JPS60139642A - Production of oxalyl fluoride - Google Patents

Abstract

PURPOSE:To produce the titled compound useful as a raw material for the production of various organic fluorine compounds such as perfluorodivinyl ether, etc., at a high rate of reaction, in high yield, simply by reacting oxalyl chloride with hydrogen fluoride in vapor phase. CONSTITUTION:Oxalyl chloride and hydrogen fluoride are heated and evaporated at a molar ratio of preferably 1:(2.2-10), and are made to react with each other in vapor phase at <=80 deg.C to obtain oxalyl fluoride. Since the water contained in hydrogen fluoride increases the production of by-products, it is preferable to use hydrogen fluoride having a water-content of <=0.1%.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to an efficient and simple method for producing oxalyl fluoride from oxalyl chloride.

Oxalyl fluoride is useful as JjK Fl for producing various organic fluorine compounds such as perfluorodivinyl ether. Furthermore, as a method for producing oxalyl fluoride, fluorination of oxalyl chloride is known. The fluorinating agent for oxalyl chloride is usually N a F
An alkali metal fluoride such as -1KF is used. In this case, the contact between the alkali metal fluoride and oxalyl chloride is carried out by suspending the alkali metal fluoride uniformly in a suitable neutral medium such as sulfolane, tetraglyme, or acetonitrile. The temperature is usually 130'U
Relatively high temperatures up to However, this method has the disadvantage that the reaction proceeds in the interphase of the same solution, so even if an alkali metal fluoride with a sufficiently small particle size is used, the reaction is very slow. Chemical compounds are expensive reagents, but it is a major industrial problem that only a fraction of the amount used is consumed. Furthermore, not only is the yield of the reaction low, but also fluorinated phosgene is likely to be produced as a by-product due to the high reaction temperature.

On the other hand, hydrogen fluoride is extremely cheap as a fluorination agent;
It was said that it had almost no reactivity with oxalyl chloride. Therefore, the present inventor has discovered that oxalyl fluoride can be obtained in good yield by reacting oxalyl chloride in a liquid phase with stirring that is more vigorous than the reaction activity limit, and has already proposed this method in Japanese Patent Application No. 55-141985. ). However, since the method L also requires special stirring conditions, there are problems in that the equipment becomes complicated and preliminary experiments are required to determine the Itl production conditions, which is cumbersome.

1-, ni! In view of this, the present inventor conducted further research and found that by simply reacting oxalyl chloride and hydrogen fluoride in the gas phase, the reaction rate was unexpectedly fast and the yield of H2-oxalyl fluoride was also improved. Knowing and observing the obtained facts, I was able to complete the present invention.

1! II. The present invention is a method for producing oxalyl fluoride, which is characterized by reacting oxalyl chloride and hydrogen fluoride in a gas phase. Therefore, in the present invention, the raw materials oxalyl chloride and hydrogen fluoride are each converted into gases and subjected to the reaction. Generally, oxalyl chloride and non-4I-hydrogen may be heated and vaporized, respectively, and then supplied in a gaseous state to a reactor and mixed. That is, since oxalyl chloride and hydrogen fluoride do not mix uniformly in a liquid state, the ? It is difficult to uniformly vaporize and react the R mixture.

Theoretically, 2 moles of hydrogen fluoride are required for each mole of oxalyl chloride in the raw materials listed below. However, as is generally practiced industrially, it is preferred to carry out the reaction with an excess of hydrogen fluoride, for example from 2.2 to 10 moles of hydrogen fluoride per mole of oxalyl chloride. in this case,
Excess hydrogen fluoride is recovered and reused after the reaction. In addition,
If hydrogen fluoride contains water, the yield of oxalyl fluoride, which is the secondary target of oxalic acid during the reaction with oxalyl chloride, will decrease, so it is generally not preferred. Particularly when carrying out a reaction using a large excess of hydrogen fluoride relative to oxalyl chloride, the presence of water in hydrogen fluoride becomes a big problem, so the moisture content of hydrogen fluoride, which is generally used suitably, is is preferably 0.5% or more, more preferably 0.5% or more. i% or less.

The reaction temperature of the present invention may be any temperature that allows at least oxalyl chloride to exist in a gaseous state. Therefore, even if the temperature is 2M degrees, which is considerably lower than the boiling point of oxalyl chloride, the oxalyl chloride can be entrained in an active gas such as nitrogen, helium, etc. with a sufficient flow rate, and then supplied to the reactor. You can also do that. However, since lowering the reaction temperature slows down the reaction rate, it is generally preferable to carry out the reaction at a temperature of 40° C. or higher. Furthermore, if the reaction temperature is too high, by-products such as phosgene fluoride are unavoidable, so it is generally preferable to maintain the temperature at 100° C. or lower, particularly at 8()° C. or lower.

In addition, the reaction pressure in the present invention is not particularly limited, and any of the following pressures can be used.

It is generally convenient to carry out near normal pressure.

Furthermore, the reaction time (the residence time of oxalyl chloride and unfluorinated i in the reactor) of the present invention varies depending on the reaction temperature, the quantitative ratio of oxalyl chloride and hydrogen fluoride, the addition ratio of inert gas, etc. However, it is extremely advantageous from a viewpoint of not reacting in a short period of time, generally 5 to 20 seconds, especially 1 to 10 seconds.

According to the present invention, the reaction yield of oxalyl fluoride from oxalyl chloride can be increased to 15% or more, and even 80% or more. The oxalyl fluoride produced by the reaction is distilled at low temperature by utilizing the difference in boiling point, melting point, etc. with hydrogen fluoride, hydrogen chloride, oxalyl chloride, and other oxalyl fluorides contained in the reaction gas. This allows the separation to be concentrated in a cold trap.

Examples will be shown below, but the present invention is not limited thereto.

Example 1゜ Oxalyl chloride and anhydrous hydrogen fluoride are vaporized at a rate of 15.0 g and 21.0 g per hour, respectively, and the temperature is controlled at 60°C. Cross-sectional area 2cI11, length 39c
The residence time is 1 to be supplied to the m+ stainless steel reactor.
1.5 seconds). The pressure inside the reactor was approximately 1 atmosphere.

The feed was continued for 2 hours, during which relatively low boiling components in the gas exiting the reactor were trapped by a dry ice-methanol bath immediately after the reactor. By rectifying this, oxalyl fluoride 20. ,．． 1g was obtained.

patent applicant Tokuyama Soda Co., Ltd.

Claims (1)

[Claims] υA method for producing oxalyl fluoride, which is characterized by reacting oxalyl chloride and hydrogen fluoride in a gas phase.