Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
1999-12-16
2001-02-27
O'Sullivan, Peter (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
Reexamination Certificate
active
06194618
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method of producing isobutylene glycol by catalytic reduction of methyl hydroxyisobutyrate. Isobutylene glycol is a useful compound as a raw material for producing polyester resins, polyester plasticizers, lubricating oils, polyester films and polyurethane resins; a solvent; a constitutional component of a developer, a shampoo, a perfume composition and an aqueous composition for unwrinkling fibrous products.
BACKGROUND OF THE INVENTION
There have been various proposals on the method of producing isobutylene glycol. For example, Japanese Patent Application Laid-Open No. 53-12804 discloses a method of producing isobutylene chlorohydrin and isobutylene glycol by reacting isobutene with oxygen-containing gas in an aqueous solution containing halide ion in the presence of a compound or ion of an element selected from the group consisting of tin, tellurium, iridium and titanium. Japanese Patent Application Laid-Open No. 53-65807 discloses a liquid phase oxidation of isobutene in an aqueous solvent in the presence of a catalyst. Japanese Patent Application Laid-Open No. 58-144331 discloses a method of producing a vicinal glycol by irradiating methanol with light in the presence of acetone. Japanese Patent Application Laid-Open No. 59-95226discloses a method of producing diols by hydrogenation of acetone cyanohydrin in a water-containing medium, comprising a fist step of hydrogenating acetone cyanohydrin until one mol of hydrogen is absorbed per one mol of acetone cyanohydrin at −20 to 20° C. under a hydrogen pressure of 10 bar or lower in the presence of a palladium or platinum catalyst and an acid in an amount equivalent to acetone cyanohydrin or more, or in the presence of metallic nickel and an acid in an amount equivalent to acetone cyanohydrin or more, and a second step of hydrogenating acetone cyanohydrin at 30 to 100° C. under a hydrogen pressure of 10 to 150 bar in the presence of metallic nickel.
However, the above methods have problems in putting them into industrial application. For example, in the oxidation of isobutene with oxygen in the presence of hydrogen bromide and tellurium oxide catalyst described in Japanese Patent Application Laid-Open No. 53-12804, isobutylene chlorohydrin is produced 2.6 times as much as isobutylene glycol, thereby resulting in a disadvantageously low yield of isobutylene glycol. In the air oxidation of isobutylene in water solvent in the presence of potassium dichromate described in Japanese Patent Application Laid-Open No. 53-65807,the rate of reaction is low and the yield of isobutylene glycol is unfavorably as low as 38%. In the method taught by Japanese Patent Application Laid-Open No. 58-144331, methanol and acetone in a pyrex reactor are irradiated with light from a high pressure mercury lamp. This method has defects of low rate of reaction and low selectivity to isobutylene glycol due to by-production of ethylene glycol and pinacol. Although the method taught by Japanese Patent Application Laid-Open No. 59-95226 provides a yield of isobutylene glycol relatively as high as 81%, it requires rather complicated reaction operations for industrial use.
SUMMARY OF THE INVENTION
In view of the above problems, an object of the present invention is to provide an industrially advantageous method of producing isobutylene glycol.
As a result of intensive research for solving the above problems, the inventor has found that only the ester group of two functional groups, ester group and hydroxyl group, in methyl hydroxyisobutyrate molecule is selectively hydrogenated by the catalytic reduction using a specific catalyst, thereby to produce isobutylene glycol in a high yield. The selective reduction of the ester group of methyl hydroxyisobutyrate is not known in the art. The present invention has been accomplished based on this finding.
Thus, the present invention provides a method of producing isobutylene glycol comprising a step of catalytically reducing methyl hydroxyisobutyrate in the presence of a catalyst containing at least one of copper component and ruthenium component.
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below in detail.
Methyl hydroxyisobutyrate used in the present invention as the starting material may be produced by several methods. For example, methyl hydroxyisobutyrate may be produced from acetone and methanol as raw materials. Acetone is reacted with hydrogen cyanide to produce acetone cyanohydrin (first step), followed by amidation of acetone cyanohydrin to hydroxyisobutyramide in the present of a manganese catalyst, etc. (second step). Hydroxyisobutyramide is then reacted with methyl formate in the presence of an alkali catalyst, etc. to obtain methyl hydroxyisobutyrate and formamide (third step). The by-produced formamide undergoes pyrolysis in the presence of an iron catalyst, etc. to regenerate hydrogen cyanide (fourth step), which is recycled to the first step. Methyl formate is easily produced by dehydrogenating methanol in the presence of a copper catalyst, etc. (fifth step). Thus, methyl hydroxyisobutyrate is produced at relatively low cost using easily available acetone and methanol as raw materials.
Since methyl hydroxyisobutyrate is converted to methyl methacrylate (MMA) by dehydration in the presence of a zeolite catalyst, etc. (sixth step), MMA has recently come to be industrially produced by a process comprising the first to sixth steps mentioned above. Such a process for manufacturing MMA is characterized by the use of acetone and methanol as main raw materials and the by-production of no ammonium sulfate. The intermediary methyl hydroxyisobutyrate in the MMA manufacturing process may be effectively utilized in the present invention.
The catalytic reduction of methyl hydroxyisobutyrate is exothermic, and usually carried out in a solvent so as to suitably control the temperature rise due to reaction heats or to increase the reaction rate. Although, the solvent usable in the present invention may include an inert solvent selected from aliphatic hydrocarbons such as n-hexane, n-heptane and n-octane; aromatic hydrocarbons such as benzene, toluene, and xylene; alicyclic hydrocarbons such as cyclohexane; and ethers such as 1,4-dioxane and tetrahydrofuran, isobutylene glycol and/or methanol are preferably used as the solvent because the step for recovering the solvent from the liquid reaction mixture and the step for recycling the recovered solvent can be omitted. The solvent is used in an amount so that the concentration of methyl hydroxyisobutyrate in starting mixture is 1 to 50% by weight, preferably 5 to 30% by weight. An amount of the solvent resulting in a concentration lower than the above range decreases the space time yield, while an amount resulting in a concentration higher than the above range makes the temperature control of the reaction zone difficult.
Hydrogen gas of technical grade is sufficient for use in the present invention. For example, a mixed gas of hydrogen and an inert gas such as nitrogen, carbon dioxide and methane is usable. The hydrogen content of the mixed gas is preferably 50 mol % or more. The amount of hydrogen to be used is 2 to 50 mol per one mol of methyl hydroxyisobutyrate. When less than the above range, the amount of methyl hydroxyisobutyrate remaining unreacted is increased, while an amount exceeding the above range is of poor economy because a great amount of hydrogen gas circulates as unreacted.
The catalyst used in the present invention contains at least one of copper component and ruthenium component. A copper base catalyst is preferably a catalyst modified by zinc component and/or chromium component such as a copper-zinc catalyst, a copper-chromium catalyst and a copper-zinc-chromium catalyst. The copper base catalyst may be used directly or may be supported on a carrier such as activated carbon, alumina, silica and diatomaceous earth. The copper base catalyst preferably comprises, assuming that the metal components are all in oxide forms, 20 to 60% by weight of copper oxide, 0
Antonelli Terry Stout & Kraus LLP
Mitsubishi Gas Chemical Company Inc.
O'Sullivan Peter
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