KR810000879B1 - Process for preparing diaceton-2-keto-l-gulonic acid - Google Patents

Abstract

The catalyst for title compd. (I) was composed of NiCl2 contg. -20-50% NiNO3. Thus, 1.92 g NiCl26H2O and 1.28 g NiNO3.6H2O(mixing catalyst) were added to 100 g diaceton-L-sorbose in 50 ml H2O. The mixt. was oxidized with 33 g NaOH in 1.1l 9%-NaOCl at 50-60oC for 14-16min followed by removing the catalyst to gave 106.76g I(purity; 99.5%, yield; 95%).

Description

Method for preparing diacetone-2-keto-L-gulonic acid

The present invention relates to a catalyst used to prepare diacetone-2-keto-L-gulonic acid of the following structural formula (I) which is used as an intermediate raw material in the synthesis of batamine C.

To date, diacetone-2-keto-L-gulonic acid has been prepared by oxidizing diacetone-L-sorbose in alkaline sodium hypochlorite solution using a nickel salt or a cobalt salt as a catalyst. Nickel salts and cobalt salts used as catalysts are known to be catalyzed by black peroxide in sodium hypochlorite solution.

However, when the catalyst was used under the same reaction conditions, as shown in Table 1, the reaction time was long and the yield was low.

TABLE 1

※ Note: The reaction conditions other than the reaction temperature 50-60 ℃, catalyst concentration 0.2% are the same as in Example 1

The present inventors have conducted research experiments to compensate for these drawbacks of the prior art, and have prepared and used a mixed catalyst of nickel chloride containing about 20-50% (W / W) of nickel nitrate, compared to when using a conventional catalyst. As shown in Table 2, under the same reaction conditions, not only the reaction time was shortened, but also a powerful catalyst capable of increasing the yield was invented.

In more detail, the same catalyst concentration (0.2%, concentration =

When the mixed ratio of nickel nitrate and nickel chloride was changed to diacetone-L-sorbose at, the nickel nitrate or nickel chloride of the same catalyst concentration (0.2%) was used alone for diacetone-L-sorbose. It was possible to obtain diacetone-2-keto-L-gulonic acid in a higher yield in a shorter time than the case.

TABLE 2

※ Note: Reaction conditions other than catalyst composition and reaction time are the same as in Example 1.

As shown in Table 2, when a mixed catalyst of 40% nickel nitrate and 60% nickel chloride is used, the reaction time is about 1/4 of the same reaction conditions as that of using a single catalyst (see Table 2. Test Nos. 1 and 8). It is shortened and the yield is increased to 95%, which is a very advantageous method both economically and industrially.

The present invention will be described in more detail with reference to Examples.

Example 1

First, 100 g of diacetone-L-sorbose is dissolved in 500 ml of water, and 1.92 g of nickel chloride (NiCl ₂ .6H ₂ O) and 1.28 g of nickel nitrate (NiNO ₃ .6H ₂ O) are added thereto to make a solution. Then, a solution of 33 g of caustic soda dissolved in 1.1 L of 9% sodium hypochlorite solution was added to a 3 L three-neck round bottom flask, and the temperature was maintained at 50-60 ° C. while stirring.

Here, 500 ml of a solution of diacetone-L-sorbose and the catalyst dissolved in the above was added at a rate of 50 ml per minute for 10 minutes, and then reacted at 50-60 ° C. The reaction is completed in about 14-16 minutes after the addition of the catalyst. After completion of the reaction, the catalyst is filtered off, neutralized with concentrated hydrochloric acid solution and concentrated to 500 ml to produce sodium chloride. The solution was filtered to remove sodium chloride and then acidified to pH 1.0 with concentrated hydrochloric acid to precipitate fine crystals of diacetone-2-keto-L-gulonic acid. This was filtered again, washed and dried in vacuo to give 106.75 g of diacetone-2-keto-L-gulonic acid (melting point 98-99 ° C.) having a purity of 99.5%. Yield 95%

Example 2

2.4 g of nickel chloride in Example 1 and 0.8 g of nickel nitrate were used as catalysts and allowed to react for 30 minutes in the same manner as in Example 1, followed by neutralization. Concentration and acidification yield 102.3 g of diacetone-2-ketone-L-gulonic acid.

91% yield, 99.5% purity

Example 3

The reaction was carried out for 60 minutes in the same manner as in Example 1 using 2.88 g of nickel chloride and 0.32 g of nickel nitrate as a catalyst, followed by neutralization, concentration and acidification to obtain 103.38 g of diacetone-2-keto-L-gulonic acid.

Yield 92%, Purity 99.4%

Example 4

Diacetone-2-keto-L-gulonic acid having a melting point of 98-99 ° C after neutralization, concentration and acidification after reacting for 30 minutes in the same manner as in Example 1 using 2.56 g of nickel chloride and 0.64 g of nickel nitrate as a catalyst. Get 101.13g.

90% yield, 99.4% purity

Example 5

In Example 1, using 2.24 g of nickel chloride and 0.96 g of nickel nitrate as catalysts, the reaction was carried out in the same manner as in Example 1 for 30 minutes, and then neutralized. Concentrated and acidified. Diacetone-2-keto with a purity of 99.5% was obtained. 103.38 g of -L-gulonic acid is obtained. Yield 92%

Example 6

Using 1.6 g of nickel chloride and 1.6 g of nickel nitrate as catalysts, the reaction was carried out in the same manner as in Example 1 for 20 minutes, and then neutralized, concentrated and acidified to obtain 101.1 g of diacetone-2-keto-L-gulonic acid. 90% yield, 99.5% purity

Claims (1)

In the preparation of diacetone-2-keto-L-gulonic acid by oxidizing diacetone-L-sorbose in alkaline hypochlorite soda solution, a nickel chloride mixed catalyst containing 20-50% of nickel nitrate is used. Method for producing diacetone-2-keto-L-gulonic acid.