Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
2000-06-09
2001-11-06
Richter, Johann (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C568S347000, C568S363000, C568S364000
Reexamination Certificate
active
06313352
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention provides a process for producing canthaxanthin by mixing &bgr;-carotene with an alkali metal chlorate or an alkali metal bromate in water and an organic solvent immiscible with water; adding an iodine halide or iodine; and adding a metal iodide whereby the &bgr;-carotene is oxidized to yield canthaxanthin.
2. Related Art of the Invention
Canthaxanthin, a natural colorant, is used as a food dye and as an additive for animal feeds. A process for producing canthaxanthin is disclosed, for example, in U.S. Pat. No. 4,212,827. In this process &bgr;-carotene is oxidized with sodium chlorate or sodium bromate in the presence of iodine, bromine, selenium dioxide, vanadium pentaoxide or osmium tetraoxide as a catalyst.
However, in this production process the time necessary for the reaction is from 1 to 250 hours. Furthermore, in order to obtain canthaxanthin with an optimal yield in an advantageous embodiment, at least 20 hours are required (see column 2, lines 33 to 36 of U.S. Pat. No. 4,212,827). Thus, it is recommended that the reaction is conducted for a long time. As an example in which the reaction time is relatively short, Example 12 in the same United States Patent discloses a process for producing canthaxanthin in which 0.00075 mole of sulfuric acid in 20 ml of water is added dropwise continuously over 2 hours at a temperature of 30° C. into a suspension of 10 g of all-trans-&bgr;-carotene in 250 ml of chloroform and an aqueous solution containing 20 g of sodium chlorate and 0.4 g of sodium iodide. The reaction is conducted at the same temperature for 3-4 hours. However, if the reaction mixture becomes strongly acidic in the process of the same Example, the resultant product can decompose. Therefore, this process requires that the addition of sulfuric acid is gradually and carefully performed over a long time.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a process for producing canthaxanthin by oxidizing &bgr;-carotene with sodium chlorate or sodium bromate for a short time, with efficiency and in an industrially advantageous manner.
The object of the present invention can be achieved by a process described below.
That is, the present invention provides a process for producing canthaxanthin comprising the steps of:
a) mixing &bgr;-carotene with an alkali metal chlorate or an alkali metal bromate in water and an organic solvent immiscible with water;
b) adding an iodine halide or iodide; and
c) adding a metal iodide.
DETAILED DESCRIPTION OF THE INVENTION
Examples of iodine halide used in the present invention include iodine chloride, iodine trichloride, iodine bromide, and iodine tribromide. The iodine halide may be used in one or more species. The iodine halide and iodine may be used together.
It is preferred to use iodine in step b).
The amount of the iodine halide or iodine, the total amount of the iodine halide and iodine if the two are used together, is preferably from 1 to 20% and more preferably from 3 to 15% per mole of &bgr;-carotene, including 2, 4, 5, 7, 9, 10, 12, 14, 16, 18, 19 and all values and subranges there between.
Examples of a metal iodide used in step c) include lithium iodide, sodium iodide, potassium iodide, magnesium iodide, calcium iodide, silver iodide, copper (I) iodide and copper (II) iodide. It is preferred to use an alkali metal iodide in step c). The metal iodide may be used in one or more species.
The amount of the metal iodide is preferably from 1 to 40% and more preferably from 5 to 30% per mole of &bgr;-carotene, including 2, 4, 6, 8, 10, 11, 13, 15, 18, 21, 24, 27, 29, 32, 35, 37, 39 and all values and subranges there between.
In order to produce canthaxanthin efficiently for a short time in the present invention, the molar ratio of the metal iodide to iodine halide or iodine is preferably from 0.5 to 10, and more preferably from 2 to 5, including 1, 1.5, 3, 4, 6, 7, 8, 9.5 and all values and subranges there between.
