JPS6236508B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention is based on HF, HF- _H2O or HF- _BF3-
This invention relates to a method for purifying crude fatty acids obtained by separating a catalyst from a reaction product obtained by reacting an aliphatic alcohol with carbon monoxide in the presence of an H ₂ O catalyst. Olefins such as isobutylene and diisobutylene, or alcohols such as isobutyl alcohol, n-butyl alcohol, and 2-ethylhexanol are reacted with carbon monoxide in the presence of a strong acid catalyst such as sulfuric acid, HF, and BF ₃ to produce the olefin. The reaction that produces fatty acids with one more carbon than alcohol is widely known as the Kotsuho reaction. Among these, HF, HF−H ₂ O or
After separating the catalyst from the reaction product obtained using HF-BF ₃ -H ₂ O, the fatty acid obtained by the reaction is purified by distillation using a conventional method. Colored yellow and colored, about 2
Hazen hue exceeds 300 in a week. It is not clear what kind of substances cause this coloration, but there are side reaction products that are particularly likely to be produced when the Kotsuho reaction is carried out using the above catalysts, such as fluorine-containing compounds or compounds with multiple unsaturations in the molecule. It is thought that these are derived from compounds with bonds, but it goes without saying that in any case, these things significantly reduce the value of the product. The inventor has developed HF, HF- _H2O system or HF- _BF3
-As a result of various studies on the purification of crude fatty acids obtained when alcohol and carbon monoxide are reacted using a H ₂ O catalyst, it was found that by bringing the crude fatty acids into contact with water and then purifying them by distillation, It has been found that the coloring of fatty acids after distillation becomes almost observable over time. That is, the present invention relates to HF, HF-H ₂ O-based or HF-
One carbon number from the alcohol obtained by separating the catalyst from the reaction product obtained by reacting an aliphatic alcohol having three or more carbon atoms with carbon monoxide in the presence of a BF ₃ -H ₂ O catalyst. When distilling a large amount of crude fatty acids to obtain purified fatty acids, this method involves first bringing the crude fatty acids into contact with water and then distilling them. The raw material alcohols used in the present invention include aliphatic alcohols having 3 or more carbon atoms that can be used in the Kotsho reaction, such as propyl alcohols, butyl alcohols, and octyl alcohols, as well as derivatives of these alcohols. The alcohol alone or together with a solvent is reacted with HF, HF- in a reaction system saturated with carbon monoxide gas.
After reacting using a H ₂ O-based or HF-BF ₃ -H ₂ O-based catalyst, the reaction product is hydrolyzed or thermally decomposed to form an organic layer containing a fatty acid and used for the reaction. It is separated into a catalyst layer containing a catalyst. At this time, in order to completely recover the fatty acids produced by the reaction from the catalyst layer after hydrolysis, the fatty acids are extracted using an extractant such as pentane, hexane, or heptane, and are also used as a heating medium in the pyrolysis method. Obtained as a solution in pentane, hexane, benzene, etc. The crude fatty acid obtained by separating the catalyst from the reaction product in this way contains, in addition to the above-mentioned solvents, low-boiling substances by-produced during the reaction, and high-boiling substances with a boiling point 50°C or more higher than the boiling point of the target fatty acid. A thing exists. In the present invention, some or all of these contaminants are removed, or the crude fatty acid is brought into contact with water without being removed, and then fractionated. In particular, the concentration of the solvent remaining in the crude fatty acid is It is preferable to remove it to 30% by weight or less, preferably 10% by weight or less, and then contact it with water. The water to be brought into contact with the crude fatty acid may be supplied to the contact treatment device in either vapor or liquid form. Further, even if the water brought into contact with the crude fatty acid contains inorganic salts such as sodium chloride, potassium chloride, and sodium fluoride, this does not affect the effect of removing coloring substances. These inorganic salts react with a small amount of catalyst entrained in the crude fatty acid, and bring about secondary effects in the present invention, such as reducing the amount of fatty acid dissolved in the aqueous layer. There are no particular restrictions on the treatment temperature and pressure when contacting with water, but
The temperature is preferably in the range of 0 to 100° C. in order to carry out the treatment under atmospheric pressure, which is suitable as an industrial operating condition. The contact time is from a few seconds to 100 hours, preferably from 1 minute to 2 hours. The ratio of crude fatty acid to water is 1 crude fatty acid.
0.01 parts by weight or more, preferably 0.1 parts by weight
Parts by weight or more. Any conventional method for contacting the crude fatty acid with water can be used, such as a stirring mixing tank or a countercurrent continuous contact device. By distilling the organic layer of the crude fatty acid after contact with water using a known method, it is possible to easily obtain a crude fatty acid in which almost no coloration is observed over time. Example 1 A stainless steel reactor with an internal volume of 3 and equipped with an electromagnetic stirrer was filled with 2000 g of HF and 80 g of water, and after the temperature was set to 60°C, the total pressure at which carbon monoxide was supplied to the reactor was reduced to 7.5.
Kg/cm ² G. This is isobutyl alcohol
370 g of pivalic acid was supplied, and stirring was continued while maintaining the total pressure at 7.5 Kg/cm ² G until the absorption of carbon monoxide stopped, and the synthesis reaction of pivalic acid was carried out. After the reaction was completed, the reaction mixture was hydrolyzed with a total of 2500 g of ice to separate the organic layer and the aqueous layer. After separating the organic layer, the aqueous layer was extracted three times using 400 ml of n-heptane each time to extract pivalic acid from the aqueous layer. The extract was combined with the first organic layer to obtain a total of 1340 g of a pivalic acid solution in n-heptane. The yield of pivalic acid thus obtained was 92 mol% (gas chromatography).
(based on analysis). After the above n-heptane solution was thoroughly washed with 10% brine, most of the n-heptane was distilled off at normal pressure. The content of n-heptane in crude pivalic acid obtained as pot residue is 2.8
It was in weight%. This crude pivalic acid was divided into three equal parts, and 1 part by weight was
It was shaken vigorously with 0.3 parts by weight of water for 3 minutes to ensure sufficient contact with the water. The oil layer was then distilled under reduced pressure using a packed column (12 theoretical plates) packed with Dickson packing to obtain 138 g of pivalic acid with a purity of 99.7% (Fraction A). Next, the remaining 2 parts by weight of crude pivalic acid was distilled under reduced pressure using the same packed column as above to improve the purity.
283 g of 99.5% pivalic acid was obtained (Fraction B). Since this fraction was colored slightly pale yellow immediately after distillation, 100 g of fraction B was redistilled to obtain 58 g of almost colorless pivalic acid (fraction C). Furthermore, when 150 g of fraction B was washed with 0.1 part by volume of water, the oil layer became almost colorless. This oil layer was distilled under reduced pressure using a packed column (approximately 3 theoretical plates) to obtain 132 g of purified pivalic acid (Fraction D). Table 1 shows the change in hue of each of these fractions over time. These results show that the water washing treatment of crude pivalic acid is extremely effective.

