HK1062012A - Process for preparation of 3, 3-dimethyl-2-oxobutyric acid - Google Patents
Process for preparation of 3, 3-dimethyl-2-oxobutyric acid Download PDFInfo
- Publication number
- HK1062012A HK1062012A HK04104984.6A HK04104984A HK1062012A HK 1062012 A HK1062012 A HK 1062012A HK 04104984 A HK04104984 A HK 04104984A HK 1062012 A HK1062012 A HK 1062012A
- Authority
- HK
- Hong Kong
- Prior art keywords
- dimethyl
- acid
- bismuth
- reaction
- process according
- Prior art date
Links
Description
The present invention relates to a process for producing 3, 3-dimethyl-2-oxobutanoic acid and salts thereof by oxidizing 3, 3-dimethyl-2-hydroxybutyric acid with oxygen and an oxygen-containing gas in an alkaline aqueous medium and in the presence of a palladium catalyst and bismuth or a bismuth compound.
3, 3-dimethyl-2-oxobutanoic acid, especially the aqueous sodium salt solution thereof, for the industrial scale production of agrochemicals, especially the selective herbicide thiacrizine (Sencor)) It is mainly used for the cultivation of soybeans, tomatoes and potatoes (see also us 3,671,523 and us 3,905,801).
EP-A1097917 discloses the liquid phase oxidation of 2-hydroxycarboxylic acids or esters thereof with hypobromous acid. However, the use of hypobromous acid as an oxidizing agent on an industrial scale is not acceptable for ecological and economic reasons.
EP-A0011207 discloses a process for the preparation of 3, 3-dimethyl-2-oxobutanoic acid and/or salts thereof by oxidation of 3, 3-dimethyl-2-hydroxybutyric acid with hypochlorous acid (hypochlorite) in the presence of a ruthenium catalyst in an aqueous alkaline solution. However, in this case, the cost and low environmental compatibility of the oxidizing agent compromises its industrial application.
A similar process disclosed in us patent 5,091,568 overcomes the above-mentioned drawbacks by using oxygen as the oxidant. However, it requires very high amounts of catalyst of up to 5% by weight and high oxygen pressures of 20-40 bar (bar), which makes the process inefficient.
Furthermore, DE-A2915395 discloses that 2-hydroxypropionates can be oxidized with oxygen or air and platinum catalysts at temperatures of from 35 to 70 ℃ with bismuth or lead or their compounds to give from 8 to 90% of sodium 2-oxopropionate. But is not described as being also applicable to the oxidation of 3, 3-dimethyl-2-hydroxybutyric acid or its sodium salt. However, internal studies prove that this method is not at all suitable (see comparative examples).
There is therefore a need to develop a process by which 3, 3-dimethyl-2-oxobutanoic acid or a salt thereof can be prepared in an efficient manner.
It has now been found a process for the preparation of 3, 3-dimethyl-2-oxobutanoic acid or a salt thereof by catalytic oxidation of 3, 3-dimethyl-2-hydroxybutyric acid with a transition metal, characterized in that it is carried out in the presence of:
the oxygen (in) is added to the reaction mixture,
a palladium catalyst, which is a catalyst for the reaction,
bismuth and/or bismuth compounds
Water and
a base.
The parameters and illustrations listed in the general or reference section, as well as in the specific section or sections referenced, may be combined as desired within the scope of the invention.
The 3, 3-dimethyl-2-hydroxybutyric acid in the process of the present invention may be used in any desired mixture, in particular in racemic form, of the D-form, L-form or enantiomer. In addition, 3, 3-dimethyl-2-hydroxybutyric acid may be used at least partially in the form of a salt, in particular an alkali metal salt.
3, 3-dimethyl-2-hydroxybutyric acid may be prepared by known methods, for example by reacting dichloroppinacolone with aqueous bases (see also DE-A2648300). The resulting alkali metal salt solution of 3, 3-dimethyl-2-hydroxybutyric acid may, for example, be used directly in the process of the present invention.
When the process of the invention is carried out, predominantly the salt form of 3, 3-dimethyl-2-oxobutanoic acid is obtained, from which the free acid can be obtained, if desired, by acidification. However, the reaction solution obtained is optionally also used directly for other reactions, for example with thiosymmetrical diaminourea to form 4-amino-6-tert-butyl-3-thio-1, 2, 4-triazin-5 (4H) -one.
