Novel chromium propionate crystal as well as preparation method and application thereof

Abstract

The invention discloses a novel chromium propionate crystal and a preparation method and application thereof, the chemical formula of the chromium propionate crystal is C21H41O18Cr3, the crystal system of the chromium propionate crystal belongs to a tetragonal crystal system, the space group is P43, and the chromium propionate crystal comprises the following cell parameters: a = 16.5763 (4), b = 16.5763 (4), and c = 12.6394 (4); a is equal to 90 degrees, beta is equal to 90 degrees, gamma is equal to 90 degrees, and the cell volume is 3473.0 (2) 3. According to the invention, a novel chromium propionate single crystal structure is prepared, a stable trivalent chromium compound is synthesized, the utilization value of chromium is provided, and a trace element nutritional supplement is provided for dietary supplement and animal feed.

Description

Technical Field

[0001] The invention belongs to the technical field of additives, and in particular relates to a novel chromium propionate crystal and a preparation method and application thereof. Background Art

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

[0003] Propionic acid and propionate salts are important feed preservatives. They have a good inhibitory effect on Gram-negative bacteria and are harmless to yeast. The amount added to feed is less than 0.3% in terms of propionic acid. They prevent the loss of nutrients in feed during storage and reduce the number of microorganisms in feed. Propionic acid is a colorless liquid with volatility.

[0004] The research and development and application of chromium propionate have a history of more than 20 years. Chromium propionate products have been used in beef cattle, dairy cows, poultry and pigs in more than 30 countries around the world. There are currently two main methods for synthesizing chromium propionate: one is to obtain it by redox reaction: for example, in Chinese patent document CN86100694B and US patent document US 4644073, propionic acid can react with potassium dichromate and propylene glycol to generate a green oily substance, but by-products such as malonic acid and potassium salt are produced, which are not easy to separate; the other is to react propionic acid with a soluble trivalent chromium salt, and then recrystallize the crude chromium propionate with an organic solvent, such as Chinese patent documents CN102351680A, CN108147961A, CN11225659B and document "Fast Atom Bombardment Mass Spectrometry Study of Triple-bridged Oxygen Trinuclear Chromium Fatty Acid Complexes", although the synthesis method and the synthetic product have been studied, no single crystal has been obtained, and there is no detailed structural evidence. Summary of the invention

[0005] In order to overcome the problems in the prior art, the present invention provides a new type of chromium propionate crystal and a preparation method and application thereof, and a chromium propionate single crystal structure is prepared, laying a good foundation for the subsequent large-scale production of high-purity samples of chromium propionate powder.

[0006] In order to solve the above technical problems, the technical solution proposed by the present invention is: The present invention provides a novel chromium propionate crystal, wherein the chemical formula of the chromium propionate crystal is C 21 H 41 O 18Cr3, the crystal system of the chromium propionate crystal belongs to the tetragonal system, the space group is P43, and the chromium propionate crystal includes 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 embodiment, in the novel chromium propionate crystal provided by the present invention, the structural formula of the chromium propionate crystal is as shown below: .

[0008] Based on the same technical concept, the present invention also provides a method for preparing the novel chromium propionate crystal, comprising the following steps: S1. Dissolve the soluble chromium salt powder and perform ultrasonic treatment for later use. Then add alkali and stir evenly until the pH value of the solution is 5-6. After the reaction, filter by suction. Wash the filter cake with water to obtain a blue colloidal wet material.

[0009] S2. Dissolve the blue colloidal wet material obtained in step S1 with propionic acid, stir it into a slurry, start the reflux device, heat it to react until the solution turns green, and then concentrate it into a paste.

[0010] S3, adjusting the pH of the paste material obtained in step S2 to 6-7, and performing diffusion crystallization with ethyl acetate to obtain novel chromium propionate crystals.

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

[0012] As an optional embodiment, 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 embodiment, in the preparation method provided by the present invention, in step S1, the base is selected from one or more of sodium hydroxide, potassium hydroxide, calcium hydroxide, and ammonia water.

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

[0015] As an optional embodiment, 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 embodiment, in the preparation method provided by the present invention, in step S3, the pH is adjusted to 6-7 with ammonia water.

[0017] As an optional embodiment, 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 use of the novel chromium propionate crystals prepared by the above-mentioned preparation method as animal feed additives.

[0019] Compared with the prior art, the present invention has the following beneficial effects: Chromium has multiple valence states, and its high valence state cannot be absorbed and utilized by organisms. The present invention prepares a new type of chromium propionate single crystal structure and synthesizes a stable trivalent chromium compound, which provides the utilization value of chromium and lays a good foundation for the subsequent large-scale production of high-purity samples of chromium propionate powder. It provides a trace element nutritional supplement for food and animal feed. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 This is a microscopic picture of the chromium propionate crystals prepared in Example 1; Figure 2 The spatial structure diagram of the chromium propionate crystal prepared in Example 1; Figure 3 The graphs of the chromate single crystal and the sample in Example 1 are compared. DETAILED DESCRIPTION

[0022] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively and meticulously below in conjunction with the accompanying drawings and preferred embodiments of the present invention, but the protection scope of the present invention is not limited to the following specific embodiments.

