Method for producing terminal carboxyl group-containing polyethylene glycol and method for producing activated polyethylene glycol
A technology of polyethylene glycol and terminal carboxyl group is applied in the field of preparation of activated polyethylene glycol, which can solve the problems of low purification treatment and difficulty in removing terminal hydroxyl compounds.
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[0102] In the production method of the present invention, the carboxyl group-containing PEG having high carboxyl group purity can be obtained in good yield by allowing water to exist in the system during the etherification reaction, which is generally a water-deprivation reaction.
[0103] The reaction temperature in (step 1) is not particularly limited as long as it is a temperature at which polyethylene glycol having a hydroxyl group as a raw material is dissolved in an aprotic solvent. However, when the reaction temperature is low, the target etherification reaction of polyethylene glycol with the compound represented by formula (1) (hereinafter referred to as reaction A) slows down, and a systemic side reaction that occurs simultaneously with the main reaction may occur. The etherification reaction of water in and the compound represented by the formula (1) (hereinafter referred to as reaction B), makes it possible to hinder the target reaction A. On the other hand, when t...
Embodiment 1
[0128] After putting 101 g of linear PEG (product from NOF, MEH-50H) with a molecular weight of 5000, a hydroxyl group at one end and a methoxyl group at the other end, and 1800 g of toluene into a 5 L four-necked flask, the temperature was raised under a nitrogen atmosphere and the All dissolved at 45°C. The water content in the system was adjusted and confirmed to be 318 ppm (amount of water relative to KOH: 9.42 meq). After adding 200 g of KOH (product of Toa Kogyo, flakes) to the solution, 89.2 g of ethyl 6-bromohexanoate (product of Tokyo Chemical Industry Co., Ltd.) was added dropwise at a solution temperature of 40°C. After the dropwise addition was completed, the mixture was aged at 40°C for 1.5 hours. After the aging was completed, 700 g of water was added, the temperature was raised to 70° C., and the mixture was stirred for 1 hour for hydrolysis. After hydrolysis, layering was performed under the acidic condition of hydrochloric acid, and then the terminal carboxy...
Embodiment 2
[0131] After putting 41 g of linear polyethylene glycol (product from NOF, MEH-20T) with a molecular weight of 20000, a hydroxyl group at one end and a methoxyl group at the other end, and 323 g of toluene into a 1 L four-necked flask and all under a nitrogen atmosphere at After refluxing at 110±5° C. for 1 h, the water content in the system was adjusted to 298 ppm (the amount of water relative to KOH: 5.11 meq). 82 g of KOH was added to the solution after adjusting the water content, and 9.15 g of ethyl 6-bromohexanoate was added dropwise at 40° C. using a dropping funnel. After the dropwise addition was completed, the mixture was aged at 40°C for 4 hours. After the aging was completed, 287 g of water was added, the temperature was raised to 70° C., and hydrolysis was carried out for 1 hour. Thereafter, terminal carboxylic acid-containing polyethylene glycol was obtained by the same operation as in Example 1.
[0132] The purity of the obtained terminal carboxyl group-conta...
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