The process of the invention is carried out in the presence of a palladium catalyst. Examples of suitable palladium catalysts include metallic palladium, especially palladium black or supported palladium. Examples of suitable supports include activated carbon, graphite, diatomaceous earth, silica gel, spinels, aluminas, calcium carbonate, magnesium oxide, barium sulfate and organic support materials.
The support material used is preferably powdered activated carbon, for example medical carbon or activated carbon prepared from wood, frequently used for deodorizing purposes.
The palladium content of the supported catalyst is not critical and can vary within wide limits. In general, supported catalysts having a palladium content of from 0.1 to 20% by weight, preferably from 0.5 to 15% by weight, are used.
The amount of palladium catalyst used may also vary within a relatively wide range. It is advantageous to expect the rate of oxidation, among other factors. In general, the amount of catalyst is chosen such that the molar ratio of palladium to 3, 3-dimethyl-2-hydroxybutyric acid or its salt used is between 1: 5 and 1: 20,000, preferably between 1: 10 and 1: 10,000, and particularly preferably between 1: 100 and 1: 10,000.
The activity and selectivity of the palladium catalyst in the process according to the invention are significantly increased in the presence of bismuth and/or bismuth compounds thereof, which has a positive effect on the reusability of the palladium catalyst.
The amount of bismuth and/or bismuth compounds thereof used may vary within wide limits. For example, the molar ratio of bismuth or bismuth compound to 3, 3-dimethyl-2-hydroxybutyric acid or its salt used may be, for example, 1.10-6-1·10-1Preferably 5.10-6-1·10-1And particularly preferably 2.10-5-2·10-2. Larger amounts are also possible, but uneconomical.
Bismuth may be used, for example, in elemental form and/or in the form of bismuth compounds, for example as oxides, hydroxides, oxide hydrates or salts of hydrogen acids, for example chlorides, bromides, iodides, sulfides, or as salts of inorganic oxygen acids, for example nitrates, nitrites, phosphites, phosphates, carbonates, perchlorates, or as salts of oxygen acids which are derived from transition metals, or as salts of organic acids or as complexes or as organometallic compounds.
Bismuth and/or bismuth compounds in combination with other metals, semimetals or compounds thereof may also be introduced in the process of the invention.
The bismuth activators used in the present invention may exist in different and mixed valencies. Changes in valency may also occur in this reaction. The bismuth and/or bismuth compound may also be partially or completely converted into other compounds in the reaction medium.
The bismuth and/or bismuth compound can be added to the reaction components as a solid, preferably in the form of a fine powder. However, it is also possible to add bismuth and/or bismuth compounds when preparing the palladium catalyst or to impregnate the palladium catalyst with bismuth and/or bismuth compounds. Bismuth and/or bismuth compounds may also serve as support materials for palladium.
The concentration of the organic compound (3, 3-dimethyl-2-hydroxybutyric acid and reaction products thereof) in the reaction solution is suitably chosen in such a way that both 3, 3-dimethyl-2-hydroxybutyric acid and the 3, 3-dimethyl-2-oxobutyric acid formed are largely or preferably completely dissolved under the reaction conditions. 3, 3-dimethyl-2-hydroxybutyric acid may optionally be added stepwise to the oxidation mixture (optionally together with a base). Suitable concentrations of the organic mixture have proven to be 5 to 30% by weight. For example, lower concentrations are possible, but not cost-effective.
The process of the invention is preferably carried out in the presence of water and a base. The amount of the base is suitably such that a total of 1.1 to 8, preferably 1.2 to 6, molar equivalents of the base per mole of the oxidized 3, 3-dimethyl-2-hydroxybutyric acid is obtained. When 3, 3-dimethyl-2-hydroxybutyric acid is used in the form of an alkali metal salt or an aqueous solution thereof, the amount of base equivalent to the acid has to be taken into account and may already be present in the solution. Larger amounts of base are possible in principle, but uneconomical.
The base used is preferably an alkali metal or alkaline earth metal carbonate or hydroxide, mixtures thereof or corresponding aqueous solutions thereof. Particular preference is given to sodium hydroxide and potassium hydroxide, mixtures thereof or corresponding aqueous solutions.
The reaction is carried out at a pressure of, for example, from 0.1 to 50 bar, preferably from 0.5 to 5 bar, particularly preferably from 0.9 to 1.5 bar and very particularly preferably at atmospheric pressure.
The conversion is suitably carried out at from 20 to 150 ℃.
Desirably, the temperature is selected to be between 60 ℃ and the boiling point of the reaction mixture at the selected reaction pressure.
