A pre-nursery feed additive and its preparation method

Abstract

The present invention belongs to the field of organic synthesis, and particularly relates to a pre-preservation feed additive and a preparation method thereof. The additive is DL-methionine complex zinc. The reaction steps include: using DL-methionine and a zinc source as raw materials, and carrying out a chelation reaction in the presence of an ionic liquid catalyst to generate DL-methionine complex zinc. The metal ionic liquid catalyst adopted by the present invention can improve the reaction activity of the zinc source, enabling the reaction to proceed efficiently and rapidly. Moreover, there is no need to additionally add an alkali catalyst, the reaction temperature is low, the reaction time is short, and the post-treatment operation is simple, greatly reducing the production cost, conforming to the trend of green chemical industry, and being suitable for industrial production.

Description

Technical Field

[0001] The invention belongs to the field of organic synthesis, and in particular relates to a pre-nursery feed additive and a preparation method thereof. Background Art

[0002] Since the discovery and preparation of chelates by the chemical community in the early 17th century, the research and application of chelates have been greatly developed in many industries. In the 1970s, metal amino acid chelates began to be used in animal nutrition, and their application fields are becoming more and more extensive. The American Official Feed Management Association defines the concept of amino acid chelates as follows: Amino acid metal element chelates refer to products formed by the reaction of 1 mol of metal ions in soluble metal salts with 1 to 3 mol of amino acids, and the molecular weight of the generated chelates generally does not exceed 800, which is conducive to the complete transportation and absorption of trace elements in the form of chelates, and can effectively release metal ions when needed. Amino acid metal chelates have the characteristics of stable chemical structure, high biological efficacy, can enhance immunity, improve disease resistance, and are green and environmentally friendly.

[0003] As one of the important trace element additives, DL-methionine complex zinc chelate reacts inorganic zinc with DL-methionine to produce a chelate with a ring structure. Because the molecular structure of amino acid zinc is closer to the action form of Zn in the body, it is a trace element supplement close to the natural form of the animal body. As a new feed additive, it can improve animal growth, reproduction and health, and has the functions of promoting the rapid proliferation of tongue mucosal taste bud cells, regulating appetite, inhibiting certain harmful bacteria in the intestine, prolonging the residence time of food in the digestive tract, and improving the secretion function of the digestive system and the activity of enzymes in tissue cells. The absorption rate of DL-methionine complex zinc chelate in animals is 2-4 times that of ordinary inorganic zinc, and methionine itself is also a high-level nutrient. Animals can absorb zinc while absorbing methionine, which is of great biological value.

[0004] Pre-nursery feed is specially designed for newly weaned piglets to meet their nutritional needs for growth and development. The feed during this period should not only be easy to digest and absorb, but also provide enough energy, protein and essential amino acids to help piglets pass the weaning stress period smoothly, reduce the occurrence of diseases and improve the survival rate. Therefore, DL-methionine complex zinc chelate is widely used in pre-nursery feed.

[0005] CN 111978222 A relates to a preparation method of DL-methionine complex zinc as a feed additive. In this method, an aqueous solution of methionine is heated to 60 - 80 °C and kept at a constant temperature. Then zinc salt is added. After stirring, an aqueous solution of methionine metal salt and corresponding carbonate is added to adjust the pH. Then it is heated to 60 - 110 °C and reacted for 0.5 - 1.0 hour. Then it is filtered and washed with normal temperature water to obtain the methionine zinc product. This method produces a large amount of by-products, resulting in a large amount of wastewater discharge, difficult treatment, and high treatment cost. Considering the current national environmental protection policies, it is urgent to find a new synthesis method to reduce the wastewater discharged during the production of methionine zinc chelate and solve the pollution problem from the source.

[0006] CN101914049 A discloses a method for preparing methionine zinc using methionine and zinc oxide as raw materials and formic acid or acetic acid as an initiator. The granular methionine zinc product is obtained through separation, drying, and sieving. The product obtained by this method is easy to dry after separation, does not need to be pulverized, and avoids dust. However, this reaction can only occur under the action of an initiator, has a long reaction time, and the zinc content in the prepared methionine zinc is relatively low.

[0007] CN111094301 A discloses a method for preparing methionine-metal chelate. Methionine and Ca(OH)2 are mixed, and metal nitrate or metal chloride is added to the mixture to generate methionine-metal chelate. Although this method can improve the recovery rate of methionine-metal chelate and prevent the formation of insoluble by-product salts, this method will generate by-products Ca(NO3)2 or CaCl2, producing metal waste, and the process steps are complex, the production cost is high, which is not conducive to industrial production.

