Process for preparing 1,3-alkanediols from 3-hydroxyesters

Details Process for preparing 1,3-alkanediols from 3-hydroxyesters Process for preparing 1,3-alkanediols from 3-hydroxyesters

2001-11-29

2003-09-09

Richter, Johann (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Oxygen containing

C568S861000

Reexamination Certificate

active

06617477

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process for preparing 1,3-alkanediols from 3-hydroxyesters. More specifically, the present invention relates to a hydrogenation catalyst for preparation of 1,3-alkanediols from 3-hydroxyesters in a high yield as well as a process for preparing 1,3-alkanediols by hydrogenating 3-hydroxyesters in the presence of the catalyst.
2. Description of the Prior art
1,3-alkanediols have been widely used as coating materials or intermediates for various organic syntheses as well as raw materials for production of polyesters. At present, several processes are known for preparing 1,3-alkanediols. For example, a process for preparing 1,3-alkanediols by hydroformylating epoxides into 3-hydroxyaldehyde derivatives and then hydrogenating the 3-hydroxyaldehyde derivatives has been used (See U.S. Pat. Nos. 5,770,776; 5,723,389; 5,731,478; and 5,777,182). Further, a process for preparing 1,3-alkanediols by hydrating acrolein into 3-hydroxypropanal and then hydrogenating the resulting 3-hydroxypropanal has been also used (see European Patent No. 577,972; U.S. Pat. No. 5,093,537). In addition to the above processes, another method has been reported to provide 1,3-alkanediols through a certain biological reaction, wherein glycerol is used as a starting material (see European Patent No. 361,082; German Patent No. 3,734,764).
On the other hand, Shell Co. has commercially produced 1,3-propanediol through hydrogenation of 3-hydroxypropanal, which is prepared by hydroformylation of ethylene oxides. However, this process has disadvantages in that the unstable 3-hydroxypropanal is likely to oligomerize itself and many other side products including acetal are produced. Thus, hydrogenation into 1,3-propanediol cannot be properly completed, and the quality of the final product is lowered.
Even though an alternative process was suggested, wherein 1,3-alkanediols are prepared by carboesterifying epoxides with carbon monoxides and alcohols to produce 3-hydroxyesters, and then hydrogenating the ester groups of the 3-hydroxyesters, it has not been put to practical use in the industrial field. This is because the reaction pathway thereof is very unselective for producing 1,3-alkanediols from 3-hydroxyesters when a conventional hydrogenation catalyst, such as copper-chromium oxide, copper-zinc oxide or Raney nickel, is used.
Meanwhile, many heterogeneous hydrogenation catalysts for gas-phase or liquid-phase processes have been proposed and actively used in the industrial field, which convert esters, carbonyl compounds, or C
4
or more dicarboxylic esters such as alkylmalate and cyclohexane dicarboxylic ester into their corresponding monoalcohols, 1,4-butanediol, and 1,4-cyclohexanedimethanol, etc. Such ester-hydrogenating catalysts can be found in, for example, U.S. Pat. No. 5,406,004. There are disclosed various Cu-containing catalysts, for example, including Cu—Al
2
O
3
catalysts, reduced CuO/ZnO-based catalysts (Cu:Zn=0.4:1~2:1), and reduced Cu-chromite-based catalysts (Cu:Cr=0.1:1~4:1). In addition, there are also disclosed several catalysts modified with Ba, Mn, rare-earth metals (for example, La, Sm, Th, Ce, Y, etc.), Mg or Ca for 0.1~15 wt % of the CuO/ZnO or Cu-chromite catalysts. Moreover, some catalysts further comprising, if necessary, carriers such as alumina or zirconia are also well known in the art. All of the above catalysts are commercially available. Further, there are also known Pd—Zn catalysts (see U.S. Pat. No. 5,185,476), Cu—TiO
2
catalysts (see U.S. Pat. No. 4,929,777), Re-Cu-Zn catalysts (see European Patent No. 373,946), Zn—Ru catalysts (see U.S. Pat. No. 4,443,649), and Pd, Pt or Ru-containing catalysts.
Even though a number of Cu-containing catalysts and noble metal-containing catalysts have been studied and developed for use in preparing alcohols from their corresponding carbonyl group-containing compounds, particularly from esters, there have been proposed few catalytic processes useful for preparation of 1,3-alkanediols from 3-hydroxyesters having a hydroxyl group in the specific &bgr;-position. WO 00/18712 discloses use of a Cu/ZnO-based catalyst in preparation of 1,3-propanediol from methyl 3-hydroxypropionate, but it was found to have no meaningful catalytic activity in consideration of industrial applicability.
