CN108689833B - Stable high-purity lactic acid preparation method - Google Patents

Stable high-purity lactic acid preparation method Download PDF

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CN108689833B
CN108689833B CN201810555080.5A CN201810555080A CN108689833B CN 108689833 B CN108689833 B CN 108689833B CN 201810555080 A CN201810555080 A CN 201810555080A CN 108689833 B CN108689833 B CN 108689833B
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lactic acid
purity
purified water
diluent
usp
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CN108689833A (en
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丁玉娟
曾飞
邵世勇
夏源
牛春霞
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ANHUI HEAL STAR PHARMACEUTICAL CO LTD
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ANHUI HEAL STAR PHARMACEUTICAL CO LTD
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
    • C07C51/42—Separation; Purification; Stabilisation; Use of additives
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
    • C07C51/42—Separation; Purification; Stabilisation; Use of additives
    • C07C51/43—Separation; Purification; Stabilisation; Use of additives by change of the physical state, e.g. crystallisation
    • C07C51/44—Separation; Purification; Stabilisation; Use of additives by change of the physical state, e.g. crystallisation by distillation
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
    • C07C51/42—Separation; Purification; Stabilisation; Use of additives
    • C07C51/50—Use of additives, e.g. for stabilisation

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Abstract

The invention discloses a stable preparation method of high-purity lactic acid, which specifically comprises the following steps: (1) feeding: adding lactic acid into a reaction kettle, uniformly stirring, then adding a diluent and a depolymerizing agent, and heating and stirring; (2) and (3) reduced pressure distillation: collecting the fraction in the step (1); (3) and (3) storage: and (3) guiding the fraction collected in the step (2) into a collecting tank containing purified water, then discharging the material into a sealed tank, sealing and storing at room temperature. The invention aims to solve the technical problem that the purity and the stability of the lactic acid are not high due to the fact that the lactic acid is polymerized by itself in the purification process.

Description

Stable high-purity lactic acid preparation method
Technical Field
The invention relates to a preparation method of lactic acid, in particular to a stable preparation method of high-purity lactic acid.
Background
Lactic acid is an important organic acid widely used in chemical industry, light industry, food and medicine. In recent years, lactic acid has been increasingly used in medicines and pharmaceutical intermediates. The self-polymer of lactic acid and the copolymer of lactic acid and other compounds are found to have biodegradability, and the application value of the self-polymer of lactic acid and the copolymer of lactic acid and other compounds is increasingly valued; the purity of the lactic acid used in the fields of chemical industry and light industry is not high; the lactic acid used for food and medicine has high requirements on the purity and stability, so much effort is put into research on the separation and purification of the lactic acid at home and abroad, but the refining and purification of the lactic acid are not solved well so far, mainly because the lactic acid can generate self polymerization in the purification process, and the polymer can well coexist with the lactic acid, so that the commercially available lactic acid contains 10-15% of lactic acid polymer regardless of food grade or medicinal grade.
Disclosure of Invention
The invention aims to provide a stable preparation method of high-purity lactic acid, and aims to solve the problem that the purity and the stability of the lactic acid are not high due to self-polymerization in the purification process.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention provides a stable preparation method of high-purity lactic acid, which comprises the following steps:
(1) feeding: adding lactic acid into a reaction kettle, uniformly stirring, then adding a diluent and a depolymerizing agent, and heating and stirring;
(2) and (3) reduced pressure distillation: collecting the lactic acid fraction;
(3) and (3) storage: guiding the fraction collected in the step (2) into a collecting tank containing purified water, then discharging the material into a sealing tank, sealing and storing at room temperature;
storage of pharmaceutical grade lactic acid: and (3) guiding the fraction collected in the step (2) into a collecting tank containing water for injection, then discharging the fraction into a sealed tank, sealing the tank and storing the fraction at room temperature, wherein the purity and stability of the medical grade lactic acid are high, and the purity and stability of the lactic acid can be improved by selecting the water for injection to replace purified water, so that the drug effect is ensured.
