilled out and crystallized to recover solids having large particle diameters.
JP-A 7-291884 discloses a method comprising adding water to an organic solvent solution of TBA-BE in the presence of a surfactant to form an emulsion and removing the organic solvent to recover TBA-BE powders.
JP-A 2-286645 discloses a method of adding unpurified TBA-BE to molten TBA-BE.
Further, JP-B 57-289 (the term “JP-B” as used herein means an “examined Japanese patent publication”) discloses a method comprising adding a poor solvent to a good solvent solution of TBA-BE and stirring the resulting solution with shearing force.
However, these methods require complicated operation or a large-scale apparatus, or the purity and heat stability of the obtained solid are not always satisfactory. Therefore, there has been desired a method for obtaining a bromine compound having higher purity and excellent heat stability with a simple apparatus.
SUMMARY OF THE INVENTION
The inventors of the present invention have conducted intensive studies to provide a purification method for obtaining a bromine compound having higher purity and excellent heat stability and have found that, in a method for purifying a bromine compound from a crude solution of a bromine compound, a bromine compound having high purity and excellent heat stability can be obtained by crystallizing the bromine compound while crystals contained in a slurry comprising a good solvent, a poor solvent and the crystals of the bromine compound are contained in a specific proportion and the solubility of the bromine compound in the solvents contained in the slurry falls within a certain predetermined range. The present invention has been accomplished by this finding.
That is, according to the present invention, there is provided a method for purifying a bromine compound by depositing the bromine compound represented by the following general formula (1) as solid particles from a crude solution containing the bromine compound:
wherein Ar
1
and Ar
2
are the same or different and each an aromatic hydrocarbon group having 6 to 10 carbon atoms; Y is an alkylene group having 1 to 3 carbon atoms, single bond, sulfone group or ketone group; R
1
and R
2
are the same or different and each a hydrocarbon group having 2 to 5 carbon atoms; m and n are the same or different and each an integer of 1 to 4; and p and q are the same or different and each an integer of 2 or 4,
wherein
(i) the crude solution is supplied into the slurry containing the particles of the bromine compound to deposit the bromine compound in the slurry under agitation;
(ii) the concentration of the particles of the bromine compound in the slurry is maintained at 10 to 50 wt %;
(iii) the solvent contained in the slurry is a mixed solvent of a good solvent and a poor solvent for a bromine compound and the solubility of the bromine compound in the mixed solvent is maintained at 0.1 to 5 g/100 g of solvent; and
(iv) the slurry is extracted to separate the solid particles of the bromine compound from the slurry.
According to the purification method of the present invention, when the obtained bromine compound is mixed with a flame retardant for resins, there will be obtained a high-purity bromine compound that neither reduces the heat stability of a resin nor causes the coloration of the resin. According to the purification method of the present invention, particularly when the bromine compound is mixed with a resin, impurities causing an adverse effect are separated into a mixed solvent, thereby making it possible to obtain a bromine compound of interest as a high-purity solid at a high yield. Further, the purification method of the present invention facilitates a continuous operation and can be carried out with a simple apparatus under mild conditions. Therefore, it is industrially advantageous.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1
shows an example of an apparatus for purifying a bromine compound in the present invention.
Numbers 1, 2 and 3 denote an input port, number 4 a capacitor, number 5 a thermometer, number 6 a pump, number 7 an input port for a recycled slurry, number 8 an output port for a slurry, number 9 a stirrer and number 10 a slurry.
The present invention will be described in detail hereinafter.
The bromine compound to be purified in the present invention is represented by the above general formula (1). In the above general formula (1), Ar
1
and Ar
2
are the same or different, and each an aromatic hydrocarbon group having 6 to 10 carbon atoms, as exemplified by benzene, monomethyl-substituted benzene, dimethyl-substituted benzene and naphthalene. Of these, benzene is preferred. Y is a bond or group for combining Ar
1
and Ar
2
, as exemplified by an alkylene group having 1 to 3 carbon atoms, single bond, sulfone group and ketone group. Of these, methylene group and isopropylidene group are preferred. R
1
and R
2
are the same or different and each a hydrocarbon group having 2 to 5 carbon atoms, as exemplified by ethyl group, propyl group, isopropyl group, butyl group and isobutyl group. Of these, an ethyl group and propyl group having 2 or 3 carbon atoms are preferred. m and n are the same or different, and each an integer of 1 to 4, preferably 1 or 2. p and q are the same or different, and each an integer of 2 or 4, preferably 2.
Illustrative examples of the bromine compound include 2,2-bis[{3,5-dibromo-4-(2,3-dibromopropyloxy)}phenyl]propane, 2,2-bis[{3,5-dibromo-4-(2,3-dibromo-2-methylpropyloxy)}phenyl]propane, bis[{3,5-dibromo-4-(2,3-dibromopropyloxy)}phenyl]methane, bis[{3,5-dibromo-4-(2,3-dibromo-2-methylpropyloxy)}phenyl]methane, bis[{3,5-dibromo-4-(2,3-dibromopropyloxy)}phenyl]sulfone, bis[{3,5-dibromo-4-(2,3-dibromo-2-methylpropyloxy)}phenyl]sulfone, {3,3′,5,5′-tetrabromo-4,4′-(2,3-dibromopropyloxy)}biphenyl, {3,3′,5,5-tetrabromo-4,4′-(2,3-dibromo-2-methylpropyl
Hoshimi Haruhisa
Mukai Akihiro
Sato Takahiro
Tahira Yasuhisa
Taketani Yutaka
Keys Rosalynd
Teijin Chemicals Ltd
LandOfFree
Method for purifying a bromine compound does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for purifying a bromine compound, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for purifying a bromine compound will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2591430