In a particularly preferred embodiment of the process according to the invention, the lower temperature limit t (lower limit) is selected in accordance with the following formula:
t (lower limit) is 90-n2(° c) where n is the number of equivalents of base used per mole of 3, 3-dimethyl-2-hydroxybutyric acid (DHBA for short).
For example, it may be, for example and preferably, carried out in the range from about 65 ℃ to the boiling point when 5mol of NaOH per mol of DHBA are used, for example and preferably, in the range from about 86 ℃ to the boiling point when 3mol of NaOH per mol of DHBA are used, and for example and preferably, at about 88 ℃ to the boiling point of the reaction mixture when 1.5mol of NaOH per mol of DHBA are used.
Very particular preference is given to operating between 90 ℃ and the boiling point, since such temperatures enable high yields to be obtained in a short time at low and high molar ratios of base to DHBA, and high temperatures at the same time enable good removal of the heat of reaction of the exothermic oxidation process from the viewpoint of the reaction process.
The order in which the palladium catalyst, bismuth and/or bismuth compound, water, base and 3, 3-dimethyl-2-hydroxybutyric acid are mixed may be selected as desired and is not critical. For example, the palladium catalyst and the bismuth and/or bismuth compound may be added to a mixture or solution of water, base and 3, 3-dimethyl-2-hydroxybutyric acid. It is also possible to initially charge the palladium catalyst and the bismuth and/or bismuth compound and to add mixtures and solutions of water, base and 3, 3-dimethyl-2-hydroxybutyric acid. Finally, it is also possible to initially charge the palladium catalyst, a portion of the water-base mixture and the bismuth and/or bismuth compound and subsequently to add 3, 3-dimethyl-2-hydroxybutyric acid, optionally with the remainder of the base or the remainder of the water and base mixture. Bismuth and/or bismuth compounds may also be added to the mixture of the remaining components.
Generally, the process of the present invention is carried out in such a way that oxygen or other oxygen-containing, e.g., air, is brought into contact with a reaction mixture containing water, a base, the palladium catalyst, bismuth and/or bismuth compound and 3, 3-dimethyl-2-hydroxybutyric acid.
The catalyst need not be present as a powder suspended in the reaction mixture, but can also be arranged in the form of particles as a fixed bed, through which the other constituents flow.
The progress of the reaction can be monitored, for example, by measuring the amount of absorbed oxygen. The reaction may be terminated when the amount of oxygen required to obtain the optimum selectivity has been absorbed. In order to obtain high selectivity, it is preferred to terminate the reaction after an oxygen uptake of 0.2 to 0.5mol of oxygen per mole of 3, 3-dimethyl-2-hydroxybutyric acid, particularly preferably an oxygen uptake of 0.4mo1 to 0.5mol of oxygen per mole of 3, 3-dimethyl-2-hydroxybutyric acid. When, in order to obtain good yields, the reaction is preferably terminated after absorption of from 0.4 to 0.6mol of oxygen per mole of 3, 3-dimethyl-2-hydroxybutyric acid, particularly preferably after absorption of from 0.45 to 0.58mol of oxygen per mole of 3, 3-dimethyl-2-hydroxybutyric acid and very particularly preferably after absorption of from 0.50 to 0.56mol of oxygen per mole of 3, 3-dimethyl-2-hydroxybutyric acid. Its value is advantageously favorable, among other factors, for selected reaction and process adjustments, the purity of the desired product, etc., and can be determined in each case by preliminary experiments.
The course of the reaction can also be monitored in other ways, for example by determining the 3, 3-dimethyl-2-hydroxybutyric acid consumed, the 3, 3-dimethyl-2-oxobutyric acid formed and/or the small amount of trimethylacetic acid formed in the subsequent reaction at the end of the reaction due to excessive oxidation.
The treatment in the process of the present invention can be carried out by a conventional method. Typically, the palladium catalyst is removed, for example by filtration, together with the insoluble and adsorbed bismuth and/or bismuth mixture. The resulting solution containing 3, 3-dimethyl-2-oxobutanoic acid, predominantly in its salt form, is optionally used further after partial or complete neutralization of the excess stoichiometric amount of base. However, 3-dimethyl-2-oxobutanoic acid can also be liberated from this solution by acidification with mineral acids, for example hydrochloric acid, sulfuric acid or phosphoric acid, and isolated by known methods, for example by extraction with solvents of low water solubility, such as ethers (for example diethyl ether, isopropyl ether) or ketones (for example methyl isobutyl ketone). The extraction can also be performed simultaneously at different pH levels (see us patent 6,274,766). After distillation of the extract, further purification can be carried out if desired, for example by optionally fractional distillation under reduced pressure. It is also possible to liberate the 3, 3-dimethyl-2-oxobutanoic acid from the alkali metal salt solution with a cation exchanger, isolate the reaction by slight evaporation and, if desired, further purification by fractional distillation.
