Chemical process
AssigneeEthyl Corporation
InventorsWalter W. Lawrence, Jr., Tom W. McKay, Karl E. Wiegand
Life of this patent
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Abstract
It is disclosed that citric acid and salts thereof are readily produced by reacting acetone dicarboxyl ions, cyanide ions and alkali metal ions to produce an intermediate system which is subsequently reacted in an excess caustic system to form a salt of citric acid and that the salt is readily recovered by precipitation from the excess caustic system under proper conditions of concentration and temperature without requiring the formation of calcium salts. The recovered salt may be used directly or may be subjected to additional purification or may be converted to citric acid or other salts thereof by treatment with an acidification system such as sulfuric acid.
Claims31
A process for producing alkali metal salts of citric acid which comprises:
- A - forming a system of acetone dicarboxyl ions, cyanide ions and alkali metal ions in the proportions of about 1 mol equivalent cyanide ions and from about 1.5 to about 2.0 alkali metal atom equivalents per mol equivalent acetone dicarboxyl ions, and reacting said system for from about 0.1 to about 72 hours, at a temperature of from about 0.degree. to about 100.degree. C, and
- B - reacting the system from Step A with caustic in a solution containing from about 5 to about 40 percent by weight caustic of an alkali metal for from about 0.25 to about 8 hours at from about -10.degree. to about 180.degree. C.
A process for producing alkali metal salts of citric acid which comprises:
- A - reacting sodium cyanide, sodium hydroxide and acetone dicarboxylic acid in molar proportions of from about 1:0.5:1 to about 1:1:1 for from about 0.1 to about 72 hours at a temperature of from about 0.degree. to about 100.degree. C, and
- B - reacting the system from A with caustic in a solution containing from about 5 to about 40 percent by weight caustic of an alkali metal for from about 0.25 to about 8 hours at from about -10.degree. to about 180.degree. C.
A process for producing alkali metal salts of citric acid which comprises:
- A - forming a system of acetone dicarboxyl ions, cyanide ions and alkali metal ions in the proportions of about 1 mol equivalent cyanide ions and from about 1.5 to about 2.0 alkali metal atom equivalents per mol equivalent acetone dicarboxyl ions, and reacting said system for from about 5 seconds to about 15 minutes, at a temperature of from about 0.degree. to about 60.degree. C, and at a pH of from about 4 to about 6,
- A-1 - reacting the system from A at a temperature of from about 25.degree. to about 70.degree. C and which is at least about 5.degree. C different from that of Step A for a period of time of from about 0.1 to about 72 hours,
- B - reacting the system from Step A-1 with caustic in a solution containing from about 5 to about 40 percent by weight caustic for from about 0.25 hours to about 8 hours at from about 50.degree. to about 180.degree. C, and
- C - recovering trisodium citrate dihydrate from the system of Step B.
A process for producing alkali metal salts of citric acid which comprises:
- A - forming a system of acetone dicarboxyl ions, cyanide ions and alkali metal ions in the proportions of about 1 mol equivalent cyanide ions and from about 1.5 to about 2.0 alkali metal atom equivalents per mol equivalent acetone dicarboxyl ions, and reacting said system for from about 0.1 to about 72 hours, at a temperature of from about 0.degree. to about 100.degree. C,
- B - reacting the system from Step A with caustic in a solution containing from about 5 to about 40 percent by weight caustic, for from about 0.25 hour to about 8 hours at from about -10.degree. to about 180.degree. C forming a precipitate of trisodium citrate dihydrate,
- C - separating the precipitate produced in Step B producing a first mother liquor,
- D - combining the precipitate with water to form a solution thereof,
- E - combining said solution with caustic to form a system containing the trialkali metal salt of citric acid and an aqueous solution containing from about 5 to about 40 percent by weight of caustic,
- F - recovering the trialkali metal salt of citric acid as a precipitate from the system formed at Step E producing a second mother liquor, and
- G - recycling at least a part of at least one of the first and second mother liquors to at least one of Steps B and E.
Dependencies are inferred from the claim text.