Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
2001-01-22
2002-04-02
Shippen, Michael L. (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
Reexamination Certificate
active
06365786
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an eco-friendly method of preparation of high purity tetrabromobisphenol-A.
BACKGROUND OF THE INVENTION
Tetrabromobisphenol-A, (CH
3
)
2
C(C
6
H
2
Br
2
OH)
2
(TBBPA, 79-94-7) is an -important substance among various bromo compounds. It is a bromo derivative of bisphenol-A (BPA). It is used as a flame retardant with over one-third of the total brominated flame-retardant because of high stability and suitability as an additive and reactive compound. TBBPA is also used in the preparation of acrylonitrile butadiene styrene (ABS) polymer as well as in the preparations of epoxy and polycarbonate resins. These resins in turn are widely used for the manufacture of electronic equipment, in particular of computer-printed circuit boards. The resins are also used as fire retardant in the manufacture of coatings, plastics, paints, adhesives and laminates as the high level activity of TBBPA allows it to be used at relatively low loading, translating to a greater retention of the physical properties of the base polymer.
BACKGROUND OF THE INVENTION
Reference may be made to K. Matsuda, M. Sugino and S. Kaji Japan, Kokai 74,108,003, Cl. 16 B21, Oct. 14, 1974 wherein TBBPA was prepared by reacting liquid bromine with BPA in methanol over three hours at 10-30° C. The solution was then kept at 44-45° C. for 3 h, treated with 383 ml of 98% H
2
SO
4
over 40 min at 20° C. and cooled to obtain the product. Nitrogen was-bubbled throughout to separate the by-product methyl bromide. The drawback is that it uses liquid bromine as brominating agent. Liquid bromine is a highly corrosive fuming liquid and air pollutant. Hence, it requires special equipment for its transport or storing and it needs safety measures. Thus, the method is convenient only to the bromine manufacturers. Besides these difficulties, only half of the total bromine used is utilized in the formation of product and the rest ends up as hydrobromic acid and methyl bromide as side products with the consumption of solvent which adversely affects the economics and also increases the number of unit operations. Moreover, the addition of concentrated sulfuric acid to the reaction vessel is hazardous as it is corrosive and liberates enormous heat due to dilution. Additionally, a cooling mechanism is required to absorb the heat evolved in the system, which unnecessarily enhances the product cost.
M. Ichimura, T. Nishiyama and K. Suzuki Japan Kokai 7654538, Cl. C07C25/18, May 13, 1976 prepared a high purity and less colored TBBPA by adding liquid bromine (43.68 Kg) to BPA (15.22 Kg) in tetra chloro ethylene (48 Kg) containing 0.2-1 times its weight water (66.7 Kg) at ≦40° C. over 1 h under stirring. About 99.1% TBBPA (36 Kg) was reported obtained on heating the mixture to ≧92° C. for 2 h with 99.6% purity. The drawback is that the liquid bromine requires special equipment to store or transport and safety measures as it is highly corrosive fuming liquid besides air pollutant. Also, it liberates hydrobromic acid as side product, which is not desired and has to be recycled with some more additional unit operations. Moreover, the heating of the reaction mixture to ≧92° C. for 2 h is energy intensive and thus increases the production cost.
D. R. Brackenridge U.S. Pat. No. 4,013,728, Cl. 260619A; C07 C37/00, Mar. 22, 1977 reported the preparation of TBBPA by adding the liquid bromine into BPA in 75-95% (w/w) aqueous acetic acid at 0-30° C. followed by heating to 80-120° C. for 5 to 60 min to give 92.3% product melting at 180-182° C. The drawbacks of this method are that both the liquid bromine and the solvent acetic acid are toxic and are air pollutants. The heating step after the addition of liquid bromine enhances the production cost. Additionally, hydrobromic acid is obtained as the byproduct, which has to be recovered from the solvent, and processed for its further use.