[0023] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

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

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

[0026] After slightly dissolving the wet chromium hydroxide material with 50 ml of propionic acid, stir it into a slurry, add it into a three-necked flask, stir, turn on the reflux device, heat it to 135 degrees and react for 4 hours. The solution turns green and is concentrated to a certain volume. The solution is paste-like. Ammonia water is used to adjust the pH to 6-7. Ethyl acetate is used 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, ultrasonicate it, and set it aside. Then add 4.26 g of potassium hydroxide and stir evenly. At this time, the pH is 5-6. React for 1 hour, filter it, and wash the filter cake twice with water to obtain chromium hydroxide wet material, which is a blue gel.

[0028] After slightly dissolving the wet chromium hydroxide material with 50 ml of propionic acid, stir it into a slurry, add it into a three-necked flask, stir, turn on the reflux device, heat it to 135 degrees and react for 4 hours. The solution turns green and is concentrated to a certain volume. The solution is paste-like. Ammonia water is used to adjust the pH to 6-7. Ethyl acetate is used as a poor solvent for diffusion crystallization to obtain chromium propionate crystals with a yield of 82%.

[0029] Example 3 Dissolve 15.2 g (0.038 mol) of chromium nitrate nonahydrate powder in 150 ml of water, sonicate it ultrasonically, and set it aside. Then add 4.8 g of sodium hydroxide and stir evenly. At this time, the pH is 5-6. React for 1 hour, filter it with suction, and wash the filter cake twice with water to obtain wet chromium hydroxide, which is a blue colloid.

[0030] After slightly dissolving the wet chromium hydroxide material with 50 ml of propionic acid, stir it into a slurry, add it into a three-necked flask, stir, turn on the reflux device, heat it to 135 degrees and react for 4 hours. The solution turns green and is concentrated to a certain volume. The solution is paste-like. Ammonia water is used to adjust the pH to 6-7. Ethyl acetate is used as a poor solvent for diffusion crystallization to obtain chromium propionate crystals with a yield of 83%.

[0031] Example 4 Dissolve 10g (0.038mol) of chromium chloride hexahydrate powder in 150ml of water, sonicate it ultrasonically, and set it aside. Then add 7.04g of calcium hydroxide and stir evenly. At this time, the pH is 5-6. React for 1 hour, filter it with suction, and wash the filter cake twice with water to obtain chromium hydroxide wet material, which is a blue colloid.

[0032] After slightly dissolving the wet chromium hydroxide material with 50 ml of propionic acid, stir it into a slurry, add it into a three-necked flask, stir, turn on the reflux device, heat it to 115 degrees and react for 4 hours. The solution will turn green. After concentrating to a certain volume, the solution will be in a paste state. Use ammonia water to adjust the pH to 6-7. Use ethyl acetate 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 chloride hexahydrate powder in 150ml of water, sonicate it, set aside, add ammonia water to a pH of 5-6, react for 1 hour, filter it, wash the filter cake twice with water, and obtain wet chromium hydroxide, which is a blue colloid.

[0034] After slightly dissolving the wet chromium hydroxide material with 50 ml of propionic acid, stir it into a slurry, add it into a three-necked flask, stir, turn on the reflux device, heat it to 135 degrees and react for 2 hours. The solution will turn green. After concentrating to a certain volume, the solution will be in a paste state. Use ammonia water to adjust the pH to 6-7. Use ethyl acetate 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 for reaction for 4 hours, and 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 for reaction for 4 hours, and 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 is used as a poor solvent for diffusion crystallization, and the remaining steps are the same as those in Example 1, and no chromium propionate crystals are obtained.

[0038] Comparative Example 2 The difference from Example 1 is that the pH is adjusted to 7.5-8 with aqueous ammonia before crystallization, and the remaining steps are the same as in Example 1, and no chromium propionate crystals are obtained.

[0039] Comparative Example 3 The difference from Example 1 is that propionic acid is used to adjust the pH to 5-5.5 before crystallization, and the remaining steps are the same as in Example 1, and no chromium propionate crystals are obtained.

[0040] Comparative Example 4 Add 5.8 g (0.038 mol) of chromium trioxide powder and 50 ml of propionic acid into a three-necked flask, stir, turn on the reflux device, raise the temperature to 135 degrees and react for 4 hours. The chromium trioxide powder does not react.

