A novel chromium propionate crystal and a preparation method and application thereof

Abstract

The application discloses a novel chromium propionate crystal and a preparation method and application thereof. 21 H 41 O 18 Cr3, the crystal system of the chromium propionate crystal belongs to a tetragonal system, a space group is P43, the crystal cell parameters of the chromium propionate crystal include the following: a=16.5763(4)Å, b=16.5763(4)Å, c=12.6394(4)Å; alpha=90°, beta=90°, gamma=90°, and a crystal cell volume is 3473.0(2)Å 3 The application prepares a novel single crystal structure of chromium propionate, synthesizes a stable trivalent chromium compound, provides utilization value of chromium, and provides a trace element nutrient supplement for food and animal feed.

Description

Technical Field

[0001] This invention belongs to the field of additive technology, and in particular relates to a novel chromium propionate crystal, its preparation method, and its application. Background Technology

[0002] Chromium is an essential trace element for animals. It participates in the synthesis of proteins and the metabolism of nucleic acids and fats, reduces body fat content, and enhances the body's resistance to adverse conditions, thereby improving the body's growth performance under stress.

[0003] Propionic acid and its propionate salts are important feed preservatives. They have a good inhibitory effect on Gram-negative bacteria and are harmless to yeasts. The amount added to feed, calculated as propionic acid, should be below 0.3%. This prevents nutrient loss during feed storage and reduces the number of microorganisms in the feed. Propionic acid is a colorless liquid and is volatile.

[0004] Chromium propionate has been researched and applied for over 20 years, and its products are used in beef cattle, dairy cattle, poultry, and pigs in more than 30 countries worldwide. Currently, there are two main methods for synthesizing chromium propionate: one is through redox reactions, such as Chinese patent document CN86100694B and US patent document US 4644073, which utilize propionic acid to react with potassium dichromate and propylene glycol to produce a green oily substance, but byproducts such as malonic acid and potassium salts are produced and are difficult to separate; the other is by reacting propionic acid with soluble trivalent chromium salts, and then recrystallizing the crude chromium propionate using organic solvents, such as Chinese patent documents CN102351680A, CN108147961A, CN11225659B and the document "Fast Atom Bombardment Mass Spectrometry Study of Triple-Bridged Oxygen Trinuclear Chromium Fatty Acid Complexes". Although the synthesis methods and products have been studied, no single crystals have been obtained, and there is no detailed structural evidence. Summary of the Invention

[0005] To overcome the problems in the prior art, this invention provides a novel chromium propionate crystal, its preparation method, and its application. A single crystal structure of chromium propionate was prepared, laying a good foundation for the subsequent large-scale production of high-purity chromium propionate powder samples.

[0006] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows: This invention provides a novel chromium propionate crystal, the chemical formula of which is C0. 21 H 41 O 18Cr3, the chromium propionate crystal belongs to the tetragonal crystal system, space group P43, and the chromium propionate crystal has the following unit cell parameters: a=16.5763(4) Å, b=16.5763(4) Å, c=12.6394(4) Å; α=90°, β=90°, γ=90°, and the unit cell volume is 3473.0(2) Å. 3 .

[0007] As an optional implementation, in the novel chromium propionate crystal provided by the present invention, the structural formula of the chromium propionate crystal is shown below. .

[0008] Based on the same technical concept, the present invention also provides a method for preparing the above-mentioned novel chromium propionate crystals, comprising the following steps: S1. Dissolve the soluble chromium salt powder and sonicate it for later use. Then add alkali and stir until the solution pH is 5-6. After the reaction, filter it and wash the filter cake with water to obtain a blue gelatinous wet material.

[0009] S2. Dissolve the blue gel-like wet material obtained in step S1 with propionic acid, stir it into a slurry, turn on the reflux device, heat the reaction until the solution turns green, and then concentrate it into a paste.

[0010] S3. Adjust the pH of the paste obtained in step S2 to 6-7, and crystallize it by diffusion with ethyl acetate to obtain novel chromium propionate crystals.

[0011] As an optional implementation, in the preparation method provided by the present invention, in step S1, the molar ratio of the chromium salt and the alkali is 0.1~0.5:1.

[0012] As an optional implementation, in the preparation method provided by the present invention, in step S1, the reaction time after adjusting the pH is 1 hour.

