Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Patent
1995-06-05
1998-01-20
Geist, Gary
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
502343, 568861, C07C 29149
Patent
active
057103496
DESCRIPTION:
BRIEF SUMMARY
This is the U.S. National Stage Application of PCT/JP94/01664 filed Oct. 5, 1994 now WO95/10497 published Apr. 20, 1995.
TECHNICAL FIELD
The present invention relates to a process for producing diol compounds, for example, 1,6-hexanediol, 1,5-pentanediol and 1,4-butanediol by esterifying a carboxylic acid mixture collected from a reaction product mixture liquid of a liquid phase oxidation of cyclohexane with air, and then hydrogenate-decomposing the resultant esterification product. The diol compounds are useful for polyurethane elastomers, additives for synthetic resins, and intermediates of medicines and agricultural chemicals.
BACKGROUND ART
Cyclohexanol and cyclohexanone, useful as materials for the synthesis of .epsilon.-caprolactam, are industrially produced by a liquid phase oxidation of cyclohexane with air. Also, diols, for example, 1,6-hexanediol, are produced by esterifying a carboxylic acid mixture obtained as a by-product of the above-mentioned oxidation reaction with an alcohol, and then hydrogenate-decomposing the resultant esterification product with hydrogen.
In the oxidation reaction of cyclohexane, as a by-product, various carboxylic acids including monobasic acids, for example, caproic acid, valeric acid, butyric acid, propionic acid and acetic acid, and dibasic acids, for example, adipic acid, glutaric acid and succinic acids, are produced. Also, the oxidation product includes various oxyacids, for example, .epsilon.-oxycaproic acid and its cyclization product, namely .epsilon.-caprolactone. It is known from, for example, "Catalyst", 33, 5, 341 (1991), that the carboxylic acid mixture can be correct-recovered from the oxidation product mixture liquid by extracting with water or rinsing with an aqueous solution of sodium hydroxide or sodium carbonate.
In a process for producing diols, for example 1,6-hexanediol, as disclosed in Japanese Examined Patent Publication (Kokoku) No. 49-27164, a carboxylic acid mixture extracted with water as mentioned above is esterified with an alcohol, particularly a diol, for example, 1,6-hexanediol, and then the resultant esterification product is hydrogenate-decomposed with hydrogen under atmospheric or higher pressure at a reaction temperature of 200.degree. to 350.degree. C., in the presence of a hydrogenation catalyst consisting of a copper-chromium-containing catalyst, and the diols are separated from the reaction product mixture liquid.
In another process as disclosed in Japanese Examined Patent Publication (Kokoku) No. 53-33567, the sodium salt of the carboxylic acid obtained by the above-mentioned alkali-rinsing is neutralized, a carboxylic acid mixture comprising, as principal components, adipic acid and oxycaproic acid is extracted with an organic solvent, for example, methylisobutylketone, the resultant extract is esterified with a diol compound, for example, 1,6-hexanediol, and then the esterification product is hydrogenate-decomposed with hydrogen under a pressure of 200 to 300 kg/cm.sup.2 at a reaction temperature of 240.degree. to 290.degree. C., to produce diol compounds.
In these processes in which the carboxylic acid mixture separated from the reaction product mixture liquid of the liquid phase oxidation of cyclohexane with air is esterified, and the resultant esterification product is hydrogenate-decomposed with hydrogen to produce diol compounds, for example, 1,6-hexanediol, alcohols including, as principal components, diols which are the reaction product, are used as an esterifying agent. This is due to the fact that the esterification of the carboxylic acid mixture without using a catalyst needs to be effected at a high reaction temperature of 200.degree. C. or more, and thus when a monohydric alcohol, for example, methyl alcohol or ethyl alcohol is used, the reaction must be carried out under a high pressure, and the high temperature high pressure process requires expensive reaction equipment, is significantly dangerous and thus is not industrially preferable. Also, to effect the esterification at a reduced temperature, it has
REFERENCES:
patent: 2524892 (1950-08-01), Horlenko et al.
Furusaki Shinichi
Matsuda Masaoki
Miyamoto Yasunori
Shiomi Yasushi
Geist Gary
Padmanabhan Sreeni
Ube Industries Ltd.
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