U.S. Pat. No. 4,973,769 and WO 99/38613 describe Cu—Al
2
O
3
-based catalysts and Ru—Re-based catalysts, respectively, as catalysts to be used for preparing 1,2,4-butanetriol from malic acid or malic ester having a hydroxyl group in the &bgr;-position. In these references, however, relatively high pressure ranging from 100 to 300 atm is required as an essential reaction condition, so that these prior catalysts are unsuitable to be applied to a process for preparing the desired compounds of the present invention.
On the other hand, WO 00/18712 describes a method for hydrogenating methyl 3-hydroxypropionate to 1,3-propanediol in the presence of an alcohol solvent such as methanol. Although the alcohol solvent is expected to be able to suppress generation of lactones from 3-hydroxyesters and degradation of their ester groups, it is not helpful to maintain high selectivity at a high conversion rate and to ensure long-term reaction stability of the catalyst, since an alcohol having a low boiling point exists in the gas phase under the flow of H
2
gas in a fixed bed reactor. In fact, a significant decrease in the selectivity at a high conversion rate can be easily found in the Examples of the cited reference. Moreover, the boiling points and the other chemical properties of the reactants, i.e., hydroxyesters, and the products, i.e., 1,3-alkanediols, are so similar that isolation and purification of the product from the reactant are often difficult, which leads to problems in a practical process.
As compared with the hydrogenation of conventional esters, the hydrogenation process for 3-hydroxyesters substituted with a hydroxyl group at their &bgr;-position has numerous problems. The reactants are chemically and thermally so unstable that dehydration of the hydroxyl groups at their &bgr;-position can readily occur, and the resulting unsaturated esters are easily reduced to generate undesirable side products such as saturated esters or corresponding mono-alcohols wherein ester groups have been reduced. Additionally, &bgr;-lactone compounds generated from an intramolecular reaction of 3-hydroxyesters are thermally so unstable as to be degraded spontaneously or to form lactone polymers, and they are converted into additional side products including various esters and lactone compounds through intermolecular reactions with the other reactants or through condensation reaction with 1,3-alkanediols which are derived from hydrogenation of 1,3-hydroxyesters. The extent to which these side reactions occur is affected by reaction temperature, so there is a limit in controlling the reaction rate by increasing the reaction temperature.
However, keeping a high pressure in order to provide a moderate activity under a low temperature will also causes trouble in industrial application.
SUMMARY OF THE INVENTION
A feature of the present invention is to provide a novel process for preparing 1,3-alkanediols from 3-hydroxyesters, wherein a novel hydrogenation catalyst exhibiting high catalytic activity as well as high selectivity even under mild reaction conditions is employed.
According to one aspect of the present invention, there is provided a novel process for preparing 1,3-alkanediols from 3-hydroxyesters in a high yield, which comprises the steps of hydrogenating 3-hydroxyesters, for example in an alcohol-containing solvent, in the presence of a novel hydrogenation catalyst. The catalyst is prepared by adding an alkaline precipitator, such as an alkali metal carbonate or sodium hydroxide, to an aqueous solution containing a copper salt to form particles, and then aging the particles following the addition of colloidal silica thereto.
In more particular embodiments, the catalyst further includes

Affiliated with

Also associated with

Rating

Process for preparing 1,3-alkanediols from 3-hydroxyesters does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Process for preparing 1,3-alkanediols from 3-hydroxyesters, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for preparing 1,3-alkanediols from 3-hydroxyesters will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3099976