[0013] As an optional implementation, in the preparation method provided by the present invention, in step S1, the alkali is selected from one or more of sodium hydroxide, potassium hydroxide, calcium hydroxide, and ammonia water.

[0014] As an optional implementation method, in the preparation method provided by the present invention, in step S2, the temperature of the heating reaction is 115-135℃, and the reaction time is 2-4 h.

[0015] As an optional implementation method, in the preparation method provided by the present invention, in step S2, the molar ratio of propionic acid to chromium is 1~10:1.

[0016] As an optional implementation, in the preparation method provided by the present invention, in step S3, the pH is adjusted to 6-7 with ammonia.

[0017] As an optional implementation, in the preparation method provided by the present invention, the soluble chromium salt is selected from one or more of chromium trichloride, chromium sulfate, or chromium nitrate.

[0018] Based on the same technical concept, the present invention also provides the application of the novel chromium propionate crystals prepared by the above-described preparation method as animal feed additives.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: Chromium exists in multiple valence states, but its higher valence states cannot be absorbed and utilized by organic matter. This invention yields a novel single-crystal structure of chromium propionate and synthesizes stable trivalent chromium compounds, providing a valuable resource for the utilization of chromium and laying a solid foundation for the subsequent large-scale production of high-purity chromium propionate powder. It also provides a trace element nutritional supplement for animal feed and animal diets. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 Microscopic images of chromium propionate crystals prepared in Example 1; Figure 2 This is a spatial structure diagram of the chromium propionate crystals prepared in Example 1; Figure 3 The results show the spectrum comparison between the single crystal of propionic chromate and the sample in Example 1. Detailed Implementation

[0022] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0023] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0024] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0025] Example 1 Dissolve 10g (0.038mol) of chromium trichloride hexahydrate powder in 150ml of water, sonicate the solution, and set aside. Then add 4.5g of sodium hydroxide and stir until homogeneous. At this point, the pH is 5-6. React for 1 hour, filter, and wash the filter cake twice with water to obtain wet chromium hydroxide, which is a blue gel.

[0026] Dissolve the wet chromium hydroxide in 50 ml of propionic acid and stir to form a slurry. Add the slurry to a three-necked flask, stir, turn on the reflux device, and heat to 135 degrees Celsius for 4 hours. The solution turns green. Concentrate to a certain volume and the solution becomes a paste. Adjust the pH to 6-7 with ammonia water. Use ethyl acetate as a poor solvent for diffusion crystallization to obtain chromium propionate crystals with a yield of 85%.

[0027] Example 2 Dissolve 14.90 g (0.038 mol) of chromium sulfate powder in 150 ml of water, sonicate the solution, and set aside. Then add 4.26 g of potassium hydroxide and stir until homogeneous. At this point, the pH is 5-6. React for 1 hour, filter, and wash the filter cake twice with water to obtain wet chromium hydroxide, which is a blue gel.

[0028] The wet chromium hydroxide was dissolved in 50 ml of propionic acid and stirred into a slurry. The slurry was then added to a three-necked flask, stirred, and the reflux device was turned on. The temperature was raised to 135 degrees Celsius and reacted for 4 hours. The solution turned green. After being concentrated to a certain volume, the solution became a paste. The pH was adjusted to 6-7 with ammonia water. Chromium propionate crystals were obtained by diffusion crystallization using ethyl acetate as a poor solvent. The yield was 82%.

[0029] Example 3 15.2 g (0.038 mol) of chromium nitrate nonahydrate powder was dissolved in 150 ml of water and sonicated. The solution was then set aside. 4.8 g of sodium hydroxide was added and stirred until homogeneous. The pH was 5-6 at this point. The reaction was carried out for 1 hour. The solution was then filtered, and the filter cake was washed twice with water to obtain wet chromium hydroxide, which was a blue gel.

[0030] The wet chromium hydroxide was dissolved in 50 ml of propionic acid and stirred into a slurry. The slurry was then added to a three-necked flask, stirred, and the reflux device was turned on. The temperature was raised to 135 degrees Celsius and reacted for 4 hours. The solution turned green. After being concentrated to a certain volume, the solution became a paste. The pH was adjusted to 6-7 with ammonia water. Chromium propionate crystals were obtained by diffusion crystallization using ethyl acetate as a poor solvent. The yield was 83%.

