JPS5858335B2 - Alpha - Chikanacetone no Seizouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel method for producing α-monosubstituted acetone, which is useful as an intermediate for fragrances and agricultural chemicals.

The reaction formula of the method of the present invention is as follows.

M represents an alkali metal atom.

] Various methods can be considered for producing the ketone represented by the general formula, but conventionally, an acetoacetate represented by the general formula II) is prepared by preparing an alkali metal alcolade,
An alkylation reaction is carried out in the presence of an alkali metal amide or an alkali metal hydride, etc. to obtain the intermediate W, and after purifying (2) or unpurified, the next saponification and ketone decomposition reactions are carried out to obtain the target N. It was common to manufacture

In particular, when an alkali metal hydroxide is used in place of the alkali metal alcoholade, alkali metal amide, or alkali metal hydride from the safety and economic standpoints, the yield of intermediate (2) is extremely low and impractical. Ta.

In recent years, there have been reports of alkylating acetoacetate represented by general formula [I] using a quaternary ammonium salt as a phase transfer catalyst and using an alkali metal hydroxide as a condensing agent to obtain intermediate W. (A, B ri
ndstr6m etc. Acta Chem, S cand
.

23.2204 (1969).

In addition, a method to directly alkylate acetone using an alkali metal hydroxide as a condensing agent using a quaternary ammonium salt was also reported as a method for producing a ketone represented by the general formula N without using acetoacetate as a starting material. (Japanese Unexamined Patent Publication No. 4918818).

In technologies such as A and B rilindstr6m, it is essential to add quaternary ammonium salt as a catalyst, but this substance is easily soluble in water and has poor biodegradability, so the quality of wastewater deteriorates. That is clear.

The present inventors have also conducted extensive research into the production of α-monosubstituted acetone represented by the general formula General formula α] in aqueous solution as a condensing agent
The acetoacetic ester represented by is reacted with the halide represented by the general formula (9), and then saponification and ketone decomposition reactions are performed without removing any of the resulting intermediates to obtain the desired product in high yield. We succeeded in obtaining a certain α-monosubstituted acetone ``■'' and completed the method of the present invention.

The embodiments of the method of the present invention are as follows.

The acetoacetate used in the method of the present invention has the general formula C
Specific examples of the compounds represented by I) include methyl acetoacetate, ethyl acetoacetate, and the like.

Specifically, the halokene compounds used in the method of the present invention include allyl chloride, allyl bromide, allyl ionide, methallyl chloride, methallyl furomide, 1-chloro-2-butene, 1-7''romo-2-butene 1-ri Rolow 2-pentene, 1chloro-2-hexene, and so on.

The condensing agent used in the method of the present invention is an alkali metal hydroxide, and specific examples include lithium hydroxide, sodium hydroxide, and potassium hydroxide.

Of course, only one of these condensing agents may be used in some cases, but it is also possible to use two or more types in combination.

Also, lithium chloride, iodocalycum, lithium sulfate,
In some cases, the yield can be significantly improved by adding a catalytic amount of a salt such as lithium carbonate or sodium bromide.

Regarding the reagents used in the method of the present invention, some specific compounds have been illustrated above, but the compounds used in the method of the present invention include:
Of course, the compounds are not limited to those shown in the specific examples above.

There are no particular restrictions on the molar ratio of the reagents used in the method of the present invention, but the amount of halide used is 0.9 to 1.5 in molar ratio to acetoacetic ester, and the alkali metal hydroxide as a condensing agent. It is preferable to use a molar ratio of 2 to 3 to the acetoacetic ester, and the amount of water as a reaction solvent and the amount of salt added during the reaction can be varied within a very wide range.

Further, the reaction temperature can be arbitrarily selected within the range from room temperature to 110°C, and the addition of an organic solvent does not have any effect on the method of the present invention.

Next, the method of the present invention will be explained in more detail by way of examples.

Example 1 Methyl acetoacetate58. OS' (0.5 mol), Allylc0') t42.1? (0.55-El) and 100 ml of water were charged into 50011114 flasks.

While stirring and maintaining the internal temperature at 40 to 45° C., 35% aqueous sodium hydroxide solution 1439 (1.25 mol) was added dropwise over 3 hours.

After the addition is complete, continue stirring at that temperature until the internal temperature reaches 78.
The mixture was gradually heated to 78°C and the reaction was carried out for 2 hours.

After the reaction was completed, steam distillation was performed while water was added dropwise, and the distillate was separated to collect crude allylacetone in the upper layer.

By rectifying this crude allyl acetone, the purity is 99%.
Allyl acetone (b, p, 132°C) 31.1'
I got it.

This was a 75% yield based on methyl acetoacetate.

Example 2 Methyl acetoacetate 58.0'? (0.5 mol), allyl chloride 42. IP (0.55 mol), lithium hydroxide-hydrate 4.2'ff, water 1001 rLl in 500 m
A'Pour into the fourth flask and keep stirring until the internal temperature is 40℃.
heated until.

Add to this 35% sodium hydroxide aqueous solution 143f (1,2
5 mol) was added dropwise over 2 hours while maintaining the internal temperature at 40 to 45°C.

After completion of the dropwise addition, stirring was continued for a while at 40 to 45°C, then gradually heated until the internal temperature reached 80°C, and the reaction was carried out at that temperature for 2 hours.

Thereafter, the same operations as in Example 1 were performed to obtain highly pure allyl acetone at a yield of 85% based on methyl acetone.

Example 3 Ethyl acetoacetate 65.1' (0.5 mol), allyl chloride 40.21 (0,525 mol), lithium chloride 2
．． 2, 1001'IL of water was charged into 14 500 m flasks.

While maintaining the internal temperature at 40 to 45°C, 192'ft (1.2 mol) of a 35% aqueous potassium hydroxide solution was added dropwise over 2 hours.

After dropping, gradually heat until the internal temperature reaches 80°C.
The reaction continued at that temperature for 2 hours.

After that, the same operations as in Example 1 are performed.

80% of high purity allyl acetone to ethyl acetoacetate
% yield.

Example 4 Methyl acetoacetate 58.0 P (0.5 mol), methalyl chloride 49,1' (0.55 mol), lithium hydroxide-hydrate 4.21, water 100 ml to 500 ml
I put it in a double flask.

35% hydroxide while keeping the internal temperature at 40-50'C)
An IJium aqueous solution 143y' (1.25 mol) was added dropwise over a period of 2 hours.

After the dropwise addition was completed, the mixture was gradually heated to an internal temperature of 80° C., and the reaction was continued at that temperature for an additional 2 hours.

After the reaction is complete, the contents of the flask are transferred to a separating funnel, the upper organic layer is taken, dried over anhydrous sodium sulfate, and then rectified to convert methalylacetone (b, p, 145-150°C) into methyl acetoacetate. It was obtained with a yield of 85%.

Example 5 A reaction was carried out under the same conditions as in Example 4 except that the following chloride was used in place of metaallyl chloride in Example 4.

The results are shown in the table below. Example 6 The same operation as in Example 2 was carried out except that the time for lowering the 35% sodium hydroxide aqueous solution (2 hours) was changed to 30 minutes, and the target allylacetone was converted into acetone methyl acetate. It was obtained with a yield of 77%.

Claims (1)

[Claims] 1 General formula