JPS6263547A - Production of trimethylolethane trinitrate - Google Patents

Abstract

PURPOSE:To produce the titled compound easily by sulfating trimethylol while keeping the relative concentration of a polymeric polyhydric alcohol sulfate produced together with trimethylolethane sulfate below a specific level determined by light absorbance. CONSTITUTION:Trimethylolethane is dissolved in sulfuric acid (preferably 50pts. wt. of trimethylolethane is dissolved in 150-300pts.wt. of 80-98% sulfuric acid at 20-60 deg.C) to effect the esterification reaction. The reaction is carried out under a condition to give a reaction product having an absorbance of <=2 at 370nm. The objective trimethylolethane trinitrate obtained by the nitration of the trimethylolethane sulfate is useful as a nitrated plasticizer for propellant and the propellant produced therefrom has excellent thermal stability.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to (2) a method for producing trimethylolethane trinitrate, which is used as a plasticizer in propellants and the like. For more information, see Safe and easy post-processing.
The invention also relates to a method for producing trimethylolethane trinitrate which has excellent thermal stability.

(Prior Art) Trimethylolethane trinitrate is obtained by nitrating trimethylolethane. Trimethylolethane is a polyhydric alcohol, and the nitration of polyhydric alcohols is generally carried out by 1) a method of charging the polyhydric alcohol in concentrated nitric acid (Japanese Patent Publication No. 1983-9532); 2)
Method of adding sulfuric acid after nitrification with nitric acid (published by the Industrial Explosives Association, "Industrial Explosives Co., Dan 214-216 (1961)"
), 3) A method of charging a mixture of sulfuric acid and nitric acid, 4) A method of reacting a sulfuric acid ester of a polyhydric alcohol in a mixture of sulfuric acid and nitric acid ("Industrial Explosives" published by the Industrial Explosives Association)
, Tan 214-216 (1961)), etc.

(Problems to be Solved by the Invention) When trimethylolethane is nitrated by the above-mentioned known method, since trimethylolethane is a solid at room temperature, in the above-mentioned methods 1) to 3), the reaction is carried out in a solid phase. Since the reaction is a heterogeneous reaction between one liquid phase, local heating occurs at the interface between the solid phase and the liquid phase, making safe production difficult.

In comparison, method 4) first esterifies trimethylolethane with sulfuric acid, so the nitration reaction is carried out in the liquid phase, and the reaction is a homogeneous reaction 1), which reduces the risk of local heating and is safe. be. However, in the production of sulfuric acid ester, trimethylolethane is dissolved in sulfuric acid, so dehydration reactions tend to occur at this time, and in addition to the desired trimethylolethane sulfate ester, sulfuric ester of a polymeric polyhydric alcohol is produced, and the reaction conditions In severe cases, the dehydration reaction results in carbon-rich compounds, ie carbonization.

The amount of this polymeric polyhydric alcohol sulfate ester produced varies depending on slight conditions of the esterification reaction. When producing trimethylolethane nitrate by nitrating the sulfate ester of trimethylolethane in which the sulfate ester of these polymeric polyhydric alcohols coexists, safety during production, separation workability during product washing, and heat Stability deteriorates.

The present inventors conducted intensive research to develop a method for producing trimethylolethane sulfate ester and then nitrating it without the above-mentioned drawbacks. The sulfate ester of alcohol needs to be kept below a certain amount, and the certain amount can be easily determined by the absorbance value obtained by visible ultraviolet absorption spectroscopy, and the amount of sulfate ester (trimethylolethane) below that absorbance value can be easily determined. The trimethylolethane trinitrate obtained by nitrating the sulfate ester of the sulfuric acid ester with the coexistence of the sulfuric ester of a polymeric polyhydric alcohol can be easily washed and separated. The present invention was completed based on findings such as good thermal stability.

(Means for Solving the Problem) The present invention provides a method for producing trimethylolethane trinitrate by dissolving trimethylolethane in sulfuric acid to produce a sulfated ester of trimethylolethane, and then nitrating it to produce trimethylolethane trinitrate. The present invention relates to a method for producing trimethylolethane trinitrate, which is characterized by producing a sulfuric ester having an absorbance value of 2 or less at 370 nm as measured by absorption spectroscopy.

In the present invention, the relative concentration of the sulfur ester of a polymeric polyhydric alcohol that is produced together with trimethylolethane sulfate when trimethylolethane is sulfuric esterified is determined by measuring its absorbance value using visible ultraviolet absorption spectroscopy. By keeping the measured value below 2, stable production became possible. That is, the visible ultraviolet absorption spectrum of sulfuric ester of trimethylolethane is 370 n
It has an absorption peak near m, increases in proportion to the concentration of 1,000 ster sulfate of high-molecular polyhydric alcohol, and reflects the rate of carbonization, which can be judged from the appearance. Furthermore, even if the sulfuric acid concentration used for sulfuric acid esterification of trimethylolethane differs, the absorption peak does not shift, and various sulfuric esters can be treated in the same way.

Based on the above, in the present invention, trimethylolethane is first dissolved in sulfuric acid and esterified, but this esterification reaction is carried out under conditions such that the absorbance value at 370 nm of the reaction product is 2 or less. Trimethylolethane trinitrate can then be obtained by nitration in a conventional manner, for example with a mixture of sulfuric acid and nitric acid, such as 47 parts by weight of sulfuric acid, 54 parts by weight of nitric acid, and 1 part by weight of water.