[0031] Example 4 Dissolve 10g (0.038mol) of chromium trichloride hexahydrate powder in 150ml of water, sonicate the solution, and set aside. Then add 7.04g of calcium hydroxide and stir until homogeneous. At this point, the pH is 5-6. React for 1 hour, filter, and wash the filter cake twice with water to obtain wet chromium hydroxide, which is a blue gel.

[0032] The wet chromium hydroxide was dissolved in 50 ml of propionic acid and stirred into a slurry. The slurry was then added to a three-necked flask, stirred, and the reflux device was turned on. The temperature was raised to 115 degrees Celsius and reacted for 4 hours. The solution turned green. After being concentrated to a certain volume, the solution became a paste. The pH was adjusted to 6-7 with ammonia water. Ethyl acetate was used as a poor solvent for diffusion crystallization to obtain a small amount of chromium propionate crystals with a yield of about 56%.

[0033] Example 5 Dissolve 10g (0.038mol) of chromium trichloride hexahydrate powder in 150ml of water, sonicate the solution, and set aside. Add ammonia water to adjust the pH to 5-6, react for 1 hour, filter, and wash the filter cake twice with water to obtain wet chromium hydroxide, which is a blue gel.

[0034] The wet chromium hydroxide was dissolved in 50 ml of propionic acid and stirred into a slurry. The slurry was then added to a three-necked flask, stirred, and the reflux device was turned on. The temperature was raised to 135 degrees Celsius and reacted for 2 hours. The solution turned green. After being concentrated to a certain volume, the solution became a paste. The pH was adjusted to 6-7 with ammonia water. Ethyl acetate was used as a poor solvent for diffusion crystallization to obtain a small amount of chromium propionate crystals with a yield of about 49%.

[0035] Example 6 The difference from Example 1 is that the temperature is raised to 110 degrees and the reaction is carried out for 4 hours. The remaining steps are the same as in Example 1, and a small amount of chromium propionate crystals can be obtained with a yield of about 18%.

[0036] Example 7 The difference from Example 1 is that the temperature is raised to 140 degrees and the reaction is carried out for 4 hours. The remaining steps are the same as in Example 1, and a small amount of chromium propionate crystals can be obtained with a yield of about 21%.

[0037] Comparative Example 1 The difference from Example 1 is that petroleum ether was used as a poor solvent for diffusion crystallization, while the remaining steps were the same as in Example 1, and chromium propionate crystals were not obtained.

[0038] Comparative Example 2 The difference from Example 1 is that the pH was adjusted to 7.5-8 with ammonia before crystallization. The remaining steps were the same as in Example 1, and chromium propionate crystals were not obtained.

[0039] Comparative Example 3 The difference from Example 1 is that the pH was adjusted to 5-5.5 with propionic acid before crystallization. The remaining steps were the same as in Example 1, and chromium propionate crystals were not obtained.

[0040] Comparative Example 4 5.8 g (0.038 mol) of chromium trioxide powder and 50 ml of propionic acid were added to a three-necked flask, stirred, and the reflux device was turned on. The temperature was raised to 135 degrees and the reaction was carried out for 4 hours. The chromium trioxide powder did not react.

[0041] The green needle-like crystals obtained in Example 1 ( Figure 1 The product was observed under a microscope at a magnification of 10*10, and the results are as follows. Figure 1 As shown. A single crystal of size 0.5 mm × 0.15 mm × 0.13 mm was placed on a Bruker Smart 1000 CCD single crystal diffractometer. Using a graphite monochromatic Mo Kα (λ = 0.071073 nm) radiation source, at 298 K, within the range of 1.98° ≤ θ ≤ 24.98°, a total of 6098 independent diffraction points were collected, of which 3201 were observable. The crystal structure was given by the direct method. The coordinates of all non-hydrogen atoms and anisotropy parameters were corrected by the full matrix least squares method, as shown in Table 1. The crystal is tetragonal, space group P43, a = 16.5763(4) Å, b = 16.5763(4) Å, c = 12.6394(4) Å; α = 90°, β = 90°, γ = 90°; Z = 4, V = 3473.0(2) Å 3 Dc = 1.411 g / cm³ 3 , F(000)=1532.0, F(000)=1536.72, R1=0.0547 (4187), wR2=0.1301 (5520).

