Preparation of cyanuric acid
AssigneeOlin Corporation
InventorsJohn A. Wojtowicz, Douglas A. Farmer, Jr.
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Abstract
A highly pure cyanuric acid produced by pyrolyzing a nitrogenous containing material capable of yielding cyanuric acid, such as urea, in an alkyl dinitrile solvent such as adiponitrile, at elevated temperatures, is disclosed. The overall process converts substantially all of the urea to cyanuric acid and cyanuric acid derivatives which are capable of being converted into trichloroisocyanuric acid and similar compounds, while allowing substantially complete recovery of the nitrile solvent for reuse.
Claims23
In a process for making cyanuric acid by pyrolyzing a nitrogenous containing material capable of yielding a cyanuric acid product, said material being dissolved in an inert solvent in a pyrolysis vessel to produce a hot reaction mass comprising a slurry of crude cyanuric acid in said solvent, characterized by the improvement which comprises employing as said solvent a linear alkyl dinitrile of the general formula:
- N.tbd.C(CH.sub.2).sub.n C.tbd.N
- wherein n ranges from 1 to 8.
A process for making cyanuric acid comprising:
- pyrolyzing in a pyrolysis vessel at a temperature of about 200.degree. C. to 250.degree. C., a solution of urea in adiponitrile to produce a slurry of crude cyanuric acid in adiponitrile;
- removing said slurry from said vessel and filtering said slurry to produce a cyanuric acid filter cake and an adiponitrile filtrate;
- returning said adiponitrile to said pyrolysis vessel and washing said filter cake to remove soluble impurities whereby a purified cyanuric acid product is obtained.
A process for making cyanuric acid comprising:
- pyrolyzing in a pyrolysis vessel at a temperature of about 200.degree. C. to 250.degree. C., a solution of urea in adiponitrile to produce a slurry of crude cyanuric acid in adiponitrile;
- removing said slurry from said vessel and quenching it in room temperature water;
- filtering said quenched slurry to remove said cyanuric acid as a filter cake from a separable mixture of water and a first adiponitrile filtrate;
- separating said water from said adiponitrile and evaporating said water to produce a pot residue of cyanuric acid and adiponitrile;
- filtering said pot residue to recover said cyanuric acid from said adiponitrile, said adiponitrile being admixed with said first adiponitrile filtrate;
- distilling said combined filtrates to produce a purified adiponitrile to be returned to the pyrolysis vessel;
- and
- combining said recovered cyanuric acid residue with said filter cake and washing said combination to remove soluble impurities whereby a purified cyanuric acid product is obtained.
A process for making cyanuric acid comprising:
- pyrolyzing in a pyrolysis vessel at a temperature of about 200.degree. C. to 250.degree. C., a solution of urea in adiponitrile to produce a slurry of crude cyanuric acid in adiponitrile;
- removing said slurry and distilling it to remove said adiponitrile and leave a crude cyanuric acid as a pot residue;
- washing said pot residue to remove impurities with a solvent whereby a purified cyanuric acid product is obtained.
Dependencies are inferred from the claim text.