The technical problem to be solved by the present invention is to provide a method for purifying peach aldehyde, which can purify the mixture of fractions produced in the industrial production process of γ-undecalactone, the process method is simple, and the recovery rate of peach aldehyde is high.
For solving the problems of the technologies described above, the purification method of peach aldehyde of the present invention may further comprise the steps:
A. Add the mixture of fractions of peach aldehyde to the hydrolysis reaction kettle, then add sodium hydroxide, and stir for 2 to 15 hours at a temperature of 30 to 120°C; in this step, the peach aldehyde in the mixture of fractions of peach aldehyde The molar ratio to sodium hydroxide is 1:1~6;
B. After the hydrolysis is over, let the reaction system stand still to form two phases, the upper layer of the reaction system is an oil layer, and the lower layer is a water layer; then open the steam pipe in the hydrolysis reaction kettle, blow steam into the kettle, and use the steam to take out the oil layer of the hydrolyzed product ; In this step, the kettle temperature is controlled at 70-170°C;
C. When the distilled water is clarified, stop feeding steam into the kettle, lower the temperature of the kettle to 50°C, add 28% hydrochloric acid solution into the kettle, and control the pH value of the reaction system in the hydrolysis reactor to 2-7. Continue to stir for 2 to 8 hours;
D, leave standstill stratification, separate lower floor water; Upper oil layer adopts tap water to wash 2 times, the oil layer after washing is fractionated, obtains peach aldehyde after the purification.
In the step A, the molar ratio of peach aldehyde to sodium hydroxide in each section of peach aldehyde fraction mixture is 1:1.5. In the step A, the sodium hydroxide is configured into a 20% solution and then added to the hydrolysis reactor. In the step A, the hydrolysis temperature is controlled at 50-80° C.; the hydrolysis reaction time is controlled at 3-6 hours.
In the step B, the temperature of the hydrolysis reactor is controlled at 70-120°C.
In the step C, the pH value in the hydrolysis reactor is controlled at 4-5; the stirring time is 3-5 hours. In the step D, the amount of tap water added is 0.5 to 4 times the weight of the fraction mixture in each stage.
In the step D, the amount of tap water added is 1 to 3 times the weight of the fraction mixture in each stage.
The invention adopts the fraction mixture of each stage in the synthesis process of peach aldehyde and sodium hydroxide as raw materials, and hydrolyzes peach aldehyde, octanoic acid octyl, and intermolecular cyclization products of hydroxy acid into salt. After the hydrolysis is completed, feed steam into the hydrolyzate system to take out the octanol produced by hydrolysis by azeotropic method, and stop feeding steam into the kettle when the distilled water is not turbid and clear. Then use 28% hydrochloric acid to adjust the pH value of the treated hydrolyzate to 4-5, separate the lower water layer; wash the upper oil layer twice with tap water, and fractionate the washed oil layer to obtain peach aldehyde. Adopt the method of the present invention, the recovery rate of peach aldehyde can reach 90%.