[0042] Table 1: Parameters of Chromium Propionate Crystals

[0043] The structural formula of chromium propionate crystals is shown below:

[0044] The spatial structure diagram of chromium propionate crystals is shown below. Figure 2 As shown, black represents oxygen, white represents hydrogen, gray represents carbon, and dark gray represents chromium. This is based on the structural formula and... Figure 2It is known that the three chromium atoms are interconnected through the coplanar μ3-O atoms. There are two propionic acid groups acting as bidentate ligands between each pair of chromium atoms. Each of the Cr(2) and Cr(3) atoms has an oxygen atom from a water molecule forming a terminal coordination, while the Cr(1) atom has another oxygen atom from a propionic acid group coordinating from this terminal coordination. O(4), O(10), and O(13) are also on the base plane composed of the three chromium atoms and μ3-O. Each chromium atom is surrounded by a distorted octahedral configuration composed of six oxygen atoms. The three octahedra share a common vertex with the μ3-O atom. The bond length Cr-μ-O between chromium and the bridging propionic acid oxygen atom is in the range of 1.95-1.99 Å, which is slightly longer than the Cr-μ3-O bond. The bond length Cr-O between chromium and the terminal oxygen atom is 2.02-2.04 Å. This may be because, in addition to σ bonds, there are also a certain degree of delocalized π bonds between the trinuclear metal complexes.

[0045] The atomic coordinates of the chromium propionate chelate are shown in Table 2.

[0046] Table 2: Atomic coordinates of chromium propionate chelate

[0047] Using single crystals of propionic chromate as the standard spectrum, X-ray powder diffraction analysis was performed on the obtained samples along with the standard spectrum. Figure 3 As shown, the light-colored spectrum represents the standard spectrum of chromium propionate, while the dark-colored spectrum represents the sample from Example 1. The peak shapes of the two are found to be essentially identical, indicating consistent crystal form. Powder diffraction comparison demonstrates that the single-crystal spectrum can serve as a standard spectrum, and the synthesized powder sample can be used as a reference. This lays a solid foundation for the subsequent large-scale production of high-purity chromium propionate powder samples.

[0048] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. However, it should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a novel chromium propionate crystal, characterized in that, Includes the following steps: S1. Dissolve the soluble chromium salt powder and sonicate it for later use. Then add alkali and stir until the solution pH is 5-6. After the reaction, filter it and wash the filter cake with water to obtain a blue gelatinous wet material. S2. Dissolve the blue gel-like wet material obtained in step S1 with propionic acid, stir into a slurry, turn on the reflux device, heat the reaction until the solution turns green, and then concentrate it into a paste; the temperature of the reaction is 115-135℃, and the reaction time is 2-4 h. S3. Adjust the pH of the paste material obtained in step S2 to 6-7, and crystallize it by diffusion with ethyl acetate to obtain novel chromium propionate crystals. The chemical formula of the chromium propionate crystals prepared above is C1 21 H 41 O 18 Cr3, the chromium propionate crystal belongs to the tetragonal crystal system with space group P43, and the chromium propionate crystal has the following unit cell parameters: a=16.5763(4) Å, b=16.5763(4) Å, c=12.6394(4) Å; α=90°, β=90°, γ=90°, and the unit cell volume is 3473.0(2) Å. 3 .

2. The method for preparing the novel chromium propionate crystals according to claim 1, characterized in that, In step S1, the molar ratio of the chromium salt to the alkali is 0.1~0.5:1; the alkali is selected from one or more of sodium hydroxide, potassium hydroxide, calcium hydroxide, and ammonia water.

3. The method for preparing the novel chromium propionate crystals according to claim 1, characterized in that, In step S1, the reaction time after pH adjustment is 0.1~4h.

4. The method for preparing the novel chromium propionate crystals according to claim 1, characterized in that, In step S2, the molar ratio of propionic acid to chromium is 1~10:

1.

5. The method for preparing the novel chromium propionate crystals according to claim 1, characterized in that, In step S3, the pH is adjusted to 6-7 using ammonia.

6. The method for preparing the novel chromium propionate crystals according to claim 1, characterized in that, The soluble chromium salt is selected from one or more of chromium trichloride, chromium sulfate, or chromium nitrate.

7. The application of the novel chromium propionate crystals prepared by any of the preparation methods described in claims 1-5 as a dietary supplement or animal feed additive.

Images