Preparation method of 4-nitrobenzene propenol_Industrial additives

Background and overview^[1]

4-Nitrophenylpropenol can be used as an intermediate for pharmaceutical synthesis, such as the preparation of α,β-unsaturated aldehydes and ketones. Allyl alcohol compounds, the selective reduction products of α,β-unsaturated aldehydes and ketones, are important fine chemical raw materials and are widely used in the fields of medicine, spices, food additives, and the synthesis of advanced materials. At present, the selective reduction of α,β-unsaturated aldehydes and ketones in industry usually requires hydrogen at a certain temperature and pressure for selective hydrogenation, which poses great safety issues. In recent years, catalytic transfer hydrogenation that utilizes non-hydrogen gas as a hydrogen source, is safe and easy to operate, has attracted increasing attention.

Preparation^[1]

The preparation of 4-nitrobenzene propenol is as follows:

Method 1: 4-nitrobenzaldehyde (0.05mmol), pyridine (0.1mmol) and Au99(SPh)42 nanoclusters (~1mg) or Au99(SPh)42/oxide (100mg, 1wt% loading ) was added to the reactor (ParrInstrumentCompany, 4700 series, 22mL capacity) under H2. The reaction mixture was maintained at 80°C. After the reaction, the mixture was extracted with ethyl acetate. After removal of the solvent, crude product 4-nitrophenylpropenol was obtained.

Method 2: To 4-nitrocinnamic aldehyde (1.0mmol), add 10mL of 2mol/L formic acid/sodium formate aqueous solution (v/v=7:1, latest price of ppvc resin powder H=2.6), and mix the The solution was evacuated/nitrogen replaced three times, and then the round-bottomed flask was frozen in liquid nitrogen under nitrogen protection until the solution was completely frozen into a solid. Then, under vacuum conditions, the round-bottomed flask is slowly heated in warm water to remove dissolved oxygen and other gases in the aqueous solution. After the solid is completely dissolved, nitrogen gas is filled, and “liquid nitrogen freezing and degassing-vacuum-nitrogen protection and thawing” are performed again, repeated three times. Then add the prepared [Cp*Ir(6-OH-py-pz)(OH₂)]SO₄(Ⅳ) catalyst aqueous solution (0.5μmo Cabot carbon black 1), control the reaction temperature to 50°C, and stir the reaction for 15.5 hours under nitrogen protection. After the reaction is completed, extract with CH₂Cl₂ (10mL×3), anhydrous Na₂SO₄ Dry, filter, and rotary evaporate to remove CH₂Cl₂. The yield of purified 4-nitrobenzene propenol was 88%.

Main reference materials

[1] CN201510246826.0 A method for preparing allyl alcohol compounds from α,β-unsaturated aldehydes and ketones