Preparation method of (S)-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid
A technology of tetrahydroisoquinoline and carboxylic acid, applied in the direction of organic chemistry and the like, can solve the problems of difficult treatment of waste hydrobromic acid, difficult to achieve results, increase production cost, etc., to improve the utilization rate of raw materials, improve conversion rate, reaction The effect of fewer steps
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Embodiment 1
[0017] Under airtight conditions, add 200 parts by mass of L-phenylalanine and 45 parts by mass of paraformaldehyde to 1000 parts by mass of concentrated hydrochloric acid (about 37% in mass concentration), heat and stir at 50°C for 5 hours, cool to 10°C, and stir 1h, filter. Add the filter cake into water, heat to 60°C, add 200g / L NaOH solution dropwise until the pH is 8, stir for 1h, cool down to 10°C, stir for 1h, filter with suction, wash with water, and dry to obtain (S)-1,2 ,3,4-Tetrahydroisoquinoline-3-carboxylic acid solid.
[0018] The filtrate was fed with hydrogen chloride gas until it was saturated, the above steps were repeated, and it was reused 4 times, and the yield could still reach more than 90%.
Embodiment 2
[0020] Under airtight conditions, 180 parts by mass of L-phenylalanine and 40 parts by mass of paraformaldehyde were sequentially added to 900 parts by mass of concentrated hydrochloric acid, heated and stirred at 65°C for 10 hours, cooled to 25°C, and stirred for 3 hours. Add the filter cake into water, heat to 80°C, add dropwise 300g / L NaOH solution until the pH is 7.8, stir for 1.5h, cool down to 25°C, stir for 3h, filter with suction, and wash with water. Dry to obtain (S)-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid solid.
[0021] The filtrate was fed with hydrogen chloride gas until it was saturated, the above steps were repeated, and it was reused 4 times, and the yield could still reach more than 90%.
Embodiment 3
[0023] Under airtight conditions, 220 parts by mass of L-phenylalanine and 50 parts by mass of paraformaldehyde were sequentially added to 1100 parts by mass of concentrated hydrochloric acid, heated and stirred at 60°C for 7 hours, cooled to 20°C, stirred for 2 hours, and filtered. Add the filter cake into water, heat to 70°C, add 250g / L NaOH solution dropwise until the pH is 8.2, stir for 1.2h, cool down to 20°C, stir for 2h, filter with suction, wash with water, and dry to obtain (S)-1 ,2,3,4-Tetrahydroisoquinoline-3-carboxylic acid solid.
[0024] The filtrate was fed with hydrogen chloride gas until it was saturated, the above steps were repeated, and it was reused 4 times, and the yield could still reach more than 90%.
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