JPS6151575B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing high purity bromonitroalcohol in high yield.

It is known to date to produce bromonitroalcohols by addition reaction of nitromethane and formaldehyde and then bromination of the product. For example, a method in which the two are subjected to an addition reaction in the presence of an alkali metal alcoholate in anhydrous alcohol, the alkali salt of the resulting nitroalcohol is separated, and then brominated in a nonpolar solvent [Berichte 56 , 611 (1923 ], an addition reaction between an alkaline earth metal chloride and an alkali or alkaline earth metal hydroxide in an aqueous solution;
A method of brominating the alkaline earth metal salt of the produced nitroalcohol without separating it (West German Patent Application No. 1768976 and No. 1804068), in which both are brominated in the presence of an alkaline earth metal hydroxide in an aqueous solution. Method of addition reaction followed by bromination (JP-A-Sho)
48-72108), a method in which both are subjected to an addition reaction in the presence of a chemical equivalent of alkali hydroxide in an aqueous solution, and then bromination (Japanese Patent Publications No. 49-20761 and 50-
No. 7577), when performing an addition reaction between an alkaline earth metal chloride and an alkali or alkaline earth metal hydroxide, the amount of the alkali or alkaline earth metal hydroxide is 1.3 to 1.4. A method of suppressing the formation of by-products with a large number of aldehyde bonds by using an excess amount in the molar range (Japanese Patent Application Laid-open No. 70911/1983), in which both are subjected to an addition reaction in the presence of an alkali carbonate, and then bromination is performed. A method (Japanese Unexamined Patent Publication No. 52-3011) has been proposed.

However, with these methods, the yield of the desired bromonitroalcohol is low at 85% or less, and condensates, dibromo-forms, monoalcohol adducts, etc. are produced as by-products, so it is difficult to produce bromonitroalcohol on an industrial scale. In this case, by-products must be removed, and this purification process is complicated, which inevitably increases production costs.

As a result of extensive research to develop a method for producing high-purity bromonitroalcohol with high yield, the present inventors found that conventional methods have a high boiling point, a large number of functional groups, and are prone to side reactions. When an alkane polyol, which is rarely used as a solvent, is used as a solvent, the desired bromonitroalcohol is produced with a high yield of 98-99%, and high purity bromonitroalcohol can be produced without a special purification process. It was discovered that alcohol can be obtained, and based on this knowledge, the present invention was accomplished.

That is, the present invention uses 1 mole of nitroalkane and 2 moles of aldehyde represented by the general formula RCHO (1) (wherein R is a hydrogen atom or a methyl group) using an alkane polyol as a solvent, A general formula characterized by reaction in the presence of an alkali catalyst followed by bromination of the product. (R in the formula has the same meaning as above) A method for producing bromonitroalcohol represented by the following is provided.

Examples of the alkali catalyst used in the method of the present invention include alkali metal hydroxides such as sodium hydroxide, potassium hydroxide, and lithium hydroxide; alkali metal carbonates such as sodium carbonate, potassium carbonate, and lithium carbonate; These include alkaline earth metal hydroxides such as calcium.

Examples of the alkane polyol used as a solvent include alkanediols such as ethylene glycol, diethylene glycol, and propylene glycol, and alkane triols such as glycerin, with diethylene glycol being particularly preferred.

In the present invention, it is necessary to use nitromethane and aldehyde in a molar ratio of 1:2, but if desired, aldehyde can be used in excess. In this way, a diol in which two aldehyde molecules are added to one nitromethane molecule is produced.

The alkali catalyst is preferably used in an approximately equivalent amount to the nitroalkane, but it can be used in slightly excess if desired. However, if the amount of the alkali catalyst is extremely excessive, the target substance, bromonitroalcohol, becomes unstable, which is not preferable.

The amount of alkane polyol used as a solvent is 3 to 7 times the weight of nitromethane, preferably 5 times the weight of nitromethane.
~6.5 times the weight.

The addition reaction of nitromethane and aldehyde is carried out by mixing the two and stirring for 1 to 24 hours, resulting in a quantitative yield of the alkali salt of the nitroalcohol.

The bromination of this product is carried out without isolating the alkali salt of the nitroalcohol from the reaction mixture by adding bromine thereto at a temperature of 5 DEG to 20 DEG C. Since this bromination reaction also proceeds quantitatively, the equimolar amount of nitromethane, which is the starting material, is sufficient as the amount of bromine used, but if desired, excess bromine can be used.