Preferably, the diluent in the step (1) is a high boiling point solvent, and the high boiling point solvent is preferably one of glycerol, polyethylene glycol and diglycerol or a mixture of glycerol, polyethylene glycol and diglycerol.
Preferably, the depolymerizing agent in the step (1) is an organic amine compound, and the organic amine compound is preferably tetrabutylammonium bromide.
Preferably, the lactic acid is added into the reaction kettle in the step (1), the mixture is uniformly stirred, then the diluent and the depolymerizing agent are added, and the temperature is raised to 140-150 ℃.
Preferably, the conditions for collecting the fractions in the step (2) are that the temperature is 110-120 ℃, and the pressure is-0.002-0.0015 MP a.
Preferably, in the step (3), when the concentration of the lactic acid in the collection tank reaches 10% -15%, the collection is stopped.
Preferably, the adding mass of the diluent in the step (1) is 2-3 times of the feeding amount of the lactic acid.
Preferably, the addition mass of the depolymerizing agent in the step (1) is 0.02-0.05 time of the feeding amount of the lactic acid.
The invention has the beneficial effects that: the invention aims to solve the technical problem that the purity and the stability of the lactic acid are not high due to the self-polymerization of the lactic acid in the purification process. The following aims are achieved: 1. the distillation substrate is diluted by adding a high-boiling point solvent and added with a depolymerizing agent, so that rapid polymerization of lactic acid at high temperature in the distillation process is avoided, the lactic acid is easy to polymerize under the condition of high concentration, the diluting agent is required to be added for dilution, and the depolymerizing agent is added for preventing polymerization; 2. the distilled lactic acid is immediately diluted to a concentration of 10-15% with purified water for storage, the lactic acid is stable at this concentration, and polymerization does not occur substantially during storage.
Drawings
FIG. 1 is a commercially available lactic acid purity chromatogram.
FIG. 2 is a chromatogram showing the purity of a commercially available lactic acid after purification.
FIG. 3 is a purity chromatogram of commercially available lactic acid with the addition of a diluent.
FIG. 4 is a chromatogram of the purity of commercially available lactic acid with the addition of a depolymerizing agent.
FIG. 5 is a purity chromatogram of commercially available lactic acid with diluent and depolymerizing agent added.
FIG. 6 is a purity chromatogram of distilled lactic acid immediately after being diluted with purified water to a concentration of 5% and stored for 1 month.
FIG. 7 is a purity chromatogram of distilled lactic acid immediately diluted with purified water to 5% concentration and stored for 2 months.
FIG. 8 is a purity chromatogram of distilled lactic acid immediately diluted with purified water to a concentration of 5% and stored for 3 months.
FIG. 9 is a purity chromatogram of distilled lactic acid immediately after being diluted with purified water to a concentration of 10% and stored for 1 month.
FIG. 10 is a purity chromatogram of distilled lactic acid immediately diluted with purified water to a concentration of 10% and stored for 2 months.
FIG. 11 is a purity chromatogram of distilled lactic acid immediately diluted with purified water to a concentration of 10% and stored for 3 months.
FIG. 12 is a purity chromatogram of distilled lactic acid immediately after being diluted with purified water to a concentration of 15% and stored for 1 month.
FIG. 13 is a purity chromatogram of distilled lactic acid immediately diluted with purified water to a concentration of 15% and stored for 2 months.
FIG. 14 is a purity chromatogram of distilled lactic acid immediately after being diluted with purified water to a concentration of 15% and stored for 3 months.
FIG. 15 is a purity chromatogram of distilled lactic acid immediately after being diluted with purified water to 20% concentration and stored for 1 month.
FIG. 16 is a purity chromatogram of distilled lactic acid immediately diluted with purified water to 20% concentration and stored for 2 months.
FIG. 17 is a purity chromatogram of distilled lactic acid immediately diluted with purified water to 20% concentration and stored for 3 months.
FIG. 18 is a purity chromatogram of distilled lactic acid immediately diluted with purified water to a concentration of 25% and stored for 1 month.
FIG. 19 is a purity chromatogram of distilled lactic acid immediately after being diluted with purified water to a concentration of 25% and stored for 2 months.
