Preparation method of 4-hydroxy-nitrostyrene_Industrial additives

Background and overview^[1]

4-Hydroxy-nitrostyrene is an important intermediate raw material for the synthesis of pharmaceutical products. The existing preparation methods of 4-hydroxy-β-nitrostyrene have low yields, complex synthesis processes, and unstable yields. It is necessary to invent a new preparation method to overcome the shortcomings of the existing technology in order to achieve energy saving. , environmental protection and green purpose.

Preparation^[1]

Method 1: Preparation of 4-hydroxy-nitrostyrene: Add 1221 mg of p-hydroxybenzaldehyde to the reactor, add 30 ml of methanol, stir, add 671 mg of nitromethane at room temperature, and then take an ice bath Stir for 20 minutes, then add 848 mg of ammonium acetate, and then stir at room temperature for 4 hours. The reaction solution gradually turns yellow. Leave to stand for 5 hours and filter out the yellow solid. It was then recrystallized in methanol, filtered, and dried under vacuum to obtain compound 4-hydroxy-nitrostyrene with a yield of 91.1%.

Method 2: The synthesis method of 4-hydroxy-nitrostyrene is prepared by Knoevenagel reaction using p-hydroxybenzaldehyde and nitromethane as raw materials, ammonium acetate as catalyst, and glacial acetic acid as solvent.

The synthesis method includes the following steps:

a)． Mix glacial acetic acid and anhydrous hydroquinone in a material ratio of 1:0.7-2 and leave for 30-50 minutes;

b)． According to the material ratio of p-hydroxybenzaldehyde: nitromethane: glacial acetic acid = 1:1-3:9-18, add p-hydroxybenzaldehyde and nitromethane to the solution of step a), and then add p-nitrobenzene Formaldehyde mass 10-60% ammonium acetate, heated to 60-110°C and reacted for 2-8 hours;

c)． According to the material ratio of p-hydroxybenzaldehyde to toluene is 1:4-8, add toluene to the reaction solution, while distilling away the azeotrope of water and toluene, continue the reaction for 30-40 minutes, and after cooling, obtain 4- Hydroxy-nitrostyrene reaction solution.

Main reference materials

[1] CN201810629054.2 A new preparation method of 4-hydroxy-β-nitrostyrene

[2] CN201310431907.9 Synthesis method of p-hydroxy-β-nitrostyrene