[0008] Based on this, it is urgent to develop a method for preparing DL-methionine complex zinc as a pre-nursery feed additive with mild reaction conditions, environmental friendliness, and suitability for industrial production. Summary of the Invention

[0009] In view of the problems existing in the prior art, the purpose of the present invention is to provide a preparation method of DL-methionine complex zinc as a pre-nursery feed additive to solve the problems of non-environmental protection, non-mild reaction conditions, low chelation rate, and non-suitability for industrial production existing in the prior art. The present invention is realized through the following technical solutions:

[0010] A preparation method of a pre-nursery feed additive, wherein the additive is DL-methionine complex zinc, and the preparation method comprises the following steps:

[0011] Using DL-methionine and a zinc source as raw materials, a chelation reaction occurs in the presence of an ionic liquid catalyst to generate a DL-methionine complex zinc pre-nursery feed additive;

[0012] Among them, the zinc source is selected from one or more of zinc hydroxide, zinc oxide, zinc nitrate, zinc sulfate and zinc carbonate;

[0013] The structural formula of the ionic liquid catalyst is:

[0014] In some embodiments, the reaction solvent is selected from one or more of water, methanol, ethanol and isopropanol.

[0015] In some embodiments, the reaction solvent is preferably water.

[0016] In some embodiments, the zinc source is preferably zinc hydroxide or zinc oxide.

[0017] In some embodiments, the molar ratio of DL-methionine to the zinc source is (2.0 - 2.5):1; the molar ratio of DL-methionine to the ionic liquid catalyst is 1:(0.005 - 0.015).

[0018] In some embodiments, after the reaction is completed, the reaction solution is cooled to 10 - 15 °C and then filtered by suction, and the filter cake is washed with hot water, and then the obtained solid is dried in vacuum to obtain DL-methionine complex zinc.

[0019] In some embodiments, the residual solvent in the filtrate after filtration is removed by distillation under reduced pressure, and the residue is dried in vacuum to obtain the ionic liquid catalyst, which can be recycled.

[0020] In some embodiments, the reaction temperature is 20 - 50 °C and the reaction time is 20 - 40 min.

[0021] In some embodiments, its preparation method includes the following steps:

[0022] Add DL-methionine, zinc hydroxide and water into the reactor, then slowly add the ionic liquid catalyst, heat up to 35 °C and stir for reaction for 30 min; after the reaction is completed, cool the reaction solution to 15 °C and then filter by suction, and wash the filter cake with hot water, and then dry the obtained solid in vacuum at 110 °C to obtain DL-methionine complex zinc chelate.

[0023] On the other hand, the present invention also protects the pre-nursery feed additive prepared by the above preparation method.

[0024] The present invention has achieved the following beneficial effects:

[0025] 1) The metal ionic liquid catalyst adopted by the present invention can improve the reaction activity of the zinc source, and then can react with methionine efficiently to generate methionine zinc chelate, with a high yield and chelation rate. In addition, compared with the prior art, the present invention does not produce inorganic salt wastewater, is green and environmentally friendly, and is suitable for industrial production.

[0026] 2) The reaction conditions of the present invention are mild, with a low reaction temperature and a short reaction time.

[0027] 3) For the filtrate after filtration in the present invention, the residual solvent is removed by vacuum distillation, and the residue is vacuum dried to obtain an ionic liquid catalyst, which can be recycled. Specific Embodiments

[0028] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0029] The endpoints and any values within the scope described in the present invention are not limited to the exact scope or value. These scopes or values should be understood to include values close to these scopes or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0030] Preparation Example 1: Preparation of a metal ionic liquid catalyst

[0031] Step 1: Preparation of an ionic liquid intermediate

[0032]

[0033] Under nitrogen protection, N,N'-carbonyldiimidazole (0.1 mol) and 1-chlorobutane (0.2 mol) are added to a reactor, and then acetonitrile (200 mL) and ethanol (30 mL) are added in sequence. The temperature is raised to 70 °C and the mixture is refluxed and stirred for 12 h. After the reaction is completed, it is cooled to room temperature. Petroleum ether (200 mL) and ethyl acetate (100 mL) are added to the solution, and a brown viscous liquid precipitates. The mixture is extracted through a separatory funnel, and the residual solvent is removed by rotary evaporation. Finally, the collected viscous liquid is vacuum dried to obtain an ionic liquid intermediate.

[0034] Step 2: Preparation of a metal ionic liquid catalyst

[0035]

[0036] Under nitrogen protection, the ionic liquid intermediate (0.1 mol) prepared in Step 1 is added to a reactor, and then ZnCl2·2H2O (0.2 mol) is added. The temperature is raised to 85 °C and the mixture is stirred for 8 h. After the reaction is completed, the solvent is removed by rotary evaporation, and it is vacuum dried at 110 °C for 10 h to obtain a metal ionic liquid catalyst with a yield of 92.0%.

[0037] 1 1H NMR (400 MHz, DMSO-d6) δ 7.61 (s, 2H), 7.17 (s, 2H), 6.86 (s, 2H), 3.97 - 3.92 (m, 4H), 1.66 - 1.59 (m, 4H), 1.24 - 1.19 (m, 4H), 0.91 - 0.85 (m, 6H).