FIG. 20 is a purity chromatogram of distilled lactic acid immediately after being diluted with purified water to a concentration of 25% and stored for 3 months.
FIG. 21 is a purity chromatogram of distilled lactic acid immediately after being diluted with purified water to a concentration of 30% and stored for 1 month.
FIG. 22 is a purity chromatogram of distilled lactic acid immediately diluted with purified water to a concentration of 30% and stored for 2 months.
FIG. 23 is a purity chromatogram of distilled lactic acid immediately diluted with purified water to a concentration of 30% and stored for 3 months.
FIG. 24 is a comparison purity chromatogram of the effect of commercial lactic acid without diluent and depolymerizing agent, diluent only, depolymerizing agent only, and both diluent and depolymerizing agent added simultaneously.
Detailed Description
For the purpose of enhancing understanding of the present invention, the present invention will be described in further detail with reference to the accompanying drawings and examples, which are provided for the purpose of illustration only and are not intended to limit the scope of the present invention.
Example 1
50Kg of commercially available lactic acid (Henan Tian pharmaceutical Co., Ltd., lot No. 161204, purity 63.5%, commercially available lactic acid containing 10% to 15% of lactic acid polymer regardless of food grade or pharmaceutical grade, and after a storage period, the polymer increases, and the commercially available lactic acid purchased in this example and the following examples has a purity of 63.5%) was subjected to a purity chromatogram to obtain chromatogram 1, and Table 1 corresponding to chromatogram 1 is as follows:
detector A209nm
Peak number Retention time Area of Height Area% Number of theoretical plate Tailing factor Peak width of USP Degree of separation (USP)
1 4.260 2009274 270110 63.517 6865 1.309 0.206 --
2 9.804 937772 70515 29.645 12126 1.195 0.356 19.738
3 12.003 216303 4883 6.838 1664 1.128 1.177 2.869
Total of 3163348 345508 100.000
Example 2
50Kg of commercially available lactic acid (Henan Tian Cheng Yao Co., Ltd., lot No. 161204, purity 63.5%) was purified, and the purity chromatogram 2 of the purified lactic acid was as follows in Table 2:
detector A209nm
Peak number Retention time Area of Height Area% Number of theoretical plate Tailing factor Peak width of USP Degree of separation (USP)
1 4.250 2302995 308394 71.222 6735 1.318 0.207 --
2 4.703 1800 239 0.056 9125 1.500 0.197 2.238
3 9.809 928758 69894 28.723 12151 1.194 0.356 18.472
Total of 3233552 378526 100.000
Example 3
50Kg of commercially available lactic acid (manufactured by Henan Tian pharmaceutical Co., Ltd., lot No. 161204, purity 63.5%) was added to a 300L reactor, stirred uniformly, 100Kg of glycerol was added, the temperature was raised to 140 ℃, stirred, distilled under reduced pressure, and the fractions at 110 ℃ and-0.002 MP a were collected, and the collected fractions were introduced into a collection tank containing 300Kg of purified water, and when the concentration of lactic acid in the collection tank reached 12%, the collection was stopped, and the materials were discharged, sealed and stored at room temperature.
Purity chromatogram for lactic acid added diluent table 3 corresponds to the following:
detector A209nm
Peak number Retention time Area of Height Area% Number of theoretical plate Tailing factor Peak width of USP Degree of separation (USP)
1 4.211 2644396 359904 79.115 6834 1.319 0.204 --
2 9.441 698089 55637 20.885 12585 1.157 0.337 19.357
Total of 3342485 415541 100.000
Example 4
50Kg of commercially available lactic acid (manufactured by Henan Tian pharmaceutical Co., Ltd., lot No. 161204, purity 63.5%) was added to a 300L reactor, stirred uniformly, 1.32Kg of tetrabutylammonium bromide was added, the temperature was raised to 140 ℃, stirred, distilled under reduced pressure, the fractions at 110 ℃ and-0.2 MP a were collected, the collected fractions were introduced into a collection tank containing 300Kg of purified water, when the concentration of lactic acid in the collection tank reached 12%, the collection was stopped, the materials were discharged, and the mixture was sealed and stored at room temperature.