The 3, 3-dimethyl-2-oxobutanoic acid or salts thereof which can be prepared by the process according to the invention are particularly suitable for preparing agrochemicals, such as thiacridine. Preferably suitable for the preparation of 4-amino-6-tert-butyl-3-thioxo-1, 2, 4-triazin-5 (4H) -one.
The process of the invention is notable for the fact that oxygen (air) can be used as the oxidizing agent at low pressure, the oxidation reaction proceeds in very high yields even at low catalyst concentrations and high conversions also enable high space-time yields.
Examples
Example 1
To a reaction vessel equipped with a stirrer, an internal thermometer and an air inlet tube and capable of being heated with a heating mantle, 1.0g of activated carbon (medical carbon) having a palladium content of 5% by weight, 0.024g of Bi (NO)3)3·5H2O, 100ml of 3N sodium hydroxide solution and 13.2g (0.1mol) of 3, 3-dimethyl-2-hydroxybutyric acid (DHBA).
After the air in the reaction vessel was vented with oxygen, the starting mixture was heated to 95 ℃ and stirred at this temperature until after about 2 hours 0.0535mol of oxygen had been taken up (about 1300ml at room temperature and atmospheric pressure). The oxygen inlet tube and the stirrer were then closed.
After filtering off the catalyst, which can be used repeatedly, the pH of the filtrate is adjusted to 7.5 with 20% hydrochloric acid at room temperature, the amount of filtrate is determined and the 3, 3-dimethyl-2-oxobutanoic acid content in an aliquot is determined by differential pulse polarography (alkaline electrolyte; acetate buffer). The assay is performed relative to a solution of known content of 3, 3-dimethyl-2-oxobutanoic acid, which is used as an internal standard in repeated measurements of the same sample. The yield of 3, 3-dimethyl-2-oxobutanoic acid was determined to be 11.7g (90% of theory).
After acidifying the filtrate to pH 1, extraction with ether and evaporation of the ether were repeated, the presence of about 0.7g (7% of theory) of trimethylacetic acid in addition to 3, 3-dimethyl-2-oxobutanoic acid being detectable in the extraction residue by gas chromatography.
Examples 2 to 5Comparative example
0.1mol (13.2g) of 3, 3-dimethyl-2-hydroxybutyric acid (DHBA) is oxidized to 3, 3-dimethyl-2-oxobutyric acid (DOBA) with oxygen in sodium hydroxide solution at atmospheric pressure using 1g of noble metal/activated carbon catalyst, as described in example 1.
Table 1 shows the kind of the noble metal/carbon catalyst used, the kind and amount of the additive, the amount of the sodium hydroxide solution used, the oxidation temperature, the amount of oxygen absorbed, the time required to absorb these amounts of oxygen, and the DOBA yield as determined by polarography. For comparison, the values for example 1 are also listed in table 1.
TABLE 1
| Examples | 1 | 2 | 3 | 4 | 5 |
| Catalyst and process for preparing same | 5% Pd/activated carbon | 5% Pd/activated carbon | 5% Pd/activated carbon | 1% Pt/activated carbon | 1% Pt/activated carbon |
| Additive agent | Bi(NO3)3 | Pb(NO3)2 | Is free of | Pb(NO3)2 | Pb(NO3)2 |
| [mol/mol DHBA] | 5·10-4 | 1.3·10-3 | — | 5·10-3 | 5·10-3 |
| Sodium hydroxide solution [ mol/mol DHBA] | 3 | 3 | 3 | 4 | 2 |
| Temperature [ deg.C ]] | 95 | 95 | 95 | 95 | 70 |
| O2Absorption of | |||||
| [mol/molDHBA] | 0.535 | 0.090 | 0.090 | 0.005 | 0.015 |
| Time [ hour] | 2 | 8 | 8 | 1 | 1 |
| Stop | Is free of | Almost all of which are | Almost all of which are | Is that | Is that |
| DOBA yield [ theoretical%] | 90 | 5 | 5 | ＜1 | ＜3 |
Examples 6 to 15
0.1mol (13.2g) of 3, 3-dimethyl-2-hydroxybutyric acid (DHBA) are dissolved in 100mL of sodium hydroxide solution (═ 5mol of NaoH per mole of DHBA) at different temperatures in 5.10 g of activated charcoal (medical charcoal) having a palladium content of 5% by weight, as described in example 1-4mol of Bi (NO) as additive3)3Oxidation at atmospheric pressure in the presence of/mol DHBA until about 1.300ml oxygen (about 0.535mol O)2Mol DHBA) has been absorbed. The results concerning the reaction time and the yield of 3, 3-dimethyl-2-oxobutanoic acid (DOBA) determined by polarography are shown in table 2.