H. Jenkner and R. Strang Ger. Offen. 2,613,969, Cl. C07 C39/24, Oct. 6, 1977 reported a procedure for obtaining TBBPA. According to them, to a suspension of 171 parts by weight of BPA in 300 parts by volume of 1,1-dibromo ethane and 300 parts by volume of an aqueous solution containing 80 parts by weight of sodium bromate and 53 parts by weight of sodium bromide, liquid bromine (245 parts by weight) was added over 3 h at 28° C. under stirring to give 269 g TBBPA from the organic phase. The aqueous phase was restored to its original composition via an electrolytic process. The mother liquor from the initial preparation was added and the process was repeated without the need of an additional 1,1-dibromo ethane to give a total yield of 97% TBBPA. The drawback is that it uses 2 equivalents of liquid bromine, 1 equivalent of sodium bromide and 0.47 equivalents of sodium bromate as brominating agent. About 1.5 equivalents of bromine in the form of sodium bromide or hydrobromic acid remained unused in the reaction. Additionally this method requires an electrolytic treatment to the aqueous layer to restore to its original composition for reuse in the succeeding batches and requires special equipment and safety measures to store and transport the liquid bromine.
J. Swietoslawski, A. Silowiecki, A. Ratajczak, B. Nocon and Z. Baniak Ger. Offen. 2,718,997, Cl. C07 C39/24, Nov. 17, 1977 reported the preparation of TBBPA wherein 100 g of liquid bromine was added to a solution of 68.4 g BPA in 125 ml of methanol containing 11.1 ml of concentrated sulfuric acid over 30 min at 30-35° C. followed by 86 ml of 50% aqueous sodium chlorate over 45 min at 35-40° C. The solution is stirred for 2 h at 40-45° C. and cooled to 15° C. to obtain 148 g of TBBPA in 97% yield. The main drawbacks with this method are that both the liquid bromine and sodium chlorate are highly corrosive. Liquid bromine requires special equipment and safety measures to stop the air pollution and to avoid accidents. The use of non-bromo compound as an oxidizing agent to utilize the byproduct is an energy intensive step and it releases unwanted side product and further complicates the purification step.
W. Baumann, A. Block, I. Boehnke, J. Fiernow, H. Fischer, P. Franke E. Heynisch, D. Timm and H. Weber Ger. East DD 159,066, Cl. C07 C39/367, Feb. 16, 1983 and Ger East DD 211,781, Cl. C07 C39/367, Jul. 25, 1984 prepared TBBPA by the bromination of BPA with bromine liquid in methylene chloride and water medium. In this method, the organic layer was separated from the mother liquor and treated with 10% aqueous sodium hydroxide (Ger. East DD 159,066, Cl. C07 C39/367, Feb. 16, 1983) and distilled (Ger East DD 211,781, Cl. C07 C39/367, Jul. 25, 1984) to get solvent for the reuse. The drawback is that the handling of liquid bromine is hazardous as it is highly corrosive and air pollutant and also 50% of total bromine used is converted into hydrobromic acid, which increases the process steps and thus effects, the cost of production. The neutralization of hydrobromic acid existing in the organic layer with 10% sodium hydroxide and the electrolytic treatment of the aqueous layer for the reuse in succeeding batches are extra steps involved in addition to the problems associated with the corrosive liquid bromine.
I. Bohenke, U. Geyer and D. Timm German East DD 211,782, Cl. C07 C39/367, Jul. 25, 1984 brominated 175 g of BPA with 462 g of bromine in a mixture of 100 ml toluene, 200 ml methylene chloride and 600 ml water under stirring at 43° C. Methylene chloride (198 ml) was distilled and the product (398.5 g, m. p. 153-161° C.) was filtered from the remaining at 10° C. Apart from the use of liquid bromine, only 79.3% of TBBPA was obtained along with the products like di- (3.6%) and tri-bromo (17.1%) derivatives. The drawback is that it uses liquid bromine, which is corrosive and air pollutant and requires special equipment for storing and transporting. Hydrobromic acid is produced as an undesired byproduct by the consumption of 50% of the total bromine used in the operation and needs additional unit operations to recycle. Besides these problems, the yield of TBBPA is only 85% and is
Ghosh Pushpito Kumar
Jethva Ashok Dahyabhai
Mehta Aditya Shantilal
Misra Sudhindra Nath
Pandya Rajesh Popatlal
Abelman ,Frayne & Schwab
Council of Scientific and Industrial Research
Shippen Michael L.
LandOfFree
Eco-friendly method of preparation of high purity... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Eco-friendly method of preparation of high purity..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Eco-friendly method of preparation of high purity... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2866499