The industrial production process and quality control of N6-Cbz-L-lysine are as follows:
I. Industrial Production Process
Raw Material Preparation: The main raw materials are L-lysine and benzyl chloroformate. L-lysine is usually purchased as a hydrochloride salt and requires pretreatment, such as neutralization with an alkali solution to an appropriate pH to convert it into free L-lysine. Benzyl chloroformate must ensure its purity and stability, stored in a cool, dry place, avoiding contact with water and air to prevent hydrolysis and deterioration.
Reaction Process: Add the pretreated L-lysine solution to the reaction kettle, usually using water or an organic solvent (such as dichloromethane, N,N-dimethylformamide, etc.) as the solvent. Cool the reaction kettle to a certain temperature, generally 0°C to 5°C, and then slowly add benzyl chloroformate dropwise. At the same time, add an appropriate amount of alkali (such as sodium carbonate, potassium carbonate, or triethylamine, etc.) as an acid-binding agent to neutralize the hydrogen chloride generated by the reaction, so that the reaction proceeds in a direction conducive to the formation of N6-Cbz-L-lysine. After the dropwise addition is completed, continue stirring the reaction at low temperature for several hours. The specific reaction time is determined by monitoring the reaction progress through methods such as thin-layer chromatography (TLC) or high-performance liquid chromatography (HPLC). Generally, the reaction time is 4-8 hours.
Post-treatment: After the reaction is completed, pour the reaction solution into a separatory funnel, add an appropriate amount of water and organic solvent for extraction and liquid separation. Wash the organic phase with saturated brine to remove residual water-soluble impurities, then dry it with anhydrous sodium sulfate or magnesium sulfate, filter to remove the desiccant, and distill off the organic solvent under reduced pressure to obtain the crude product. Dissolve the crude product in an appropriate amount of solvent, such as ethanol, methanol, or a water-ethanol mixed solvent, etc., then add activated carbon for decolorization, and filter to remove the activated carbon. Cool the filtrate to a low temperature to precipitate N6-Cbz-L-lysine crystals, filter to obtain the crystals, wash the crystals with a cold solvent to remove surface impurities, and finally dry them in a vacuum drying oven to obtain the finished product.
II. Quality Control
Raw Material Quality Control: Strictly inspect the quality of L-lysine and benzyl chloroformate. For L-lysine, detect its purity, optical rotation, moisture content, heavy metal content and other indicators to ensure compliance with pharmaceutical or industrial standards. For benzyl chloroformate, detect its purity, acidity, moisture and related substances to ensure the stability and consistency of the raw material quality.
Process Quality Control: During the reaction process, strictly control parameters such as reaction temperature, pH value, reaction time, and the feeding ratio of raw materials. Regularly sample and detect the reaction solution, and use methods such as TLC and HPLC to monitor the reaction progress to ensure the reaction is complete and avoid side reactions. At the same time, monitor and record process parameters such as the stirring speed and pressure of the reaction kettle to ensure process stability. During the post-treatment process, control the operating conditions of extraction, washing, drying, crystallization, etc., to ensure the yield and purity of the product. For example, during the crystallization process, control the cooling rate, stirring speed, and the amount of solvent to obtain crystals with uniform particle size and high purity.
Finished Product Quality Control: Conduct a comprehensive quality inspection on the final product, including appearance, properties (should be a white to off-white powder), melting point (usually around 259°C, decomposition), specific optical rotation, purity (generally requiring a purity ≥98% or higher, determined by HPLC method), related substances (using HPLC or other suitable methods to detect impurity content), moisture content (usually requiring moisture ≤0.5% or according to specific product requirements), heavy metal content (should comply with relevant standards, such as the content of heavy metals such as lead, mercury, and cadmium not exceeding parts per million) and other indicators. At the same time, conduct a stability study on the product, place the product under different temperature and humidity conditions, and regularly detect its quality changes to determine the validity period and storage conditions of the product.