TABLE 2
| Examples | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 |
| Temperature [ deg.C ]] | 65 | 70 | 75 | 80 | 85 | 90 | 95 | 97.5 | 100 | 102.5 |
| Time [ h ]] | 42 | 11 | 5.7 | 3.8 | 2.3 | 1.4 | 1.0 | 2.5 | 7.3 | 19 |
| DOBA yield [ theoretical%] | 61 | 73 | 76 | 81 | 77 | 83 | 91 | 92 | 90 | 94 |
Examples 16 to 22
0.1mol (13.2g) of 3, 3-dimethyl-2-hydroxybutyric acid (DHBA) are dissolved in 100ml of sodium hydroxide solutions of different equivalent concentrations, with 1g of activated carbon having a palladium content of 5% by weight (medical charcoal), at 5.10-4mol of Bi (NO) as activator3)3Oxidation in the presence of/mol DHBA at 95 ℃ and atmospheric pressure until about 1.300ml of oxygen (about 0.535mol of O)2Mol DHBA) has been absorbed. The results concerning the reaction time and the yield of 3, 3-dimethyl-2-oxobutanoic acid (DOBA) determined by polarography are shown in Table 3.
Example 16 is a comparative example in which an excess of a stoichiometric amount of base is used.
TABLE 3
| Examples | 16 | 17 | 18 | 19 | 20 | 21 | 22 |
| molDHBA mol of NaOH | 1 | 1.5 | 2 | 3 | 4 | 5 | 7.5 |
| Reaction time [ h] | ＞＞6*) | 5 | 4.4 | 2 | 1.8 | 1 | 0.7 |
| DOBA yield [ theoretical%] | Not determined | 86 | 86 | 90 | 87 | 91 | 82 |
6 hours later, only about 2% (0.01mol of O)2Mol DHBA) and O2The absorption of (a) almost stops.
Claims (18)
1. Process for the preparation of 3, 3-dimethyl-2-oxobutanoic acid by catalytic oxidation of 3, 3-dimethyl-2-hydroxybutyric acid with a transition metal, characterized in that it is carried out in the presence of:
the oxygen (in) is added to the reaction mixture,
a palladium catalyst, which is a catalyst for the reaction,
bismuth and/or bismuth compounds
Water and
a base.
2. A process according to claim 1, wherein the palladium catalyst used is metallic palladium or palladium on a support.
3. The process according to either or both of claims 1 and 2, characterized in that the amount of palladium catalyst is selected such that the molar ratio of palladium to 3, 3-dimethyl-2-hydroxybutyric acid or salt thereof used is between 1: 5 and 1: 20,000.
4. The process as claimed in one or more of claims 1 to 3, characterized in that activated carbon is used as support.
5. The process as claimed in one or more of claims 1 to 4, characterized in that the bismuth element and/or bismuth compound is employed in the form, for example, as an oxide, hydroxide, oxide hydrate or as a salt of a hydrogen acid, for example chloride, bromide, iodide, sulfide, or as a salt of an inorganic oxygen acid, for example nitrate, nitrite, phosphite, phosphate, carbonate, perchlorate, or as a salt of an oxygen acid which is derived from a transition metal, or as a salt of an organic acid or as a complex or as an organometallic compound.
6. The process as claimed in one or more of claims 1 to 5, characterized in that the amount of bismuth and/or bismuth compound is selected such that the molar ratio of bismuth and/or bismuth compound to 3, 3-dimethyl-2-hydroxybutyric acid or its salts is 1 x 10-6～1×10-1。
7. The process as claimed in one or more of claims 1 to 6, characterized in that bismuth and/or bismuth compounds are used in combination with other metals and/or semimetals or compounds thereof.