The conditions under which the absorbance value at 370 nm of the esterification reaction product is 2 or less are based on the results of the Ume-Ume experiment.
0 to 300 parts by weight are reacted at 20 to 60°C. If the amount of sulfuric acid is too small, the viscosity of the sulfuric acid ester solution will be high, and the dropping process during nitrification will take time, which is impractical. If the amount is too high, dehydration reaction will occur and high-molecular polyhydric alcohol will easily be produced, and if nitrification occurs, the amount of reaction liquid will be large and the amount of trimethylolethane trinitrate produced per batch will be reduced. .

If the temperature is low, esterification is slow and impractical, and if the temperature is high, sulfuric acid esters of polymeric polyhydric alcohols are produced, resulting in poor production safety, separation workability during chemical cleaning, etc.
Thermal stability of chemicals deteriorates.

(Effects of the Invention) According to the present invention, trimethylolethane trinitrate can be produced safely, post-treatment is simple, and the produced product has excellent thermal stability.

(Example) Next, the present invention will be further explained in detail by giving examples and comparative examples.

Example 1 50 parts by weight of trimethylolethane was dissolved in 150 parts by weight of 90, 95, and 97X sulfuric acid at a temperature of 60°C to carry out a sulfation esterification reaction. Next, the visible ultraviolet absorption spectrum of each ester was measured using water as a control solvent. The results are shown in the drawing. In the figure, the sulfuric acid concentration is 90% and 95N for /, ko, and 3, respectively.
, 97X is shown. 370nm
The absorbance at 0.2, 0.7, and 1.3, respectively.
It shows that. These sulfuric esters were added to 365 parts by weight of a mixture of sulfuric acid and nitric acid (47 parts by weight of sulfuric acid, 54 parts by weight of nitric acid, 1 part by weight of water) and nitrated to produce trimethylolethane trinitrate as a nitration reaction product. A reaction solution containing the following was obtained. This reaction solution is poured into cold water to separate trimethylolethane trinitrate. After removing the waste acid in the upper layer, the trimethylolethane trinitrate is stirred and washed with warm water. At this time, since the trimethylolethane trinitrate was finely divided, the hot water and the produced trimethylolethane trinitrate were separated by standing. This separation is about 5
minutes, about 12 minutes, about 20 minutes.

(Thermal stability test of reaction solution containing tatrimethylolethane trinitrate obtained by nitrating a mixture of sulfuric acid and nitric acid) *1 1. When the absorbance of the esterified product is 0.2, 50°C
It remained stable without decomposition for 2 days.

When the absorbance of the muester compound was 1.6, severe decomposition Z occurred after 36 hours at 50°C.

(Heat resistance test of trimethylolethane trinitrate)
*2 When using sulfuric ester with absorbance of 0.2, 82.
At 2℃, it is stable for 16 minutes.

(Composition of the obtained trimethylolethane trinitrate) Water content: 0.2% by weight or less, acid content and alkali content: 0.002% by weight or less.

Comparative example? Trimethylolethane trinitrate was produced under exactly the same conditions as in Example except that sulfuric acid was used and the dissolution temperature of trimethylolethane in sulfuric acid was 75°C. The absorbance of the esterified product during this production was 9.4.

Separation of the hot water and the produced trimethylolethane trinitrate in this comparative example required 2 hours.

(Thermal stability test of reaction solution containing trimethylolethane trinitrate obtained by nitrating a mixture of sulfuric acid and nitric acid) Decomposition started after 25 hours at 50°C.

(Heat resistance test of trimethylolethane trinitrate)
It took 4 minutes at 82-2°C.

The above-mentioned thermal stability test and heat resistance test were conducted in the following manner.

That is, in the thermal stability test, a three-bottle flask containing 500 f of the reaction solution was placed in a glycerin bath at a temperature of 50°C, and the temperature change and time until decomposition of the reaction solution were measured while stirring the reaction solution. Heat resistance test: inner diameter 117cm, outer diameter 15cm
．． Place 2 rIt of sample in a test tube of 8 m and length 140 ttm.
Put a rubber stopper on it with iodopotash starch paper 10cm wide and 255m long. Next, this was placed in a constant temperature bath of 822° C. glycerin/water = 50150 (volume ratio), and the time until the iodopotash starch paper changed color was determined.

[Brief explanation of the drawing]

The drawings are examples, and the sulfuric acid concentration is 9ON, 95%, 9
An absorbance curve showing the relationship between wavelength and absorbance when the wavelength is changed to 7% is shown. In the figure, / is -90%, and / is 95X.
, 3 indicates the case of 97N.

Claims (2)

[Claims] (1) In a method for producing trimethylolethane trinitrate by dissolving trimethylolethane in sulfuric acid to produce a sulfuric ester of trimethylolethane and then nitrating it, the absorbance value at 370 nm by visible ultraviolet absorption spectroscopy is 2. A method for producing trimethylolethane trinitrate, characterized by producing the following sulfuric ester. (2) For 150 to 300 parts by weight of 80 to 98% sulfuric acid,
Trimethylolethane trinite according to claim 1, which produces a sulfuric ester having an absorbance value of 2 or less at 370 nm as determined by visible ultraviolet absorption spectroscopy by dissolving 50 parts by weight of trimethylolethane at 20 to 60°C. How to make rate.