Phosphotungstic Acid Catalyzed Mixed Alcohol

Esters are widely used as solvents, perfumes and preservatives. They are very important in food, industry, daily chemical industry and pharmaceutical production. Esterification is one of the most important reactions in organic synthesis. It is usually the reaction of organic acids and alcohols to produce esters and water. Traditional schemes have serious environmental pollution.

At present, the application of phosphotungstic acid as a catalyst in the esterification of C4-C5 alcohol with acetic acid only involves a single alcohol and acid reaction, while the simultaneous reaction of mixed alcohols with acid has not been reported. Therefore, some scholars have proved that phosphotungstic acid as a catalyst can make C4-C5 mixed alcohols react well with a single acid at the same time. The operation steps of this reaction are as follows:

The product is obtained by adding n-butanol and sec-butanol of 0.11 mol, acetic acid of 0.20 mol, cyclohexane of 8 mL, phosphotungstic acid of 0.504 g into three flasks with reflux water separator, heating at 95℃ for 3 hours under stirring and refluxing. The reaction ends, stirring stops, heating stops and cooling to room temperature. The chemical formula of phosphotungstic acid is H₃PO₄·12WO₃·H₂O.

The products were tested by gas chromatography with external standard method.

Test conditions: gasification chamber temperature 230 ℃, detector: FID, detector temperature 230 ℃, carrier gas: nitrogen (99.9%), shunt ratio: 30:1, N2000 chromatographic workstation processing data.

Separation conditions: keep for 1 minute at 40 ℃, rise to 170 ℃ at 10 ℃/min, and keep for 1 minute at 170 ℃.

According to the gas chromatogram obtained by the test, the selectivity and the yield were calculated. When the phosphotungstic acid was used as the catalyst, n-pentanol and isoamyl alcohol could fully react with acetic acid at the same time, and the selectivity of both was high. The yields of n-amyl acetate and isoamyl acetate were equal, indicating that the mixing reaction did not affect the yield of both.

It can be proved by the above experiments that the phosphotungstic acid as a catalyst enables the C4-C5 mixed alcohol to react well with a single acid at the same time. The mixed alcohol of any two of n-butanol, sec-butanol and tert-butanol can be fully reacted with acetic acid at the same time, and the yield of the product is quite different. This method facilitates product separation and purification in industrial production; n-pentanol and different Pentanol is also capable of fully reacting with acetic acid at the same time, and both have high selectivity and yield, and the mixing reaction has almost no effect on the yield. And phosphotungstic acid has good selectivity and high catalytic activity, mild reaction conditions and environmental friendliness. The catalyst itself can be effectively prevented from corroding the reaction equipment, and the catalyst itself is slightly polluted by the environment, which effectively promotes the conversion of the production of the carboxylic acid ester to the green synthesis, and greatly reduces the social cost of the chemical production.

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