TWI535694B - Method for producing 1,3-butanedio - Google Patents

Description

Method for preparing 1,3-butanediol

The present invention relates to a method for preparing 1,3-butanediol

1,3-butanediol is an important industrial product which can be used as a high boiling point solvent, as an antifreeze or as a diol for the preparation of ester compounds, which can be used in combination with polyester. Plasticizer or a coalescing agent. In addition to its use in the industrial category, 1,3-butanediol can also be processed for use as an animal food supplement or for the preparation of cosmetic formulations.

During the synthesis of 1,3-butanediol is generally from C ₂ - Start reactants, such as ethylene, which then-based dimerization reaction by conversion of 1,3-butanediol. However, given the importance of 1,3-butanediol, there is a continuing need for alternative synthetic methods and approaches.

Accordingly, it is an object of the present invention to provide a novel synthetic route to one of 1,3-butanediol. This object can be achieved by the present synthesis method. Accordingly, it is proposed that the synthesis method comprises the steps of: (a) initial synthesis of acetaldehyde from methanol; (b) dimerization of acetaldehyde to 3-hydrocarbylbutyraldehyde; and (c) reduction of 3-hydrocarbylbutanal to 1,3 - Butanediol.

Thus, by the above synthesis process, it can be used immediately by a C ₁ building block, such as methanol, synthetic Initiation of 1,3-butanediol feasible. In particular, the method according to the invention provides one or more of the following advantages in many applications:

- Since acetaldehyde is synthesized by the reaction of two C ₁ building blocks, wherein one of the building blocks represents methanol, the use of ethylene can be eliminated. Based on different sources of raw materials such as natural gas, coal and biological resources, the feedstock methanol can be large and low cost, and can be easily transported as a liquid compound at a normal pressure and room temperature.

- The preparation of acetaldehyde via oxidation according to the general procedure from ethylene is quite complex, requires special materials and is quite ecologically doubtful in terms of waste management.

The individual steps of the above method are described below.

Step (a) acetaldehyde synthesis

The synthesis of acetaldehyde can be carried out in several ways, and therefore, all of them represent preferred embodiments of the invention.

(1) Synthesis of acetic acid by conversion to acetic acid

In a first preferred embodiment, methanol is initially converted to acetic acid by a synthesis gas. Ullmann, Encyclopedia of Industrial Chemistry, 6th Edition, 2003, Wiley-VCH, Vol. 1, pp. 151-165 describes a possible transformation. Here, the carbonization of the methanol is carried out using carbon monoxide in the presence of a rhodium or ruthenium catalyst.

The acetic acid thus obtained can be directly reduced to acetaldehyde. Corresponding and preferred methods are processed, in particular in WO 2010/014146 A2.

Alternatively, acetic acid can also be converted to acetaldehyde via an intermediate stage of ethanol.

Here, the synthesis of ethanol can be carried out according to, for example, Arpe, Industrial Organic Chemistry, Wiley-VCH, 6th edition, page 198. First, acetic acid is converted to methyl acetate by using more methanol, which is Gas phase hydrogenolysis splits into ethanol and methanol, so methanol is obtained, of course, for a new esterification reaction or acetic acid synthesis.

Alternatively, for example, according to WO 2011/056595 or WO 2011/056597, acetic acid can be hydrogenated to ethanol at a raised temperature (125 to 350 ° C) and pressure (10 to 3000 kPa) using hydrogen and a suitable catalyst.

The oxidation of ethanol is preferably carried out by passing the ethanol-air mixture through a silver catalyst at 500 to 650 ° C or by dehydrogenation at 260 to 290 ° C in a promoted copper catalyst. In this regard, it is an exemplary reference to Ullmann Industrial Chemistry Encyclopedia, 6th ed., 2003, Wiley-VCR, Vol. 1, pp. 135-136.

(2) Synthesis using methanol homologation

Alternatively, methanol can be homologized to ethanol using CO/H ₂ . In this regard, iron-cobalt carbonyls have proven to be effective by the use of iodide promoters at pressures of 100 to 250 ° C and 5 to 100 MPa, as described in Ullmann, Encyclopedia of Industrial Chemistry, 6th Edition, 2003, Wiley- VCR, Vol. 12, pages 404-405 and/or U.S. Patent No. 4,320,320.

The ethanol thus obtained can be subsequently converted to acetaldehyde as described above.

(3) Synthesis of direct conversion to acetaldehyde using methanol

The above-described methanol homologation can also be used for the direct synthesis of acetaldehyde using modified reaction conditions, especially a modified CO/H ₂ ratio, temperature and or pressure.

Step (b) becomes dimerization of 3-hydrocarbylbutanal

The acetaldehyde obtained in the step (a) is now dimerized to 3-hydrocarbylbutyraldehyde by a monoalcohol reaction. Here, the above aldol reaction is preferably carried out in an aqueous alkaline solution. In many applications, it has proven to be advantageous to not direct the reaction to completion of the conversion, but to terminate at 50 to 60% conversion, which avoids or reduces the production of by-products. See, in particular, Arpe, Industrial Organic Chemistry, Wiley-VCH, 6th edition, pp. 202-203.

The above process can be easily terminated by adding acid. Unreacted acetaldehyde can be easily removed by evaporation and then returned.

Step (c) is a reduction of 3-hydrocarbylbutanal

The 3-hydrocarbyl butyraldehyde obtained in the step (b) can now be converted to 1,3-butanediol by reduction. In this regard, a number of methods are possible, preferably described, for example, in Kirk-Ohtmer Encyclopedia of Chemical Technology, 3rd edition, New York, 1980, Wiley-Intersciences, Vol. 12 Hydrogenation of Raney nickel is utilized in pages 404-405 and/or in WO 2005/06408.

The above composition and the composition to be used according to the present invention are defined and described in the exemplary embodiments, and are not limited to specific conditions as compared with their size, shape, material selection and technical content, so that the application field has Knowing the selection conditions can be applied without limitation.

The composition of the above-described embodiments, and any combinations of the features of the above-described embodiments are exemplary, and other teachings contained in this document and the reference documents cited therein are also substituted or substituted. Should be considered. It will be appreciated by those skilled in the art that variations, modifications, and other embodiments may be made without departing from the spirit and scope of the invention. Accordingly, the foregoing is illustrative only and not restrictive. The word "comprising", used in the context of the application of the invention, does not exclude other elements or steps. The above indefinite article "一" does not exclude the plural. The mere fact that certain measures are recited in mutually different patent application scopes does not indicate that the combination of such measures cannot be utilized. The invention is defined by the scope of the following claims and their equivalents.

Claims (8)

A process for the preparation of 1,3-butanediol comprising the steps of: (a) initial synthesis of acetaldehyde from methanol; (b) dimerization of acetaldehyde to 3-hydrocarbyl butyraldehyde; and (c) 3-hydrocarbyl butyraldehyde Reduction to 1,3-butanediol. Wherein in step (a), methanol is first converted to acetic acid in a step (a1). The method of claim 1, wherein the acetic acid obtained in the step (a1) is reduced to ethanol (step (a2)) and then oxidized to acetaldehyde (step (a3)). The method of claim 1, wherein the acetic acid obtained in the step (a1) is reduced to acetaldehyde. The method of claim 1, wherein the step (b) is carried out by a monoaldol reaction. The method of claim 4, wherein the aldol reaction occurs by using an aqueous alkaline solution. The method of claim 4, wherein the aldol reaction is terminated at 50 to 60% conversion. The method of claim 1, wherein the step (c) is carried out under hydrogenation. The method of claim 7, wherein Raney nickel is used as a catalyst during hydrogenation.