Background technology
Ascorbic acid magnesium phosphate is a vitamin C derivative. Derivating the 2-position hydroxyl group into a phosphate ester can improve the stability of vitamin C. The resulting derivative is widely used in the body. The existing phosphatase can regenerate vitamin C after hydrolysis, so it has become the main component of feed additives, food fortifiers and high-end cosmetics whitening, and is a valuable fine chemical.
So far, there are two main methods for phosphorylation of vitamin C: one is phosphorylation of phosphorus oxychloride (such as European patents 388869 and 582924, U.S. patent 4179445, Japanese patent No. 60-69079 etc.), using vitamin C as raw material, the hydroxyl groups on the 5th and 6th carbons are protected before esterification, that is, vitamin C first undergoes a ketal reaction with acetone to generate 5,6-oxyisopropylidene- L-ascorbic acid (5,6-0 – isopropylidene-L-ascorbic acid), then dissolve it with pyridine solution, adjust the pH value with KOH, dropwise add phosphorus oxychloride to react, evaporate the pyridine, remove salt several times, concentrate, and then Cationic resin exchange, collecting the eluent, adding MgO for reaction, and finally the low carbon alcohol crystallization, filtration and drying are completed. The main product is L-ascorbic acid-2-monophosphate, and the by-products are mainly L-ascorbic acid-3-phosphate, 2-pyrophosphate and di(ascorbic acid)-2,2′-diphosphate.
The reaction product requires complicated purification processes, and the entire reaction mixture cannot be dried using a simple method. The second method is to use phosphate for phosphorylation, such as the methods of US patents 4647672 and 5110950. The main product obtained is L-ascorbic acid-2-polyphosphate. If sodium trimetaphosphate is used, the product is L-ascorbic acid-2-polyphosphate. 2-triphosphate, but also contains a certain proportion of L-ascorbic acid-2-monophosphate.
The former can be degraded to monophosphate by excess alkali, and the ratio depends on the stoichiometric ratio of the starting materials and the specific reaction conditions. It is not easy to purify L-ascorbic acid-2-monophosphate from the mixture, and the inorganic salt residue in the product is often very high. Although this method has a short synthesis route, there are many by-products, it is difficult to separate and purify the product, and the overall product yield is low. The synthesis process of traditional magnesium vitamin C phosphate is complex, contains many impurities, and uses organic solutions such as acetone, which causes damage to the environment.
Content of the invention
The purpose of the present invention is to overcome the shortcomings in the existing technology and provide a vitamin C phosphate with simple process, convenient operation, low cost and high yield. A method for preparing magnesium. This method does not use organic solvents during the preparation process, has simple post-processing, does not cause environmental pollution, and the prepared product has high purity.
According to the technical solution provided by the present invention, a method for preparing magnesium vitamin C phosphate is characterized by including the following process steps:
(1) Mix vitamin C, anhydrous Calcium chloride and deionized water are added into the reaction kettle at a temperature of -10~20°C according to the mass ratio of 1: (0.08~0.4): (1~5), stir for 2~3 hours, and then add dropwise at a concentration of 30~ 70% sodium hydroxide aqueous solution, adjust the pH to 5~10.5, then add 1~2.5 times the amount of sodium trimetaphosphate of vitamin C, keep the temperature at 25~45°C, react for 2~6 hours, the resulting reactant is Vitamin C ester calcium;
(2) Add vitamin C ester calcium into the barrel cleaner to wash with water, and then use sulfuric acid to adjust the pH to 1.5~3.5. The obtained reactant is vitamin C phosphate;
(3) Pass the vitamin C phosphate through the rolled nanofiltration membrane filter for nanofiltration membrane filtration. The temperature at the entrance of the rolled nanofiltration membrane filter is 120~140°C. The rolled nanofiltration membrane The temperature at the filter outlet is 30~50°C; the nanofiltration membrane has a nanometer pore size, and the molecular weight cutoff of the nanofiltration membrane is 500~1500. The rolled nanofiltration membrane filter has a high removal rate of inorganic salts. The removal rate is 90~98%;
(4) Add the filtrate filtered in step (3) into the reaction kettle, pass through the weakly basic anion exchange resin, and use 0.05M hydrochloric acid and 0.5M~1.5 in sequence. Elute with M hydrochloric acid, collect the eluted part, adjust the pH of the eluted part to 7~11 with magnesium oxide under constant stirring, and the obtained reactant is vitamin C magnesium phosphate;
(5) Add the vitamin Magnesium C phosphate is filtered through an activated carbon filter to remove the precipitate. The filtrate is concentrated under reduced pressure at 30°C to one-fifth of the original volume. Add ethanol with a volume of 3 to 6 times the concentrated filtrate and a content of 95%, and then pass it through a spray dryer. Drying, the drying temperature is 140~160°C, the drying time is 30~40min, and the finished product of magnesium vitamin C phosphate is obtained.
Compared with the prior art, the present invention has the following advantages:
The phosphoric acid esterification reaction of the present invention is carried out in a water solvent without using organic solvents. The whole process is simple and not only speeds up It improves the phosphate esterification reaction speed, shortens the reaction time, simplifies the operating procedures, and is environmentally safe; it adopts a new nanofiltration membrane process, which has high impurity removal efficiency. The purity of the finished magnesium vitamin C phosphate is over 95% and has good stability.
Specific embodiments:
The present invention will be further described below in conjunction with specific examples.
A method for preparing magnesium vitamin C phosphate, including the following process steps:
(1) Mix 110Kg vitamin C, 8.8Kg anhydrous calcium chloride, and 110Kg deionized water Add it to a 500L reaction kettle with a temperature of -10°C, stir for 2 hours, then add dropwise 0% sodium hydroxide aqueous solution with a concentration of 3 color paste manufacturers, adjust the pH to 5, then add 110Kg of sodium trimetaphosphate, and keep the temperature at 25 °C, react for 2 hours, and the reactant obtained is vitamin C ester calcium;
(2) Add vitamin C ester calcium into a 500L barrel cleaner to wash with water, and then use sulfuric acid to adjust the pH to 1.5. The obtained reactant is vitamin C phosphate;
(3) Treat vitamin C phosphate throughThe roll-type nanofiltration membrane filter performs nanofiltration membrane filtration. The temperature of the roll-type nanofiltration membrane filter inlet is 120°C, and the temperature of the roll-type nanofiltration membrane filter outlet is 30°C; the nanofiltration membrane has a nanometer-scale pore size. , the molecular weight cutoff of the nanofiltration membrane is 500, and the rolled nanofiltration membrane filter has a high removal rate of inorganic salts, with a removal rate of 90%
(4) Filter step (3) The obtained filtrate was added to a 500L reaction kettle, passed through a weakly basic anion exchange resin, and eluted with 0.05M hydrochloric acid and 0.5M hydrochloric acid in sequence. The eluted part was collected, and the eluted part was eluted with magnesium oxide under constant stirring. Adjust the pH to 7, and the obtained reactant is magnesium vitamin C phosphate;
(5) Filter the magnesium vitamin C phosphate through an activated carbon filter to remove the precipitate, and the filtrate is concentrated under reduced pressure at 30°C to its original content. One-fifth of the volume, add 3 times the volume of 95% ethanol to the concentrated filtrate, and then dry it through a spray dryer at a drying temperature of 140°C and a drying time of 30 minutes to obtain white magnesium vitamin C phosphate 79.85 KG, magnesium vitamin C phosphate content 97.75%.
