Method for synthesizing D-p-hydroxyphenylglycine methyl ester
A technology of p-hydroxyphenylglycine methyl ester and p-hydroxyphenylglycine, applied in the field of synthesizing D-p-hydroxyphenylglycine methyl ester, can solve the problem of low yield
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[0018] The D-p-hydroxyphenylglycine resolving agent salt can be obtained commercially, or can be prepared according to various methods known to those skilled in the art. According to a preferred embodiment of the present invention, the D-p-hydroxyphenylglycine resolving agent salt is obtained by mixing DL-p-hydroxyphenylglycine and sodium phenylethanesulfonate in hydrochloric acid and salicylaldehyde at 100-110°C. Reaction in the presence of 8-12 hours to obtain. In the preparation process, relative to 100 parts by weight of sodium phenylethanesulfonate, the amount of DL-p-hydroxyphenylglycine can be 75-90 parts by weight, and the amount of hydrochloric acid can be 50-60 parts by weight, The amount of the salicylic acid can be 2-3 parts by weight; preferably, relative to 100 parts by weight of sodium phenylethanesulfonate, the amount of DL-p-hydroxyphenylglycine is 80-85 parts by weight, the The amount of hydrochloric acid is 53-56 parts by weight, and the amount of salicylal...
specific Embodiment approach
[0026] In the present invention, the method for removing salicylaldehyde in step (3) is not particularly limited, and various existing methods can be used to carry out. According to a specific embodiment of the present invention, salicylaldehyde is removed by the following method: add water to the reaction product obtained after the reaction, and then evaporate water to entrain and remove salicylaldehyde. The specific operation is a technology in the art It is well-known to the personnel and will not be described in detail here.
[0027] The present invention will be described in detail below by way of examples.
[0028] In the following examples and comparative examples:
[0029] In step (1), the yield of D-p-hydroxyphenylglycine methyl phenylethanesulfonate=the actual output of D-p-hydroxyphenylglycine methyl phenylethanesulfonate ÷ D-p-hydroxyphenylglycine methyl benzene Theoretical yield of ethyl ethanesulfonate × 100%.
[0030] The yield of D-p-hydroxyphenylglycine methy...
Embodiment 1
[0032] This embodiment is used to illustrate the method for synthesizing D-p-hydroxyphenylglycine methyl ester provided by the present invention.
[0033] (1) Esterification:
[0034] Add 11700mL of methanol into a 30L glass reactor, start stirring, take 6000g of D-p-hydroxyphenylglycine phenylethanesulfonate (also known as DD salt, the same below) into the glass reactor, and control the temperature below 25 2230 g of thionyl chloride was added dropwise at °C. After the dropwise addition of the thionyl chloride, the temperature was raised to a reflux state, and the reflux was maintained for 3 hours. After the esterification reaction was completed, an esterification liquid was obtained. Detected by HPLC, the yield of D-p-hydroxyphenylglycine methyl phenylethanesulfonate in the esterified solution was 98.5%.
[0035] (2) Neutralization:
[0036] Add water 2000mL and D-hydroxyphenylglycine methyl ester 50g (as seed crystal) in 3L glass reaction bottle, control temperature at 1...
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