Background and overview[1-2]
P-Aminobenzyl alcohol is an aromatic amine compound. Aromatic amine compounds are extremely important organic raw materials and are widely used in dyes, medicines, agricultural chemicals, additives, surfactants, textile auxiliaries, chelating agents and Preparation of polymers, flame retardants, etc. Para-aminobenzyl alcohol can be obtained by reducing 4-aldehyde nitrobenzene.
Preparation[1-2]
Report 1,
Half-sandwich ruthenium complex 2a catalyzes the reduction of 4-aldehyde nitrobenzene to obtain p-aminobenzyl alcohol. The method is as follows:
Synthesis of half-sandwich ruthenium and 2,6-dithione-substituted pyridine coordination compound 2a: At 25°C, weigh [(CymeneRuCl2)2] (0.05mmol), 2,6-dimethylimidazolethione-substituted pyridine (0.1mmol) in the Schlenk reaction tube, then add 5ml DCM, and stir under nitrogen protection for 16 hours. After the reaction, filter the solution, remove the solvent with a rotary evaporator, add 2 mL CH3OH to dissolve the solid, and then add a saturated aqueous solution of KPF6 (containing 0.25 mmol KPF6), a solid was immediately produced, which was washed with a small amount of water and diethyl ether to obtain 58 mg of a yellow-brown solid with a yield of 71%.
In an air atmosphere, put a polytetrafluoroethylene magneton in the reaction tube, add 7.5×10-4mmol of the half-sandwich ruthenium coordination compound 2a, and add 0.3mmol 4- Aldehyde nitrobenzene, 0.0375ml CH3CN and 1.5ml water, 1.3mmol NH3BH3, 0.021 rubber additive mmol CTAB , stir at 80°C for 10 hours under vacuum conditions. After the reaction, the reaction solution was transferred to a separatory funnel, and ethyl acetate was added for extraction three times (1 ml each time). After gas chromatography-mass spectrometry (GC-MS) analysis, p-aminobenzyl alcohol was obtained (yield 99.2%). ).
Report 2,
Prepare aniline in one pot using imported carbon black at 80°C and a molar ratio of hydroxylamine hydrochloride/concentrated sulfuric acid/p-hydroxymethylacetophenone of 1.0:4:1. Weigh p-hydroxymethylacetophenone (2.68g) into a 100mL three-necked bottle, and add concentrated sulfuric acid (H2SO4 98%, 4.30mL, 0.08mol ), add hydroxylamine hydrochloride (1.40g) under stirring conditions, raise the temperature to 80°C and react for 3 hours. After cooling, slowly add hydrochloric acid (6mol/L, 10 mL), continue stirring and raise the temperature to 100°C, cooled after 2 hours of reaction, crystals precipitated, filtered, washed with hydrochloric acid, washed with ethanol, and vacuum dried in a glass drying oven. The yield was 60%.
References
[1] [Chinese invention] CN201911141553.8 Half-sandwich ruthenium thione complex and its preparation method, hydrolysis method of ammonia borane and reduction method of nitrobenzene compounds
[2] [China invention, China invention authorization] CN201810045739.2 A one-pot method for preparing aromatic amines from aromatic ketones