Purity chromatogram for lactic acid addition to depolymerizing agent table 4 corresponds to the following:
detector A209nm
Peak number Retention time Area of Height Area% Number of theoretical plate Tailing factor Peak width of USP Degree of separation (USP)
1 4.210 2798827 379728 86.686 6786 1.327 0.204 --
2 4.693 1322 205 0.041 9418 1.478 0.193 2.425
3 9.446 428529 26614 13.273 10438 0.966 0.370 16.876
Total of 3228679 406546 100.000
Example 5
50Kg of commercially available lactic acid (manufactured by Henan Tian pharmaceutical Co., Ltd., lot No. 161204, purity 63.5%) was added to a 300L reactor, stirred uniformly, 100Kg of glycerol and 1.32Kg of tetrabutylammonium bromide were added, the temperature was raised to 140 ℃, stirred, distilled under reduced pressure, 110 ℃ and-0.002 MP a fractions were collected, the collected fractions were introduced into a collection tank containing 300Kg of purified water, and when the concentration of lactic acid in the collection tank reached 12%, collection was stopped, the materials were discharged, and the mixture was sealed and stored at room temperature.
Purity chromatogram for lactic acid addition to diluent and depolymerizing agent 5 table 5 corresponds to:
detector A209nm
Peak number Retention time Area of Height Area% Number of theoretical plate Tailing factor Peak width of USP Degree of separation (USP)
1 4.246 3769165 477651 98.606 6081 1.378 0.218 --
2 4.767 35149 6102 0.920 13722 1.001 0.163 2.741
3 9.803 18151 1395 0.475 12523 1.186 0.350 19.625
Total of 3822466 485149 100.000
The comparison spectrum of the effect of commercially available lactic acid without diluent and depolymerizing agent, with diluent only, with depolymerizing agent only, and with diluent and depolymerizing agent added simultaneously is shown in FIG. 24. the spectrum curves of commercially available lactic acid, without diluent and depolymerizing agent, with diluent only, with depolymerizing agent only, and with diluent and depolymerizing agent added simultaneously are shown in FIG. 24 from top to bottom, and Table 6 can be obtained by combining spectrum 24, spectra 1-5, and tables 1-5 as follows:
TABLE 6 comparison of the Effect of diluent and depolymerization agent addition with No addition
Figure GDA0002844008480000051
Note: "+" represents addition and "-" represents no addition
As can be seen from Table 6, when only one of the diluent and the depolymerization agent was added, the purity was higher than that when neither of the diluent and the depolymerization agent was added, and when both were added, the purity was 98.60%, and it was found that lactic acid obtained by adding the diluent and the depolymerization agent to commercially available lactic acid and purifying it by distillation under reduced pressure and immediately diluting and storing the distilled high-purity lactic acid had a high purity, and it was satisfactory for use of lactic acid in foods and medicines.