[Table] Example 2 Pivalic acid was synthesized under the same conditions as in Example 1. The yield of pivalic acid was 91 mol%. The reaction mixture is continuously fed to a packed column in which hexane is refluxed, thermally decomposed, and organic components and catalyst are separated.
A hexane solution containing 51% by weight of pivalic acid was recovered from the bottom of the column with a recovery rate of 51% by weight. After shaking this solution vigorously with 10% saline solution,
The oil layer was distilled under atmospheric pressure to obtain 485 g of colored crude pivalic acid (hexane content: 1.2% by weight). This was treated in the same manner as in Example 1 to obtain fractions A, B,
C and D were obtained, and the change in hue of each fraction over time was observed. The results are shown in Table 2.

[Table] Example 3 1000g of HF and water were added to the reactor used in Example 1.
After filling the reactor with 30 g and raising the reactor temperature to 30° C., pivalic acid was synthesized by supplying 370 g of -t-butyl alcohol while maintaining the reaction system at 5 kg/cm ² G with carbon monoxide. After completion of the reaction, the yield of pivalic acid based on t-butyl alcohol was 93 mol%. The reaction mixture was fed to the hexane reflux column used in Example 2 to separate the reaction product and catalyst, and 964 g of a 49.5% by weight pivalic acid solution was obtained from the bottom of the column. This was treated in exactly the same manner as in Example 2 except that 10% by weight saline was used as the washing water to obtain fractions A, B, C, and D. Table 3 shows the change over time in the degree of coloration of each fraction.

[Table] Example 4 1000g of HF and BF ₃ were added to the reactor used in Example 1.
The reactor was charged with 840 g of isobutyl alcohol and 373 g of water, the temperature was set at 60° C., and the total pressure was kept at 7 Kg/cm ² G by pressurizing with carbon monoxide, and 740 g of isobutyl alcohol was fed into the reactor to synthesize pivalic acid. After the reaction was completed, the entire reaction mixture was hydrolyzed using 1500 g of ice in the same manner as in Example 1, and the reaction product was extracted from the aqueous layer three times with 300 ml of n-heptane each. The yield of pivalic acid based on isobutyl alcohol was 93 mol%. The n-heptane solution of pivalic acid obtained above was further washed with an equal amount of 10% by weight brine, and the solvent was distilled off under reduced pressure to obtain 1130 g of crude pivalic acid (4.2% by weight n-heptane). Crude pivalic acid was treated in the same manner as in Example 1 to obtain fractions A, B, C, and D, and changes over time in the degree of coloration of each fraction were observed.

[Table] Example 5 The reactor used in Example 1 was filled with 2000 g of HF, and the temperature was set at 50°C. Neononenic acid was synthesized by supplying 650 g of 2-ethylhexanol to the reactor while pressurizing the reactor with carbon monoxide and maintaining the pressure at 20 kg/cm ² G. After the reaction, the entire reaction mixture was fed to the hexane reflux column used in Example 2 to separate the reaction product and catalyst, and a 32.5% by weight neononenoic acid solution was poured from the bottom of the column.
Obtained 2409g. The yield of neononenoic acid based on 2-ethylhexanol was 89 mol%. This was treated in the same manner as in Example 1 to obtain fractions A, B,
C and D were obtained, and changes over time in the degree of coloration of each fraction were observed. The boiling point of the neononenoic acid fraction is 132 to 134.
℃/15mmHg, the purity by gas chromatography was 98.3% by weight. As is clear from Table 5, in the case of neononenoic acid as well, it was recognized that coloring substances could be removed by washing with water.

【table】

Claims (1)

[Claims] 1 Catalyst from the reaction product obtained by reacting an aliphatic alcohol having 3 or more carbon atoms with carbon monoxide in the presence of an HF, HF-H ₂ O or HF-BF ₃ -H ₂ O catalyst. 1. A method for purifying fatty acids, which is characterized in that when distilling a crude fatty acid having one more carbon atoms than the alcohol obtained by separating to obtain a purified fatty acid, the crude fatty acid is brought into contact with water in advance and then distilled.