JPH0354094B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for synthesizing acetoacetate.

Acetoacetate is an important compound as an intermediate for dyes, pharmaceuticals, and other organic synthesis. Conventional industrial production methods include dehydrating acetic acid at 700°C using an aluminum phosphate catalyst to obtain ketene, cooling it under pressure to form diketene, and reacting the diketene with alcohol in the presence of a sulfuric acid catalyst. A method of synthesizing acetoacetate has been adopted. However, this method has the disadvantage that the reaction temperature is high and many reaction steps must be performed.

The object of the present invention is to provide a synthetic method for obtaining acetoacetate in high yield at low temperatures and in one step, without such drawbacks.

In order to achieve this objective, the inventor of the present application has conducted intensive research and has developed a method for synthesizing acetoacetate according to the present invention, which comprises reacting monohalogenated acetone, a lower alcohol, and carbon monoxide in the presence of a basic substance and a catalyst. Reached. That is, _{the method} of the present invention attempts to utilize _the following _reaction : (In the formula,
(X represents a halogen atom and R represents an alkyl group) The monohalogenated acetone used as a raw material in the present invention is preferably chloroacetone, but bromoacetone and iodoacetone can also be used.

As the alcohol, lower alcohols such as methyl, ethyl, propyl, isopropyl, and butyl alcohol are used.

Although pure carbon monoxide is preferable, inert noble gases or those containing a small amount of hydrogen can also be used. The partial pressure of carbon monoxide is 1 to 100 atm.
Preferably it is 1 to 50 atmospheres.

Basic substances include carbonates, bicarbonates, acetates, oxides of alkali metals and alkaline earth metals,
Hydroxides, alcoholates, tertiary amines such as triethylamine, and organic bases such as substituted pyridine are used, preferably sodium carbonate, potassium carbonate, triethylamine, lutidine and the like.

The amount of the basic substance used is greater than the theoretical value required to react with monohalogenated acetone as a raw material and equimolar hydrogen halide to produce a halide.

As the catalyst, dicobalt octacarbonyl is preferably used, but tetracobalt dodecacarbonyl, hydrocobalt tetracarbonyl and its sodium salt, cobalt carbonyl anion solution, etc. can also be used.

This is because all of these become Co(CO) ₄ ^- in the reaction system and exhibit catalytic action.

The amount of catalyst is 1/1000 to 1/5 mol, preferably 1/100 to 1/5 mol, per 1 mol of monohalogenated acetone.
10 moles are used.

Although the reaction proceeds without any particular solvent, organic solvents such as hydrocarbons, ethers, ketones, and esters can be used.

Furthermore, when an inorganic base is used, addition of an appropriate amount of water improves the reaction rate.

The reaction temperature is 10° to 150°C, preferably 30 to 70°C.

After the reaction, the autoclave is cooled, the reaction solution is taken out, and the catalyst and base are removed using a known method.
Acetoacetate can be obtained by distillation at normal pressure or under reduced pressure.

Next, examples of the present invention will be shown, but the present invention is not limited to the following examples unless it exceeds the gist of the present invention.

Example 1 2.5 ml (30 mmol) of monochloroacetone, 10 ml of ethanol,
Toluene 10ml, water 2ml, Na ₂ CO ₃ 2.1g
(20 mmol) and 0.6 g of Co ₂ (CO) ₈ were charged, and after purging the gas phase with carbon monoxide, carbon monoxide was pressurized to 10 Kg/cm ² .

When the reaction was carried out at 55° C. for 6 hours, the conversion rate of monochloroacetone was 88% and the yield of ethyl acetoacetate was 82% (based on the monochloroacetone starting material).

Example 2 The reaction was carried out at 55°C for 6 hours in the same manner as in Example 1 except that water was not added. The conversion of monochloroacetone was 12% and the yield of ethyl acetoacetate was 10%. Ta.

Example 3 In a 200 c.c. stainless steel autoclave, add 2.5 ml (30 mmol) of monochloroacetone, 20 ml of methanol,
Triethylamine 4.5ml (33mmol), _Co2
After charging 0.6 g of (CO) ₈ and purging the gas phase with carbon monoxide, carbon monoxide was pressurized to 30 kg/cm ² .

When the reaction was carried out at 55°C for 4 hours, the conversion of monochloroacetone was 93% and the yield of methyl acetoacetate was 76%.

Example 4 2.5 ml (30 mmol) of monochloroacetone, 20 ml of ethanol,
3.8 ml (33 mmol) of 2.6 lutidine and 0.6 g of Co ₂ (CO) ₈ were charged, and after purging the gas phase with carbon monoxide, carbon monoxide was pressurized to 30 kg/cm ² .

When the reaction was carried out at 55°C for 4 hours, the conversion of monochloroacetone was 63% and the yield of ethyl acetoacetate was 62%.

Example 5 A reaction was carried out at 55°C for 4 hours in the same manner as in Example 4 except that n-propanol was used as the alcohol, and the conversion rate of monochloroacetone was 62.
%, and the yield of n-propyl acetoacetate was 60%.

Example 6 In a 200 c.c. stainless steel autoclave, add 2.5 ml (30 mmol) of monochloroacetone, 20 ml of methanol,
2.6 di-tert-butylpyridine 7.4ml (33mmol),
0.6 g of Co ₂ (CO) ₈ was charged, and after purging the gas phase with carbon monoxide, carbon monoxide was pressurized to 30 kg/cm ² .

When the reaction was carried out at 55°C for 4 hours, the conversion rate of monochloroacetone was 23% and the yield of methyl acetoacetate was 23%.

Claims (1)

[Claims] 1. A method for synthesizing acetoacetate, which comprises reacting chloroacetone, a lower alcohol and carbon monoxide in the presence of a basic substance and dicobalt octacarbonyl. 2. The first lower alcohol is methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol or butyl alcohol.
How to combine terms. 3. The method of synthesis according to item 1, wherein the partial pressure of the carbon monoxide is 1 to 100 atmospheres. 4. The synthesis method according to item 1, wherein the basic substance is an organic base such as a tertiary amine, pyridine, or substituted pyridine. 5. The method of synthesis according to item 1, wherein the basic substance is an alkali metal or alkaline earth metal carbonate, bicarbonate, acetate, oxide, hydroxide, or alcoholate. 6 The reaction is carried out by adding an appropriate amount of water.
- Synthesis method according to any one of Items 5 to 5. 7. A method for the synthesis of acetoacetate, which comprises reacting chloroacetone, a lower alcohol and carbon monoxide in the presence of a basic substance and a sodium salt of dicobalt octacarbonyl or a solution of dicobalt octacarbonyl anion. 8. The synthetic method of item 1, wherein the reaction is carried out in a solvent.