JPS5814414B2 - Method for producing cyclopentene-1-carbaldehyde - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for selectively producing cyclopentene-1-carbaldehyde from cyclohexene.

The oxime of cyclopentene-1-carbaldehyde is known to be useful as a sweetener (USP 37
801 94), and is also a useful substance as an intermediate for the synthesis of medicines, agricultural chemicals, dyes, and resin additives.

Cyclopentene-1-carbaldehyde is conventionally produced by intramolecular condensation of n-hexane dial, intramolecular condensation of 5-formylvaleric acid, ring condensation reaction of cyclohexene-3-hydroperoxide, or 2,3-epoxycyclo It is known that it can be synthesized by ring reduction reaction of hexanol.

However, these conventional methods require a large number of steps from the usual starting materials such as cyclohexene, cyclohexanediol, etc., and therefore cannot avoid high production costs.

The present inventors investigated the liquid phase oxidation reaction of cyclohexene in the presence of lower carboxylic acids and found that cyclopentene-1-carbaldehyde generates biothermal heat with high selectivity when bismuth sulfate containing water is used as a catalyst. They discovered this and arrived at the present invention.

That is, the gist of the present invention is characterized in that it is brought into contact with molecular oxygen or a gas containing molecular oxygen in a liquid phase in the presence of bismuth sulfate, water and a lower carboxylic acid at a temperature range of 40 to 150°C. A method for producing cyclopentene-1-carbaldehyde from cyclohexene.

The most important thing in the present invention is the quantitative relationship between bismuth sulfate and water in the reaction system.
It is necessary that water in the range of 0.2 parts to 2.5 parts per 00 parts be present.

When the coexisting amount of water is less than 0.2 parts, cyclopentene-
Almost no 1-carbaldehyde is produced, and most of the products are cyclohexenone-3 and cyclohexenol-3.

As the amount of coexisting water exceeds 0.2 part, the selectivity to cyclopentene-1-carbaldehyde increases, and when the amount of coexisting water exceeds 0.6 part, the selectivity exceeds 70%.

On the other hand, if the amount of water present exceeds 2.5 parts, the catalyst activity will be significantly reduced.

Therefore, the preferred range of coexisting amount of water is bismuth sulfate 10
The range is 0.6 to 2.5 parts per 0 parts.

Water, which plays an important role in the reaction of the present invention, can achieve the purpose of the present invention even if it is added to the reaction system separately from bismuth sulfate. It can also be added to the reaction system.

In the present invention, lower carboxylic acids are those having 2 to 6 carbon atoms,
Saturated aliphatic carboxylic acids or halogenated saturated aliphatic carboxylic acids, among which acetic acid, propionic acid, butyric acid or monochloroacetic acid are preferred.

The oxygen-containing gas used in the method of the present invention is a mixture of an inert gas (e.g. nitrogen) and oxygen,
It is desirable that the oxygen content is at least 5% (by volume).

To carry out the method of the invention, cyclohexene lower carboxylic acid, water and bismuth sulfate may be mixed and brought into contact with oxygen or an oxygen-containing gas while stirring.

The lower carboxylic acid is 0.0% by weight relative to cyclohexene.
Use 1 to 30 times.

Desirably, it is 0.5 to IO times.

Bismuth sulfate is used in the reaction solution in an amount of 0.005 mol/l or more, preferably 0.03 mol/l or more.

There is no significant difference in catalytic activity whether bismuth sulfate is added in powder form or granule form.

Although an increase in the amount of bismuth sulfate does not have an essential adverse effect on the reaction, if the amount exceeds 2.0 mol/l, it becomes difficult to stir the reaction solution.

The reaction can be carried out at a temperature range of 40 to 150°C, preferably 50 to 120°C.

The reaction can be carried out under normal pressure or under increased pressure, if necessary.

After the reaction is completed, the catalyst can be separated and the product can be isolated by a conventional method such as distillation.

Examples are shown below to explain the method of the present invention in more detail.

Example 1 Cyclohexene was added to a glass reactor. 0 ml, acetic acid 5. Oml and 0.7 g of bismuth sulfate containing 0.71% of adsorbed water were added, and the mixture was kept at 65° C. and brought into contact with oxygen at normal pressure for 5 hours.

After the reaction was completed, the reaction solution was analyzed using a gas chromatograph (PEG-2
The conversion rate of cyclohexene was 10.0M, 3M, 110℃). 3%, and the conversion rate to cyclopentene-l-carbaldehyde was 95%.

In addition, small amounts of cyclohexenone-3 and cyclohexenol-3 were detected.

In addition, cyclopentene-1-carbaldehyde can be measured by nuclear magnetic resonance absorption spectrum, infrared absorption spectrum, mass spectrometry,
and was able to be fixed by elemental analysis.

Example 2 10 ml of cyclohexene and 25 ml of propionic acid were placed in a stainless steel autoclave with an internal volume of 100 ml.
and bismuth sulfate 1,5 with 0.71% adsorbed water
g was added thereto, air was injected under pressure to show a pressure of 10 kg/cm' at 80°C, and the mixture was reacted at 80°C for 2 hours.

Analysis of the product by gas chromatography revealed that the conversion rate of cyclohexene was 11.7% and the selectivity to cyclopentene-1-carbaldehyde was 94%.

Example 3-6 Cyclohexene,
Predetermined amounts of a lower carboxylic acid and bismuth sulfate were added, and the mixture was kept at 65°C and brought into contact with oxygen at normal pressure for 5 hours.

After the reaction was completed, the results of gas chromatography analysis are shown in Table 1.

Comparative Example 1 5.0 ml of cyclohexene and 5.0 ml of acetic acid were placed in a glass reaction vessel. 0 ml and 0.7 g of bismuth sulfate (absorbed water content: 0) dried at 200°C for 3 hours were added, and the mixture was kept at 65°C and brought into contact with oxygen at normal pressure for 5 hours.

After the reaction was completed, the results of gas chromatograph analysis showed that
Cyclohexene conversion rate 1.6%, cyclohexenol 3, cyclohexenone-3, and cyclohexene-3
-Selectivity to hydroperoxide is 34% and 2, respectively.
5% and 15%.

Incidentally, cyclopentene-l-carbaldehyde was not observed.

In Comparative Example 1, 10 μl of water was added and stirred at room temperature for 30 minutes, and then brought into contact with oxygen at normal pressure at 65° C. for 5 hours.

After the reaction was completed, analysis by gas chromatography showed that
Cyclohexene conversion rate 7.7%, cyclopentene-1
- The selectivity for carbaldehyde was 93%.

Claims (1)

[Claims] 1. A method for producing cyclopentene-1-carbaldehyde, which comprises oxidizing cyclohexene in a liquid phase with molecular oxygen or a gas containing molecular oxygen in the presence of bismuth sulfate, water, and a lower carboxylic acid.