Binuclear Morpholine Phosphotungstate Catalyst

Benzaldehyde is a common intermediate for dyestuff production, and also an important raw material for preparing fine chemicals such as medicine, perfume and coatings. Traditionally, the main production methods of benzaldehyde are oxidation of toluene or chlorination hydrolysis of toluene. However, they have many problems, such as complex process, halogen residue and low selectivity.

From the point of view of economy and environmental friendliness, selective catalytic oxidation of benzyl alcohol to benzaldehyde has great prospects and has been extensively studied. In recent years, heteropoly acid (phosphotungstic acid or silicotungstic acid) has been widely used in organic synthesis as a new catalytic material with excellent performance and environmental friendliness. Although Heteropoly salts can obtain better catalytic effect, there are some problems such as catalyst recovery.

Binuclear morpholine phosphotungstate catalyst is a typical case in which organic cations of ionic liquids are combined with heteropoly acid anions. The preparation method includes the following steps:

1,4-dibromobutane was dissolved in acetone. Morphine was added through a constant pressure dropping funnel. The molar ratio of 1,4-dibromobutane to morpholine was 1:2, the molar ratio of 1,4-dibromobutane to morpholine was 1:1-2, and the reaction time was 5 h in ice bath. After the reaction, the unreacted raw materials were separated by centrifugation, and the remaining solids were washed with 50 mL acetone three times to obtain white solids. Phosphotungstic acid aqueous solution was prepared by adding 50 mL deionized water to a certain amount of phosphotungstic acid. Then, the water solution of phosphotungstic acid was dripped into three flasks under the condition of ice bath. The reaction lasted for a certain period of time, and then the water was removed by centrifugal separation. The solid was dried to constant weight in the oven. Finally, the grey solid was obtained as the final product.

Using binuclear morpholine phosphotungstate as catalyst, the binuclear morpholine phosphotungstate, hydrogen peroxide and benzyl alcohol are mixed, reacted for a period of time under stirring conditions, centrifuged and separated, and the solid catalyst is recovered for use. The liquid is poured into the separating funnel for static stratification, and the separated lower oil phase is benzaldehyde.

The advantages of binuclear morpholine phosphotungstate catalyst lie in its high activity, low dosage, mild reaction conditions, short reaction time, low cost of post-treatment, pollution-free, non-corrosive equipment, environment-friendly and highly competitive clean process route.

• < Prev
• Next >