JPS6210496B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel method for producing glutaraldehyde. Specifically, this is a method for producing glutaraldehyde, which is characterized by oxidizing 1,2-cyclopentanediol with air or oxygen using a cobalt compound as a catalyst. Glutaraldehyde is an extremely useful compound as a high-grade leather agent and as a disinfectant and disinfectant. Glutaraldehyde has conventionally been produced industrially by reacting acrolein with an alkyl vinyl ether to synthesize 2-alkoxy-3,4-dihydro-2H-pyran, which is then hydrolyzed. This method uses expensive raw materials and cannot be called an economical manufacturing method. Attempts have also been made to synthesize glutaraldehyde using cyclopentene, which is supplied more cheaply than the _C5 fraction, as a raw material. However, in many of the methods up to now, attempts have been made to synthesize glutaraldehyde by reacting cyclopentene or the 1,2 epoxycyclopentane obtained therefrom with an anhydrous hydrogen peroxide solution; This method is not suitable for practical use because it requires the above, is expensive, and uses dangerous hydrogen peroxide under anhydrous conditions. The inventors attempted to produce glutaraldehyde by oxidizing 1,2-cyclopentanediol. 1,2-Cyclopentanediol is easily obtained by oxidizing cyclopentene with peracetic acid or hydrogen peroxide solution. Synthesis of aldehydes by oxidative cleavage of vicinal diols such as 1,2-cyclopentanediol has been investigated mainly by reagent oxidation using lead tetraacetate, but such methods are expensive and expensive. In the case of oxygen oxidation, the yield of aldehyde was low because it was easily oxidized to carboxylic acid, and neither of them was suitable for practical use. The present inventors have developed a method using various metal compounds as catalysts.
As a result of detailed studies on the oxygen oxidation of 2-cyclopentanediol, the inventors discovered that glutaraldehyde can be synthesized in good yield by using a cobalt compound as a catalyst, thereby completing the present invention. 1・2
The synthesis of glutaraldehyde by oxidation of -cyclopentadiol is shown by the following formula. The only effective catalyst for glutaraldehyde synthesis is a cobalt compound, and manganese or nickel compounds commonly used in oxidation reactions yield no glutaraldehyde or only a very small amount. As the cobalt compound, cobalt chloride, cobalt carboxylate, or cobalt complexes such as cobalt acetylacetonate can be used. The amount of catalyst is 0.5 to 1,2-cyclopentanediol
10 mol% is suitable. The reaction temperature is preferably in the range of 60 to 140℃, especially 90 to 140℃.
A temperature of 110°C is preferred. Below 60°C, the reaction is extremely slow, and above 140°C, the oxidation reaction is slow and the yield decreases. Nitriles, amides, esters, etc. are suitable as the solvent. When 1,2-cyclopentanediol is oxidized with oxygen using a cobalt compound as a catalyst, the yield of glutaraldehyde increases as the reaction time progresses, but a side reaction occurs in which the aldehyde group is further oxidized to carboxylic acid, and glutaraldehyde is The yield reaches a maximum at a certain time. Generally, the lower the conversion rate of 1,2-cyclopentanediol, the higher the selectivity of glutaraldehyde, but if the conversion rate is too low, a large amount of 1,2-cyclopentanediol will be separated from the generated glutaraldehyde. It is important to choose the appropriate conversion rate and selectivity, which is necessary and not economical. The content of the present invention will be illustrated below with reference to Examples. Example 1 50 mmol of 1,2-cyclopentanediol,
2.48 mmol of cobalt decanoate in benzonitrile
The mixture was dissolved in 20 ml and reacted at 95°C by supplying air.
The time course of the reaction product is shown in figure -. reaction time
In 150 minutes, the conversion rate of 1,2-cyclopentanediol was 45% and the selectivity of glutaraldehyde was 83%. Example 2 Glutaraldehyde was synthesized by air oxidizing 1,2-cyclopentanediol at a reaction temperature of 95° C. and changing other reaction conditions. The results are shown in Table. 【table】

[Brief explanation of the drawing]

Figure 2 shows changes over time in reaction products and raw materials in Example 1. ●; 1,2-cyclopentanediol, ▲; glutaraldehyde, ■; carboxylic acid, vertical axis; 1.
2-cyclopentanediol, 100-conversion rate glutaraldehyde, yield, total yield of carboxylic acid, monocarboxylic acid and dicarboxylic acid, unit (%),
Horizontal axis: reaction time, unit (minutes).

Claims (1)

[Claims] 1. A method for producing glutaraldehyde, which comprises oxidizing 1,2-cyclopentanediol with air or oxygen in the presence of a cobalt compound.