JPS5826733B2 - Ensocaldehydono Seizouhouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing 5-chlorovaleraldehyde.

More specifically, the present invention relates to a method for producing 5-chlorovaleraldehyde by reacting cyclopentanol with hypochlorous acid and/or hypochlorite.

5-chlorovaleraldehyde is a compound useful as an intermediate raw material for pharmaceuticals and organic compounds.

Conventionally, regarding the base of 5-chlorovaleraldehyde, δ
- Rosenmund reduction of 5-chlorovaleryl chloride obtained by reacting valerolactone and thionyl chloride in the presence of zinc chloride, or by reacting 5-chlorovaleryl chloride with N-methylaniline to obtain the corresponding N -Methylanilide and then reacting with lithium aluminum hydride (Y, Ban-T
-O1shi, Chem, Pharm-Bull,
11.446 (1963)), but all of these methods have the drawbacks of using expensive raw materials, long steps, and low yields of 5-chlorovaleraldehyde.

In addition, a method in which cyclopentanol and chlorine are reacted at 15° C. in an acetic acid-sodium acetate buffer solution under irradiation with tungsten light (N, C-Deno et al.

J-Org, Cbem-39, 520 (1974)).

Although this method is excellent, it generates a large amount of heat due to the simultaneous neutralization reaction of by-product hydrogen chloride, and since chlorine and by-product hydrogen chloride are present, there are problems in the selection of materials for the reactor.

In order to overcome these drawbacks, the present inventors have conducted intensive studies on the production method of 5-chlorovaleraldehyde, and have found that
The present invention was completed based on the discovery that 5-chlorovaleraldehyde is produced when cyclopentanol and hypochlorous acid and/or hypochlorite are reacted under mild conditions.

The process of the invention is characterized in that cyclopentanol is oxidized and chlorinated without the use of free chlorine.

According to the method of the present invention, hydrogen chloride, which causes large neutralization heat, is not substantially produced as a by-product, so that the reaction heat can be easily removed.

Furthermore, since corrosion of the material of the reactor due to chlorine and hydrogen chloride is suppressed, the advantages of the method of the present invention are immeasurable when considering industrial production.

This reaction is usually carried out under light irradiation, but 5-chlorovaleraldehyde is produced even in the absence of light.

The reaction temperature is -50~200℃, preferably 0~100℃
selected from the range.

The reaction proceeds by bringing cyclopentanol into contact with hypochlorous acid and/or hypochlorite.

This reaction is usually carried out in the presence of water.

The production of 5-chlorovaleraldehyde is observed regardless of whether the liquid is acidic, neutral, or basic; however, the yield of this aldehyde is particularly low when the reaction is conducted at a pH between weakly acidic and weakly basic, more preferably between pH 4 and 10. It is best when done within a range.

For this purpose, the reaction may be carried out in a suitable buffer solution, such as an acetate system.
It is preferred to carry out in the presence of an acidic phosphate system or to add an acid or base during the reaction to maintain the pH in the range indicated above.

The reaction may be carried out in the presence of an organic medium, and the raw material cyclopentanol itself may be used as the organic medium, but cyclopentanol itself, which is inert to hypochlorous acid and/or hypochlorite, may be used as the organic medium. Organic solvents such as halogenated hydrocarbons such as carbon tetrachloride; hydrocarbons such as hexane and benzene;
Nitrobenzene and the like can also be used.

Of course, these organic media and aqueous media may be used in combination.

Examples of the hypochlorite that can be used in this reaction include alkali metal or alkaline earth metal salts.

These hypochlorites are usually prepared by bubbling chlorine gas into an aqueous solution of an alkali metal or alkaline earth metal hydroxide prior to the reaction with cyclopentanol.

The molar ratio of hypochlorous acid and/or hypochlorite to cyclopentanol is usually 1:1, but hypochlorous acid or its salt is used in slightly excess chemical equivalent to cyclopentanol. Alternatively, a method of recovering unreacted cyclopentanol using less than an equivalent amount of hypochlorous acid or its salt can also be adopted.

Reaction time also varies depending on the reaction format.

When adding an aqueous solution of hypochlorous acid or its salt at an appropriate rate, the end point of the reaction may be the point at which the required amount of the aqueous solution of hypochlorous acid or its salt has been added; After finishing supplying the aqueous salt solution, the reaction may be continued further.

The reaction pressure is not particularly limited, but is usually normal pressure.

This reaction may be carried out at below atmospheric pressure or above atmospheric pressure.

The reaction is generally carried out by adding hypochlorous acid or hypochlorite to excess cyclopentanol, but it is also possible to perform the reaction by continuously mixing a predetermined amount of cyclopentanol and hypochlorous acid. It may be reacted.

EXAMPLES Next, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to the following Examples unless it exceeds the gist thereof.

Example 1 10.3 ft (0.12 mol) of cyclopentanol was added to a 500 rfL 15 large glass flask equipped with a thermometer, pH measuring device, dropping funnel, stirrer and condenser.
: and 20.4 ft (0.34 mol) of acetic acid and 49.2 ft (0.6 mol) of anhydrous sodium acetate.
Add 200 ml of an aqueous solution of sodium acetate containing 30 ml of sodium acetate, purify the system with nitrogen, put the flask in a water bath and keep it at 15°C, and while stirring the reaction mixture, heat the flask with a 200 W tungsten lamp from a distance of 30 crfL. Irradiated with 5% hypochlorous acid) IJium aqueous solution 15
Drop 0ml (0,099mol) in 30 minutes and add 3
Stirring was continued at the same temperature for 0 minutes.

The pH of the solution was 5.3 before the reaction started, and 5.3 at the end of the reaction.
It was 4.

When the reaction product was analyzed by gas chromatography, the conversion rate of cyclopentanol was 73.4%, and the selectivity of 5-chlorovaleraldehyde to converted cyclopentanol was 61.7%.

Example 2 A reaction was carried out in the same manner as in Example 1, except that 5% hypochlorous acid was used instead of sodium hypochlorite.

The conversion rate of cyclopentanol was 84.0%, and the selectivity of 5-chlorovaleraldehyde to converted cyclopentanol was 60.5%.

Example 3 Cyclopentanol 10.3 was added to the same apparatus as in Example 1.
? (0.12 mol), 5% sodium hypochlorite 1
50rIll (0,099mol), and water 1007
711 was added, and while stirring the reaction solution under light irradiation in the same manner as in Example 1, 1N hydrochloric acid was added to adjust the pn to 6.8, and the reaction was carried out at 15° C. for 1 hour.

The conversion rate of cyclopentanol was 65.0%, and the selectivity of 5-chlorovaleraldehyde to converted cyclopentanol was 46.7%.

Claims (1)

[Claims] 1. A method for producing 5-chlorovaleraldehyde, which comprises reacting cyclopentanol with hypochlorous acid and/or hypochlorite.