The peaks corresponding to the purity chromatograms of the distilled lactic acid immediately diluted with purified water to a concentration of 5% to 30% stored for various times are shown below:
1. the peaks corresponding to the purity chromatogram of 1 month of storage of the distilled lactic acid immediately diluted to 5% concentration with purified water are shown in Table 7 below:
PDACh1209nm
peak number Retention time Area of Height Area% Number of theoretical plate Tailing factor Peak width of USP Degree of separation (USP)
1 4.193 2953422 434805 98.076 7340 1.363 0.196 --
2 9.461 57947 4790 1.924 13199 1.122 0.329 20.061
Total of 3011369 439595 100.000
2. The peaks corresponding to the purity chromatogram 7 of the distilled lactic acid immediately diluted with purified water to 5% concentration and stored for 2 months are shown in Table 8 below:
detector A209nm
Peak number Retention time Area of Height Area% Number of theoretical plate Tailing factor Peak width of USP Degree of separation (USP)
1 4.113 2785448 344051 97.301 5632 1.515 0.219 --
2 4.647 10971 2019 0.383 13554 1.078 0.160 2.818
3 9.122 66304 5176 2.316 11395 1.187 0.342 17.850
Total of 2862723 351246 100.000
3. The peaks corresponding to the purity chromatogram 8 of the distilled lactic acid immediately diluted with purified water to 5% concentration and stored for 3 months are shown in Table 9 below:
PDACh1209nm
peak number Retention time Area of Height Area% Number of theoretical plate Tailing factor Peak width of USP Degree of separation (USP)
1 4.134 2994108 458764 96.939 7685 1.379 0.189 --
2 8.875 94534 8421 3.061 13215 1.136 0.309 19.059
Total of 3088642 467186 100.000
4. The peaks in the purity chromatogram of 1 month of storage of the distilled lactic acid immediately diluted to 10% with purified water are shown in Table 10 below:
PDACh120gnm
peak number Retention time Area of Height Area% Number of theoretical plate Tailing factor Peak width of USP Degree of separation (USP)
1 4.131 1631444 238707 99.053 6909 1.312 0.199 --
2 8.922 15599 1325 0.947 12125 1.075 0.324 18.324
Total of 1647042 240032 100.000
5. The peaks corresponding to the purity chromatogram 10 of the distilled lactic acid immediately diluted with purified water to a concentration of 10% stored for 2 months are shown in Table 11 below:
PDACh1209nm
peak number Retention time Area of Height Area% Number of theoretical plate Tailing factor Peak width of USP Degree of separation (USP)
1 4.192 3298328 482038 98.870 7248 1.382 0.197 --
2 9.465 37685 3124 1.130 13251 1.135 0.329 20.057
Total of 3336014 485162 100.000
6. The peaks in the purity chromatogram of 3 months of storage of the distilled lactic acid immediately diluted with purified water to a concentration of 10% are shown in Table 12 below:
PDACh1209nm
peak number Retention time Area of Height Area% Number of theoretical plate Tailing factor Peak width of USP Degree of separation (USP)
1 4.132 1567441 229407 98.300 6952 1.310 0.198 --
2 8.905 27105 2300 1.700 12120 1.142 0.324 18.296
Total of 1594547 231707 100.000
7. The peaks in the purity chromatogram 12 of the distilled lactic acid immediately diluted with purified water to 15% concentration and stored for 1 month are shown in Table 13 below:
detector A209nm
Peak number Retention time Area of Height Area% Number of theoretical plate Tailing factor Peak width of USP Degree of separation (USP)
1 4.115 2881438 350514 98.336 5493 1.531 0.222 --
2 4.643 7423 980 0.253 10700 2.307 0.180 2.628
3 9.152 41332 3204 1.411 11279 1.192 0.345 17.202
Total of 2930192 354697 100.000
8. The peaks in the purity chromatogram 13 of the distilled lactic acid immediately diluted with purified water to 15% concentration and stored for 2 months are shown in Table 14 below:
PDACh1209nm
peak number Retention time Area of Height Area% Number of theoretical plate Tailing factor Peak width of USP Degree of separation (USP)
1 4.131 3175954 485439 98.769 7524 1.391 0.191 --
2 8.828 39587 3572 1.231 13442 1.123 0.305 18.974
Total of 3215542 489011 100.000
9. The peaks in the purity chromatogram 14 of the distilled lactic acid immediately diluted with purified water to 15% concentration and stored for 3 months are shown in Table 15 below:
PDACh1209nm
peak number Retention time Area of Height Area% Number of theoretical plate Tailing factor Peak width of USP Degree of separation (USP)
1 4.141 3108911 474479 97.938 7500 1.382 0.191 --
2 8.869 65455 5827 2.062 13281 1.133 0.308 18.946
Total of 3174366 480306 100.000
10. The peaks in the purity chromatogram 15 of the distilled lactic acid immediately diluted with purified water to 20% concentration and stored for 1 month are shown in Table 16 below:
PDACh1209nm
peak number Retention time Area of Height Area% Number of theoretical plate Tailing factor Peak width of USP Degree of separation (USP)