In the present invention, the combined use of iodine halide or iodine, which can easily dissolve in organic solvents, and the metal iodide, which can easily dissolve in water, makes these components act efficiently as catalysts in water and an organic solvent immiscible with water to give canthaxanthin with a high yield even within a short time.
In the process for producing canthaxanthin according to the present invention, oxidization of &bgr;-carotene is started by adding iodine halide or iodine, in step b), and the metal iodide, in step c), to a mixture of &bgr;-carotene, water, the organic solvent immiscible with water, and an alkali metal chlorate or an alkali metal bromate.
Iodine halide or iodine, and the metal iodide can be added to the reaction mixture separately or in a form of a mixture thereof. The iodine halide or iodine, and the metal iodide can be added to the reaction mixture continuously or in portion by portion, preferably all at once.
The iodine halide or iodine, and the metal iodide, can be each added to the reaction mixture in a solid form or in the form of solution in a solvent.
The solvent used for dissolving iodine halide or iodine, and the metal iodide, is preferably the same as the mixed solvent comprising water and the organic solvent immiscible with water, used for the oxidization of &bgr;-carotene. In this case, the organic solvent is preferably used in an amount of 1:50 to 1:3 of the amount used in the reaction, including 1:48, 1:45, 1:42, 1:39, 1:35, 1:32, 1:28, 1:25, 1:21, 1:17, 1:12, 1:9, 1:7, 1:5 and all values and subranges there between, and the water is preferably used in an amount of 1:50 to 1:30 of the amount used in the reaction, including 1:48, 1:45, 1:42, 1:39, 1:35, 1:32, 1:28, 1:25, 1:21, 1:17, 1:12, 1:9, 1:7, 1:5 and all values and subranges there between.
&bgr;-carotene can be commercially available, or prepared by any method described in the literature, e.g., U.S. Pat. No. 4,105,855 and German Patent No. 1068709 incorporated herein by reference.
Examples of the alkali metal chlorate or the alkali metal bromate include lithium chlorate, sodium chlorate, potassium chlorate, lithium bromate, sodium bromate and potassium bromate. The alkali metal chlorate or the alkali metal bromate can be used in one or more species.
The amount of the alkali metal chlorate or the alkali metal bromate is preferably from 1 to 100 times the weight of the &bgr;-carotene, including 3, 7, 11, 15, 20, 27, 36, 43, 50, 59, 63, 71, 85, 90, 95 and all values and subranges there between.
In the present invention, water and an organic solvent immiscible with water are used. Examples of the organic solvent immiscible with water include halogenated hydrocarbons such as methylene chloride, chloroform, carbon tetrachloride and dichloroethane; aromatic hydrocarbons such as benzene, toluene and xylene; aliphatic hydrocarbons such as pentane, hexane, cyclohexane and heptane; ethers such as diethyl ether, diisopropyl ether and methyl t-butyl ether; and esters such as butyl acetate, ethyl acetate and methyl acetate. The organic solvent can be used in one or more species.
The amount of the organic solvent, including that of an organic solvent used when the iodine halide or iodine in step b) and/or the metal halide in step c) are added in the form of a solution, is usually from 2 to 200 times the weight of &bgr;-carotene, including 5, 10, 20, 30, 40, 50, 60, 70, 80, 100, 120, 140, 150, 160, 170, 180, 190 and all values and subranges there between. Depending on the amount of the organic solvent, a part of &bgr;-carotene may remain in the solid form suspended in the reaction mixture. However, such a suspension does not inhibit the progress of the reaction.
The amount of water, including that of water used, when the iodine halide or iodine in step b) and/or the metal halide in step c) are added in the form of a solution, is usually from 1 to 50 times the total weight of the alkali metal chlorate and the alkali metal bromate, including 5, 10, 15, 20, 25, 30, 35, 40, 45 and all values and subranges there between.
Upon the oxidiz
Kajiyashiki Tsuyoshi
Katayama Naoyuki
Kitayama Masahiko
Mori Toshiki
Kuraray Co. Ltd.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Parsa J.
Richter Johann
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