反应详情

A crude sorbic acid was prepared by decomposing a polyester with hydrochloric acid, which polyester was prepared by a reaction of ketene with crotonaldehyde. A total of 100 g of the crude sorbic acid (moisture content: 20% by weight, tar content: 4% by weight, sorbic acid: 76% by weight) was dissolved at 120° C. in 320 g of a commercially available lubricating oil having a boiling point ranging from 200° C. to 250° C. The solution was heated and evaporated at a pressure of 30 mmHg till a bottom temperature reached 170° C. The vapor was purified with a packed mist separator, was then cooled and condensed with a contact condenser in which water was circulated and was collected as a slurry mixture of water, lubricating oil, and sorbic acid. The slurry mixture was immediately filtered to yield 102 g of a purified sorbic acid wet cake (moisture content: 20% by weight, ethanol: 10% by weight, sorbic acid: 70% by weight). A total of 33 g of water was added to 50 g of the purified sorbic acid wet cake, and the mixture was neutralized with a 49% by weight potassium hydroxide (KOH) aqueous solution. The neutralized solution was allowed to stand to separate and remove the lubricating oil content. To the resulting solution, 1 g of activated carbon (SHIRASAGI A, a product of Takeda Chemical Industries, Ltd.) was added and the mixture was stirred for 30 minutes. The treated mixture was filtered, and the color valency of the filtrate was determined as a light transmittance at a wavelength of 430 nm with a spectrophotometer and was found to be 98.0%. The aqueous solution was dried under reduced pressure (30 mmHg, 55° C.) to yield 46 g of potassium sorbate. The potassium sorbate had a color valency of 98.0% as determined by dissolving 2 g of the potassium sorbate in water to make 10 ml, and determining the light transmittance of the aqueous solution at 430 nm with a spectrophotometer. The potassium sorbate was air-sealed and was left for 6 months, and was then found to have a color valency of 94.5%.

1. customto separate
2. customremove the lubricating oil content
3. addition) was added
4. filtrationThe treated mixture was filtered
5. customThe aqueous solution was dried under reduced pressure (30 mmHg, 55° C.)