Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Patent
1995-03-23
1997-07-15
Dees, Jose G.
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
570204, 570190, 568672, 568699, 568868, 5483261, C07D23328, C07D23330
Patent
active
056484992
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a safe method of decomposing halogenated aromatic compounds such as polychlorinated biphenyl (hereinafter "PCB"), using chemical reaction of halogenated aromatic compounds in a polar solvent.
BACKGROUND ART
It is known that it is extremely difficult to treat PCB or other such halogenated aromatic compounds. This has led to considerable efforts directed toward the removal or decomposition of halogenated aromatic compounds. Methods for accomplishing this using a reaction process that takes place in the presence of an alkali include the alumina-alkali process disclosed by U.S. Pat. No. 2,951,804. U.S. Pat. No. 4,532,028 discloses a method of reacting alkali and a PCB content of up to 50,000 ppm in a mixture of alkyl or alkylene sulfoxide and polyol, thereby reducing the content to several ppm. Other examples include Canadian Pat. No. 1,181,771 which discloses a method employing melted sodium, and Italian Patent No. 22,215 which discloses a method using alkaline earth metal on which PEG is adsorbed.
Each method has its good points. However, with the prior art techniques it is not possible to further remove halogenated aromatic compounds from samples having a low concentration thereof, so that the halogenated aromatic compound content is further reduced to the extent that the inclusion thereof is substantially not recognizable; it is not yet possible to reduce the halogenated aromatic compound concentration to i ppm or below. Moreover, it is widely known that heating the solvent used in the prior art methods to a high temperature of 120.degree. C. or over in the presence of an alkali or alkali metal has a chemically destablizing effect that promotes solvent decomposition and polymerization, degrading the basic function of the solvent.
SUMMARY
The inventor of the present invention investigated various ways of eliminating such drawbacks and discovered a highly effective method of decomposing halogenated aromatic compounds. In accordance with the method, a heat-resistant alkaline polar solvent that has a high boiling point and good high-temperature stability with respect to alkalis is selected, in which halogenated aromatic compounds are treated, using an alkali.
Thus, in the method of the present invention for decomposing halogenated aromatic compounds, the halogenated-aromatic compounds are contacted with an alkali at a temperature ranging from about 100.degree. C. to about 300.degree. C., and resultant solid materials contained in the heat-resistant alkaline polar solvent are removed therefrom.
Here, the halogenated aromatic compound is PCB and analogous compounds thereof.
In the method of the present invention, there were found to be slight differences in the halogenated aromatic compound decomposing effect of the various heat-resistant alkaline polar solvents. It was confirmed that 1, 3-dimethyl-2-imizazolidinone (herein after "DMI"), sulfolane, and also a mixture of 1, 3-dimethyl-2-imidazolidinone and sulfolane, are heat-resistant alkaline polar solvents that are effective under all of the conditions. Here, sulfolane when heated excessively generates odor, degrading operationability. Thus, it is preferable to use DMI, or a mixture of DMI and other solvent.
Depending on the purpose, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, low alkyl-ethers of polyethylene glycol, trimethylene glycol, butylene glycol and low alkyl-ethers thereof are also effective. When the aim is to decompose halogenated aromatic compounds with high efficiency, it is preferable to use these solvents in an auxiliary role to make it easier to handle
Industrially these heat-resistant alkaline polar solvents are used relatively extensively and have low toxicity and risk. What should be noted is their outstanding ability to dissolve halogenated aromatic compounds. While, in a conventional method, it has been recognized that a reaction rate of a halogenated aromatic compound and an alkali becomes extremely low if only an extraction process is used, the remov
REFERENCES:
patent: 2951804 (1960-09-01), Juliard
patent: 4532028 (1985-07-01), Peterson
patent: 4910353 (1990-03-01), Siegman
Tanimoto Fumio
Yano Tsuneo
Dees Jos,e G.
Mitsui & Co. Ltd.
Neos Co., Ltd
Research Institute for Production Development
Williams Rosalynd
LandOfFree
Method of decomposing halogenated aromatic compounds 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 of decomposing halogenated aromatic compounds, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of decomposing halogenated aromatic compounds will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1493282