8. The process as claimed in one or more of claims 1 to 7, characterized in that the concentration of 3, 3-dimethyl-2-hydroxybutyric acid and its reaction products in the reaction solution is from 5 to 30% by weight.
9. The process according to one or more of claims 1 to 8, characterized in that the amount of base is selected such that a total of 1.1 to 8 equivalents of base is used per mole of 3, 3-dimethyl-2-hydroxybutyric acid used.
10. The process as claimed in one or more of claims 1 to 9, characterized in that the base used is an alkali metal or alkaline earth metal carbonate or hydroxide, a mixture thereof or a corresponding aqueous solution.
11. The process as claimed in one or more of claims 1 to 10, characterized in that the reaction is carried out at a pressure of from 0.1 to 50 bar.
12. The process according to one or more of claims 1 to 11, characterized in that the reaction is carried out at a temperature of 20 to 150 ℃.
13. The process according to one or more of claims 1 to 12, characterized in that the reaction is carried out at a temperature in the range of from 60 ℃ to the boiling point of the reaction mixture at the selected reaction pressure.
14. The process according to one or more of claims 1 to 13, characterized in that the reaction is terminated with an oxygen uptake of 0.4 to 0.6mol oxygen per mole of 3, 3-dimethyl-2-hydroxybutyric acid.
15. The process according to one or more of claims 1 to 14, characterized in that the obtained solution containing 3, 3-dimethyl-2-oxobutanoic acid predominantly in its salt form is used after partial or complete neutralization of the excess stoichiometric amount of base.
16. The process according to one or more of claims 1 to 15, characterized in that the 3, 3-dimethyl-2-oxobutanoic acid is obtained by acidifying the solution with mineral acids, such as hydrochloric acid, sulfuric acid and phosphoric acid, and subsequent extraction.
17. Use of 3, 3-dimethyl-2-oxobutanoic acid obtained by the process according to one or more of claims 1 to 16 for the preparation of agrochemicals.
18. The use as claimed in claim 17, characterized in that thiazoxazine is prepared.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE10236919.4 | 2002-08-12 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| HK1062012A true HK1062012A (en) | 2004-10-15 |
Family
ID=
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| KR101493293B1 (en) | Catalyst for preparing chlorine by oxidation of hydrogen chloride and preparation thereof | |
| CN1008088B (en) | Production of alcohols by hydrogenation of carboxylic acids | |
| EP0644173A1 (en) | Processes for producing 1,1,1,2,3-pentafluoropropene and producing 1,1,1,2,3-pentafluoropropane | |
| EP0019445B1 (en) | Process for the preparation of n-phosphonomethyl glycine | |
| JP5209941B2 (en) | Method for producing α, β-unsaturated ether | |
| WO2009115426A1 (en) | Method for preparing difluoroacetic acid and salts thereof | |
| CN1355783A (en) | Process for preparation of carboxylic acid salts from primary alcohols | |
| KR920005847B1 (en) | Method and catalyst for dehalogenation of α-halogenated carboxylic acids | |
| CN1040111C (en) | Manufacture of N-phosphonomethylglycine and its salts | |
| HK1062012A (en) | Process for preparation of 3, 3-dimethyl-2-oxobutyric acid | |
| JP6521498B2 (en) | Polyol-ether compound and method for producing the same | |
| US20040030186A1 (en) | Process for preparing 3,3-dimethyl-2-oxobutyric acid | |
| US4218380A (en) | Process for the preparation of arylglyoxylic acids | |
| HU181655B (en) | Process for preparing phenyl-glyoxylic acid | |
| JP4026350B2 (en) | Method for producing alkyl nitrite | |
| CN108203452B (en) | A kind of method of synthesizing sucralose-6-ethyl ester | |
| KR101535987B1 (en) | Preparation method of acetophenone | |
| CN1622926A (en) | Method for producing toluol derivatives | |
| KR20170090439A (en) | Catalytic oxidation of but-3-ene-1,2-diol | |
| GB2116063A (en) | Catalyst and process for producing methacrylic acid | |
| RU2541790C1 (en) | Method of obtaining glycolic acid | |
| CN1228415A (en) | Process for preparation of aqueous solutions of betaine | |
| EP1558597B1 (en) | Continuous process for the production of optically pure (s)-beta hydroxy-gamma-butyrolactone | |
| JP2958994B2 (en) | Methanol dehydrogenation catalyst | |
| CN115974677B (en) | Process for preparing glutaric acid |