1 4.140 1537255 225899 97.371 7110 1.310 0.196 --
2 8.905 41498 3509 2.629 11997 1.121 0.325 18.272
Total of 1578752 229408 100.000
11. The peaks in the purity chromatogram 16 of the distilled lactic acid immediately diluted with purified water to 20% concentration and stored for 2 months are shown in Table 17 below:
detector A209nm
Peak number Retention time Area of Height Area% Number of theoretical plate Tailing factor Peak width of USP Degree of separation (USP)
1 4.123 3272913 451017 97.102 6684 1.392 0.202 --
2 4.639 15072 2503 0.447 11418 1.064 0.174 2.748
3 9.236 83609 6706 2.451 12520 1.192 0.330 18.249
Total of 3370594 460227 100.000
12. The peaks in the purity chromatogram 17 of the distilled lactic acid immediately diluted with purified water to 20% concentration and stored for 3 months are shown in Table 18 below:
detector A209nm
Peak number Retention time Area of Height Area% Number of theoretical plate Tailing factor Peak width of USP Degree of separation (USP)
1 4.126 3051056 422826 95.687 6748 1.383 0.201 --
2 4.639 7712 1252 0.242 10824 1.091 0.178 2.706
3 9.250 129815 10580 4.071 12583 1.192 0.330 18.145
Total of 3188583 434657 100.000
13. The peaks in the purity chromatogram 18 of the distilled lactic acid immediately diluted with purified water to a concentration of 25% and stored for 1 month are shown in Table 19 below:
detector A209nm
Peak number Retention time Area of Height Area% Number of theoretical plate Tailing factor Peak width of USP Degree of separation (USP)
1 4.125 2947321 408629 96.279 6755 1.379 0.201 --
2 4.640 11817 1903 0.386 10728 1.065 0.179 2.711
3 9.254 102094 8266 3.335 12583 1.192 0.330 18.123
Total of 3061232 418799 100.000
14. The peak table 20 corresponding to the purity chromatogram 19 of the distilled lactic acid immediately diluted with purified water to a concentration of 25% stored for 2 months is as follows:
detector A209nm
Peak number Retention time Area of Height Area% Number of theoretical plate Tailing factor Peak width of USP Degree of separation (USP)
1 4.125 2708822 375997 94.862 6771 1.370 0.201 --
2 4.635 6580 1074 0.230 10759 1.084 0.179 2.686
3 9.234 140137 11381 4.908 12514 1.196 0.330 18.075
Total of 2855539 388452 100.000
15. The peaks in the purity chromatogram 20 of the distilled lactic acid immediately diluted with purified water to a concentration of 25% and stored for 3 months are shown in Table 21 below:
detector A209nm
Peak number Retention time Area of Height Area% Number of theoretical plate Tailing factor Peak width of USP Degree of separation (USP)
1 4.122 3059748 422184 94.274 6705 1.387 0.201 --
2 4.639 9146 1485 0.282 10856 1.062 0.178 2.727
3 9.289 176696 14222 5.444 12462 1.199 0.333 18.199
Total of 3245589 437891 100.000
16. The peaks in the purity chromatogram 21 of the distilled lactic acid immediately diluted with purified water to 30% concentration and stored for 1 month are shown in Table 22 below:
detector A209nm
Peak number Retention time Area of Height Area% Number of theoretical plate Tailing factor Peak width of USP Degree of separation (USP)
1 4.124 3052086 421254 96.215 6699 1.383 0.202 --
2 4.637 8969 1459 0.283 10941 1.087 0.177 2.705
3 9.236 111084 9031 3.502 12528 1.192 0.330 18.128
Total of 3172138 431744 100.000
17. The peaks in the purity chromatogram 22 of the distilled lactic acid immediately diluted with purified water to 30% concentration and stored for 2 months are shown in Table 23 below:
detector A209nm
Peak number Retention time Area of Height Area% Number of theoretical plate Tailing factor Peak width of USP Degree of separation (USP)
1 4.130 2696144 374192 94.199 6806 1.373 0.200 --
2 4.641 5810 948 0.203 10836 1.101 0.178 2.695
3 9.246 160214 13031 5.598 12584 1.196 0.330 18.133
Total of 2862168 388171 100.000
18. The peak table 24 corresponding to the purity chromatogram 23 of the distilled lactic acid immediately diluted with purified water to a concentration of 30% stored for 3 months is as follows:
detector A209nm
Peak number Retention time Area of Height Area% Number of theoretical plate Tailing factor Peak width of USP Degree of separation (USP)
1 4.122 2991473 414077 93.995 6745 1.384 0.201 --
2 4.638 6590 1068 0.207 10743 1.083 0.179 2.718
3 9.274 184520 14896 5.798 12492 1.200 0.332 18.151
Total of 3182583 430041 100.000
From peak tables 7-24 and spectra 6-23, the following table 25 can be obtained:
TABLE 25 comparison of the stability of lactic acid at different concentrations
Figure GDA0002844008480000091
As can be seen from the above table, lactic acid at a concentration of 10% to 15% is storage stable and substantially no polymerization occurs during storage.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.

