The method of synthesizing theanine

Abstract

A method for synthesizing theanine comprises the following steps of: (1) suspending glutamic acid in C1-6 alcohol, performing a catalytic reaction under acidic condition, neutralizing to neutral by the use of an organic base, followed by centrifugation to obtain glutamic acid-5-ester; (2) suspending glutamic acid-5-ester in C1-4 alcohol, adding ethylamine for a reaction to obtain a theanine ethylamine solution; recovering ethylamine and ethanol by the use of the theanine ethylamine solution, followed by pressure reduction, condensation and crystallization, separating and collecting crystals; (3) dissolving the crystals in water, followed by refining and filtering, adding edible alcohol for crystallization, separating and collecting crystals to obtain theanine. High-purity L-theanine and D-theanine can be obtained by the adoption of the synthesis method provided by the invention. The corresponding isomer of the prepared theanine is less than 0.02%. The contents of two structures contained in the obtained high-purity DL-theanine are similar. In addition, the production technology of theanine is simple and short; the whole reaction process is carried out in normal pressure; in comparison with synthesis methods which require pressure, the synthesis method provided by the invention is safer and more environment-friendly to life and environment, is simple in operation, results in high yield, requires low cost, and has no high requirement on equipment.

Description

technical field [0001] The invention relates to a method for synthesizing amino acids, in particular to a method for synthesizing theanine. Background technique [0002] Tea is rich in a variety of amino acids, among which L-theanine (L-thiamine) has edible and health functions and is beneficial to the human body, while free D-theanine has many side effects on the human body. People rely on drinking tea to ingest L-theanine, but the L-theanine contained in tea is very limited, so a method of artificially synthesizing L-theanine was invented in order to obtain more high-purity L-tea amino acid, and claim that it is very low in D-theanine. [0003] At present, there are three main methods for artificially synthesizing L-theanine: [0004] Method 1, using L-glutamine and ethylamine derivatives to mix and then use glutaminase to convert and synthesize (CN 1977047A), this method can avoid the generation of D-theanine, but the process is long, the operation is complicated, and t...

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Problems solved by technology

[0004]Method 1, use L-glutamine and ethylamine derivatives to mix and then use glutaminase to convert and synthesize (CN 1977047A), this method can avoid D- The production of theanine, but the process is long, the operation is complicated, there are many types of products, it is not easy to separate, and the equipment requirements are high

[0005] Method 2, using ethylamine and L-pyroglutamic acid to react and synthesize (CN 1706816 A, CN 1690046A). The total yield of this method is higher, but it needs to use Anhydrous ethylamine and pressure equipment are used, which cause high equipment requirements for industrial production, and there is a greater risk to life and the environment, and it is easy to bring D-theanine to affect the quality of L-theanine

[0006] Method 3: Use amino-protected L-glutamic acid-5-ester to react with ethylamine to synthesize amino-protected theanine and deprotect theanine to obtain theanine acid (CN1789237), which can avoid bringing D-theanine under good control, but also has the disadvantages of long process and high cost

[0007] In addition, D-theanine is used to synthesize polypeptides, and D-theanine and DL-theanine are also important raw materials for scientific research and fine chemical synthesis. The demand is increasing day by day, so far, there are few reports on the artificial synthesis of D-theanine and DL-theanine

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