[0038] Example 1

[0039] DL-Methionine (30.0 g, 0.2 mol), zinc hydroxide (10.0 g, 0.1 mol) and water (200 mL) were added to a reactor, and then the ionic liquid catalyst (0.01 mol) obtained in Preparation Example 1 was slowly added, and the temperature was raised to 35 °C and stirred for reaction for 30 min. After the reaction was completed, the reaction solution was cooled to 15 °C and then filtered by suction, and the filter cake was washed with hot water. Then the obtained solid was vacuum dried at 110 °C to obtain DL-methionine complex zinc chelate, with a yield of 97.1% and a chelation rate of 99.5%.

[0040] The filtrate after filtration was distilled under reduced pressure to remove the residual solvent, and the residue was vacuum dried to obtain the ionic liquid catalyst, which could be recycled.

[0041] By comparison, the HPLC retention time of the product in this example was consistent with that of the DL-methionine complex zinc chelate standard.

[0042] Example 2

[0043] DL-Methionine (30.0 g, 0.2 mol), zinc oxide (8.1 g, 0.1 mol) and water (200 mL) were added to a reactor, and then the ionic liquid catalyst (0.005 mol) obtained in Preparation Example 1 was slowly added, and the temperature was raised to 30 °C and stirred for reaction for 40 min. After the reaction was completed, the reaction solution was cooled to 15 °C and then filtered by suction, and the filter cake was washed with hot water. Then the obtained solid was vacuum dried at 110 °C to obtain DL-methionine complex zinc chelate, with a yield of 96.3% and a chelation rate of 99.2%.

[0044] The filtrate after filtration was distilled under reduced pressure to remove the residual solvent, and the residue was vacuum dried to obtain the ionic liquid catalyst, which could be recycled.

[0045] By comparison, the HPLC retention time of the product in this example was consistent with that of the DL-methionine complex zinc chelate standard.

[0046] Example 3

[0047] DL-methionine (3.0 kg, 20.1 mol), zinc hydroxide (1.0 kg, 10.0 mol) and water (20 L) were added to a reactor, and then the ionic liquid catalyst obtained in Preparation Example 1 (1.0 mol) was slowly added, and the temperature was raised to 40 °C and stirred for reaction for 35 min. After the reaction was completed, the reaction solution was cooled to 15 °C and then filtered by suction, and the filter cake was washed with hot water. Then the obtained solid was dried in vacuo at 110 °C to obtain DL-methionine complex zinc chelate with a yield of 96.0% and a chelation rate of 99.1%.

[0048] The filtrate after filtration was distilled under reduced pressure to remove the residual solvent, and the residue was dried in vacuo to obtain the ionic liquid catalyst, which could be recycled.

[0049] By comparison, the HPLC retention time of the product in this example was consistent with that of the DL-methionine complex zinc chelate standard.

[0050] The above embodiments are merely examples for clear illustration and not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation manners here. The obvious changes or modifications thus extended are still within the protection scope of the present invention.

Claims

1. A preparation method of a pre-nursing feed additive, characterized in that The additive is DL-methionine complex zinc, and its preparation method comprises the following steps: Using DL-methionine and zinc source as raw materials, a chelation reaction occurs in the presence of an ionic liquid catalyst to generate DL-methionine complex zinc as a pre-preservation feed additive; Among them, the structural formula of the ionic liquid catalyst is as follows: The reaction solvent is water; The zinc source is zinc hydroxide or zinc oxide.

2. The preparation method according to claim 1, characterized in that, The molar ratio of DL-methionine to zinc source is (2.0 - 2.5):1; the molar ratio of DL-methionine to ionic liquid catalyst is 1:(0.005 - 0.015).

3. The preparation method according to claim 1, characterized in that, After the reaction is completed, the reaction solution is cooled to 10 - 15 °C and then filtered by suction. The filter cake is washed with hot water, and then the obtained solid is dried in vacuum to obtain DL-methionine complex zinc.

4. The preparation method according to claim 3, characterized in that, The residual solvent in the filtrate after filtration is removed by vacuum distillation, and the residue is dried in vacuum to obtain the ionic liquid catalyst, which can be recycled.

5. The preparation method according to claim 1, wherein The reaction temperature is 20 - 50 °C, and the reaction time is 20 - 40 min.

6. The preparation method according to claim 1, wherein, Comprises the following steps: Add DL-methionine, zinc hydroxide and water into a reactor, then slowly add the ionic liquid catalyst, heat up to 35 °C and stir for reaction for 30 min; after the reaction is completed, cool the reaction solution to 15 °C and then filter by suction. The filter cake is washed with hot water, and then the obtained solid is dried in vacuum at 110 °C to obtain DL-methionine complex zinc chelate.

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