Claims (6)

1. A stable preparation method of high-purity lactic acid is characterized by comprising the following steps:
(1) feeding: adding lactic acid into a reaction kettle, uniformly stirring, then adding a diluent and a depolymerizing agent, and heating and stirring;
(2) and (3) reduced pressure distillation: collecting the lactic acid fraction;
(3) and (3) storage: guiding the fraction collected in the step (2) into a collecting tank containing purified water, then discharging the material into a sealing tank, sealing and storing at room temperature;
the diluent in the step (1) is a high-boiling point solvent, and the high-boiling point solvent is one of glycerol, polyethylene glycol and diglycerol or a mixture of glycerol, polyethylene glycol and diglycerol;
the depolymerizing agent in the step (1) is an organic amine compound, and the organic amine compound is tetrabutylammonium bromide.
2. The stable high purity lactic acid production method according to claim 1, characterized in that: adding lactic acid into a reaction kettle, uniformly stirring, then adding a diluent and a depolymerizing agent, and heating to 140-150 ℃.
3. The stable high purity lactic acid production method according to claim 1, characterized in that: the conditions for collecting the fractions in the step (2) are that the temperature is 110-120 ℃, and the pressure is-0.002-0.0015 MPa.
4. The stable high purity lactic acid production method according to claim 1, characterized in that: and (4) stopping collecting when the concentration of the lactic acid in the collecting tank reaches 10-15% in the step (3).
5. The stable high purity lactic acid production method according to claim 1, characterized in that: the adding mass of the diluent in the step (1) is 2-3 times of the feeding amount of the lactic acid.
6. The stable high purity lactic acid production method according to claim 1, characterized in that: the adding mass of the depolymerizing agent in the step (1) is 0.02-0.05 time of the feeding amount of the lactic acid.
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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0986532A1 (en) * 1997-06-06 2000-03-22 Brussels Biotech Method for purifying lactic acid
CN1287113A (en) * 1999-06-28 2001-03-14 罗姆和哈斯公司 Process for producing (methyl) propenoic acid
CN101495440A (en) * 2006-08-02 2009-07-29 株式会社吴羽 Method for purifying hydroxycarboxylic acid, method for producing cyclic ester, and method for producing polyhydroxycarboxylic acid
CN107098808A (en) * 2017-05-05 2017-08-29 湖北壮美生物科技有限公司 The preparation method and process units of a kind of high-purity, high content normal temperature not crystalline lactic acid product

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0986532A1 (en) * 1997-06-06 2000-03-22 Brussels Biotech Method for purifying lactic acid
CN1287113A (en) * 1999-06-28 2001-03-14 罗姆和哈斯公司 Process for producing (methyl) propenoic acid
CN101495440A (en) * 2006-08-02 2009-07-29 株式会社吴羽 Method for purifying hydroxycarboxylic acid, method for producing cyclic ester, and method for producing polyhydroxycarboxylic acid
CN107098808A (en) * 2017-05-05 2017-08-29 湖北壮美生物科技有限公司 The preparation method and process units of a kind of high-purity, high content normal temperature not crystalline lactic acid product

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