[0041] The green needle-shaped crystals obtained in Example 1 ( Figure 1 ) The product was observed under a microscope and magnified (10*10). The results are as follows Figure 1 As shown. A single crystal of 0.5 mm × 0.15 mm × 0.13 mm was placed on a Bruker Smart 1000 CCD single crystal diffractometer. Using a graphite monochromatized 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, and all non-hydrogen atomic coordinates and anisotropy parameters were corrected by the full matrix least squares method. As shown in Table 1, the crystal is a tetragonal system with a space group of 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=1.411g / cm 3 , F(000)=1532.0, F(000)=1536.72, R1=0.0547 (4187), wR2=0.1301 (5520).

[0042] Table 1: Chromium propionate crystal parameters

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

[0044] The spatial structure of chromium propionate crystal is shown in the figure Figure 2 As shown, black represents oxygen, white represents hydrogen, gray represents carbon, and dark gray represents chromium. Figure 2It can be seen that the three chromium atoms are connected to each other through the μ3-O atom coplanar with them. There are two propionate groups as bidentate ligands between each two chromium atoms. There is an oxygen atom from a water molecule on each Cr(2) and Cr(3) atom to form a terminal coordination, while another oxygen atom from a propionate group on Cr(1) atom is coordinated from this terminal. O(4), O(10) and O(13) are also on the basal plane composed of three chromium and μ3-O atoms. Each chromium atom is surrounded by six oxygen atoms in a distorted octahedral configuration. The three octahedra have μ3-O atoms as common vertices. The bond length between chromium and the bridge propionate oxygen atom Cr-μ-O is in the range of 1.95-1.99 Å, which is slightly longer than the Cr-μ3-O bond, while the bond length between chromium and the terminal oxygen atom Cr-O is 2.02-2.04 Å. This may be due to the existence of a certain degree of delocalized π bonds between the trinuclear metal complexes in addition to the σ bonds.

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

[0046] Table 2: Coordinates of atoms in chromium propionate chelate

[0047] Using single crystal of chromic acid as standard spectrum, the standard spectrum and the obtained sample were subjected to X-ray powder diffraction analysis, such as Figure 3 As shown, the light color is the standard spectrum of chromic acid propionate, and the dark color is the sample of Example 1. It is found that the peaks of the two are basically the same, indicating that the crystal forms are consistent. The powder diffraction comparison shows that the single crystal spectrum can be used as a standard spectrum, and the synthesized powder sample is used as a reference, which lays a good foundation for the subsequent large-scale production of high-purity samples of chromium propionate powder.

[0048] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the scope of protection of the present invention.

Claims

1. A novel chromium propionate crystal, characterized in that: The chemical formula of the chromium propionate crystal is C 21 H 41 O 18 Cr3, the crystal system of the chromium propionate crystal belongs to the tetragonal system, the space group is P43, and the chromium propionate crystal includes 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 according to claim 1, characterized in that: The structural formula of the chromium propionate crystal is shown below: 。 3. A method for preparing a novel chromium propionate crystal according to claim 1 or 2, characterized in that: The following steps are involved: S1. Dissolve the soluble chromium salt powder and perform ultrasonic treatment for later use. Then add alkali and stir evenly until the pH value of the solution is 5-6. After the reaction, filter with suction. Wash the filter cake with water to obtain a blue colloidal wet material. S2, dissolving the blue colloidal wet material obtained in step S1 with propionic acid, stirring into a slurry, opening a reflux device, heating to react until the solution turns green, and then concentrating to a paste; S3, adjusting the pH of the paste material obtained in step S2 to 6-7, and performing diffusion crystallization with ethyl acetate to obtain novel chromium propionate crystals.

4. The method for preparing the novel chromium propionate crystal according to claim 3, characterized in that: In step S1, the molar ratio of the chromium salt to the base is 0.1-0.5:1; the base is selected from one or more of sodium hydroxide, potassium hydroxide, calcium hydroxide, and ammonia water.

5. The method for preparing the novel chromium propionate crystal according to claim 3, characterized in that: In step S1, the reaction time after adjusting the pH is 0.1-4 h.

6. The method for preparing the novel chromium propionate crystal according to claim 3, characterized in that: In step S2, the molar ratio of propionic acid to chromium is 1-10:

1.

7. The method for preparing the novel chromium propionate crystal according to claim 3, characterized in that: In step S2, the temperature of the temperature-raising reaction is 115-135° C., and the reaction time is 2-4 h.

8. The method for preparing the novel chromium propionate crystal according to claim 3, characterized in that: In step S3, the pH is adjusted to 6-7 with aqueous ammonia.

9. The method for preparing the novel chromium propionate crystal according to claim 3, characterized in that: The soluble chromium salt is selected from one or more of chromium trichloride, chromium sulfate or chromium nitrate.

10. Use of the novel chromium propionate crystals according to claim 1 or the novel chromium propionate crystals prepared by the preparation method according to any one of claims 3 to 8 as a dietary supplement or an animal feed additive.

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