Organic compounds -- part of the class 532-570 series – Organic compounds – Four or more ring nitrogens in the bicyclo ring system
Patent
1992-02-19
1994-03-29
Shah, Mukund J.
Organic compounds -- part of the class 532-570 series
Organic compounds
Four or more ring nitrogens in the bicyclo ring system
544190, C07D25128
Patent
active
052986209
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a process for the reliable and quantitative destruction of cyanuric fluoride in the residues obtained during its preparation from cyanuric chloride and alkali metal fluorides in dipolar aprotic solvents.
It has been known for a long time that cyanuric fluoride can be prepared from cyanuric chloride using alkali metal fluorides, such as, for example, NaF (Tullock, Coffman, J. Org. Chem. 25, 2016 (1960) and European Patent 035,704) or KF or CsF (Japanese Patent 61,047,465) in dipolar aprotic solvents, such as, for example, sulfolane or benzonitrile, under anhydrous conditions. In this process, cyanuric fluoride is removed from the reaction mixture by distillation under normal pressure or in vacuo, if appropriate in the presence of an entraining agent. It serves as a useful precursor for agricultural chemicals, dyestuffs, optical brighteners, photochemicals and pharmaceuticals.
Industrial utilization of these processes has the great disadvantage that traces of cyanuric fluoride usually remain in the distillation residue, in addition to the alkali metal chloride formed, and that intermediate runnings containing cyanuric fluoride are obtained in the distillation of the cyanuric fluoride. Because of the high toxicity of cyanuric fluoride (LC.sub.50 (inhalation-rats): 3.1 ppm; LD.sub.50 (skin-rabbits): 160 ppm, J. Am. Ind. Hyg. Ass. 33, 382 (1972)), these residues therefore have to be detoxified before final disposal. Working up which may be carried out reusing the solvent, for example sulfolane, is likewise significantly easier and less expensive after destruction of the cyanuric fluoride, since the safety measures required for handling cyanuric fluoride can be dispensed with.
There was thus a need for a process in which not only the contents of HF which are present under certain circumstances, as in German Offenlegungsschrift 3,727,973 (=GB-A 2194238), are bonded, but in addition the residual cyanuric fluoride which still remains in the distillation residue or in distillation intermediate runnings can be reliably destroyed. Treatment of the distillation residues with milk of lime (Kuhn-Birett, Merkblatter Gefahrliche Arbeitsstoffe (leaflets on hazardous working materials), sheet no. C 73) is unsuitable for an industrial procedure, since after contamination with water the reaction vessels can be used again for the cyanuric fluoride preparation only after thorough cleaning--i.e. above all drying. The solvent must likewise be subjected to expensive drying before re-use.
It has now been found that the residual cyanuric fluoride which still remains in residues from the cyanuric fluoride preparation by reaction of cyanuric chloride with alkali metal fluorides in dipolar aprotic solvents after distillative removal of the majority of the cyanuric fluoride can be destroyed reliably and quantitatively by reacting the residue containing cyanuric fluoride with an alkali metal hydroxide, bicarbonate or carbonate which is anhydrous apart from any water of crystallization present, or any desired mixture of these compounds, in an amount which is at least equivalent to the residual cyanuric fluoride at temperatures of about 20.degree. to about 180.degree. C., preferably about 50.degree. to about 140.degree. C. and particularly preferably about 70.degree. to about 130.degree. C.
Possible alkali metal hydroxides, bicarbonates or carbonates are, for example, LiOH, NaOH, KOH, NaHCO.sub.3, KHCO.sub.3, Na.sub.2 CO.sub.3 or K.sub.2 CO.sub.3 or mixtures thereof.
If mixtures of alkali metal hydroxides, bicarbonates and carbonates are used, the components mentioned are used in the abovementioned amounts per mol of cyanuric fluoride in accordance with their proportion in the mixture.
The alkali metal compounds mentioned are added to the residues containing cyanuric fluoride either in bulk or in the form of a suspension of the alkali metal compound, preferably in the dipolar aprotic solvent used as the reaction medium, such as, for example, sulfolane, nitrobenzene or benzonitrile, or in another solvent which is ine
REFERENCES:
patent: 2937171 (1960-05-01), Smith
patent: 3162632 (1964-12-01), Olstowski
patent: 4329458 (1982-05-01), Klauke et al.
patent: 4332939 (1982-06-01), Seifert et al.
Seel et al. Chemische Berichte 92, 344, 1959.
Hoechst Aktiengesellschaft
Shah Mukund J.
Sripada P. K.
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