After the bromination reaction is completed, the solution is neutral or weakly acidic, and the produced bromonitroalcohol is stable.

According to the method of the present invention, bromonitroalcohol can be produced almost quantitatively, and not only can highly purified bromonitroalcohol be obtained without going through complicated purification steps, but also
The method of the present invention is suitable for implementation on an industrial scale because it is highly safe due to the low volatility and flammability of the solvent.

Next, the present invention will be explained in more detail with reference to Examples.

Example 1 18.3 g (0.3 mol) of nitromethane and 48.7 g (0.6 mol) of 37% formalin were mixed with diethylene glycol.
100g, cool the resulting solution to 5℃, then add 3ml of 40% sodium hydroxide aqueous solution while stirring, the temperature of the solution will rise to 40℃, and then quickly rise to room temperature (25-30℃). It started to drop, so I stirred it for another hour at this temperature.
When an additional 28.8 ml of 40% aqueous sodium hydroxide solution was added dropwise, colorless crystals of sodium salt of 2-nitro-1,3-propanediol were precipitated. of solution
The pH was 13.2. Cool the solution to 5°C,
While stirring, 47.9 g (0.3 mol) of bromine was added dropwise. The temperature of the solution was maintained at 5-20°C. After the dropwise addition of bromine was completed, the solution took on a slightly yellow color and the pH was 4.4.

This solution was subjected to gas chromatography,
The yield of 2-bromo-2-nitro-1,3-propanediol based on nitromethane was determined.

That is, the sample solution was previously silylated in dehydrated pyridine using 1,1,1,3,3,3-hexamethyl-disilazane and chlorotrimethylsilane, and then subjected to chromatography.

Conditions for gas chromatography Equipment: Gas chromatograph with FID detector Column: Glass column 1.5m Packing material: Liquid phase Silicon GE-XE60 3.0% Support Chromosolve W-AW-DMCS 60-80mesh Column bath temperature: 140℃ Carrier gas: N ₂ As a result of analysis by gas chromatography at 55 ml/min, the yield based on nitromethane was 99.8%.

Next, this solution was distilled under reduced pressure to remove diethylene glycol, then 200 ml of water was added, saturated with common salt, and extracted 5 times with ethyl acetate. The residue was distilled off to obtain crude crystals of 2-bromo-2-nitro-1,3-propanediol. This was recrystallized from a mixture of 1 part ethyl acetate and 2 parts chloroform to obtain 58.8 g of pure product as colorless columnar crystals. Melting point 127-129
Yield 98.0% based on °C nitromethane Example 2 2-Bromo-2-nitro-
1,3-propanediol was produced. Example 1
The yield was determined by gas chromatography under the same conditions as in 2008 and found to be 99.0%.

Example 3 2-bromo-2-nitro-1,3-propanediol was produced in the same manner as in Example 1, except that 100 g of propylene glycol was used as the solvent instead of 100 g of diethylene glycol. The yield was examined by gas chromatography under the same conditions as in Example 1 and found to be 98.0%.

Example 4 Example 1 except that 100 g of glycerin was used instead of 100 g of diethylene glycol as the solvent.
Similarly, 2-bromo-2-nitro-1,3-
Propanediol was produced. The yield was examined by gas chromatography under the same conditions as in Example 1 and found to be 98.8%.

Example 5 By using 26.5 g of acetaldehyde instead of formalin in Example 1 and carrying out the reaction in the same manner as in Example 1 except for the other conditions, 3-bromo-3
-Nitropentane-2,4-diol was obtained. The yield was 96.8%.

Claims (1)

[Claims] 1. 1 mole of nitromethane and 2 moles of an aldehyde represented by the general formula RCHO (R in the formula is a hydrogen atom or a methyl group) are mixed in the presence of an alkali catalyst using an alkane polyol as a solvent. The general formula is characterized in that the product is brominated after reacting with (R in the formula has the same meaning as above) A method for producing bromonitroalcohol represented by: 2. The method according to claim 1, wherein the alkali catalyst is an alkali metal hydroxide or carbonate. 3 The alkane polyol is ethylene glycol,
The method according to claim 1, wherein diethylene glycol, propylene glycol or glycerin is used.