JPH0121821B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention is directed to the use of a mixture of decomposition products obtained by decomposing 1,2-dichloropropane, mainly consisting of allyl chloride and chloropropenes, to produce carboxyl This is a method for preventing corrosion of reaction equipment when producing allyl esters by reacting with acids.

(Prior art) 1,2-dichloropropane is produced as a by-product during the production of allyl chloride by high-temperature chlorination of propylene, and suppressing the by-product of 1,2-dichloropropane is important for reducing the production of allyl chloride and propylene. This is essential for improving the basic unit in the oxide manufacturing industry. Nevertheless,
The amount of by-product 1,2-dichloropropane is considerable, and the effective use of this by-product 1,2-dichloropropane has become an important issue for improving the basic unit of production in these manufacturing industries.

By the way, regarding the effective use of 1,2-dichloropropene, its main uses are as an inexpensive solvent such as nematicide, a solvent for 1,3-dichloropropane, asphalt for pavement, and a solvent for oils and fats. It is something.

However, 1,2-dichloropropane is a halogenated hydrocarbon, and its use as a solvent is subject to safety restrictions.

In addition, research has been conducted to obtain allyl chloride by dehydrochlorinating 1,2-dichloropropane, but usually, dehydrochlorinating 1,2-dichloropropane produces allyl chloride, 1-chloropropene (cis, (trans) and 2-chloropropene are produced, and it is difficult to separate and purify them from each other. For example, among these, allyl chloride (reaction rate 50-90%, selectivity 40-70%), which is highly useful as an industrial raw material and is produced in relatively large quantities, cannot be isolated from these mixtures on an industrial scale. ,
The cost required for this is higher than the cost of directly chlorinating propylene to produce allyl chloride,
The method of dehydrochlorinating 1,2-dichloropropane to obtain allyl chloride is not a practical method. Therefore, attempts have been made to use these mixtures as industrial raw materials, but for example,
In the chlorohydrination reaction, not only allyl chloride but also chloropropenes react, and the reaction product becomes a mixture, which requires isolation and purification as in the case of decomposition products.

As seen above, the reality is that 1,2-dichloropropane is not utilized effectively.

(Problems to be Solved by the Invention) Under such circumstances, the present inventors selected allyl chloride from the thermal decomposition products containing allyl chloride and chloropropenes as an effective use of 1,2-dichloropropane. As a result of investigating a method of reaction, it was found that by reacting an alkali metal salt of a carboxylic acid, or a carboxylic acid or carboxylic acid anhydride with an alkali metal carbonate, allyl chloride can mainly be converted into allyl esters ( Patent application No. 114286 (Sho 58-114286).

However, this reaction is accompanied by significant corrosion of the reactor, and has the problem that ordinary materials such as iron and stainless steel cannot be used, but high-grade materials such as titanium and high-nickel steel are required. This corrosion is greater in the case of the above thermally decomposed product than in the case of using the commercially available allyl chloride. The cause of corrosion is not clear, but it is thought to be trace amounts of hydrogen halide generated in the raw materials or during the reaction.

(Means for Solving the Problems) As a result of various studies in order to solve these problems, the present inventors found that a decomposition product consisting mainly of allyl chloride and chloropropenes obtained by decomposing 1,2-dichloropropane When reacting alkali metal salts of carboxylic acids or carboxylic acids and/or carboxylic acid anhydrides with alkali metal carbonates as a mixture, adding 0.3 to 3.0% by weight of water to the decomposition products. It was discovered that the corrosion protection effect of the reactor can be significantly improved by
After further research, the present invention was completed.

The decomposition product of 1,2-dichloropropane used in the method of the present invention can be obtained by thermally decomposing 1,2-dichloropropane in the presence or absence of a catalyst, or
Obtained by reacting with an alkali.

Moreover, any common carboxylic acid can be used as the carboxylic acid used in the method of the present invention.
Examples include phthalic acid, isophthalic acid, terephthalic acid, benzoic acid, naphthalene dicarboxylic acid, maleic acid, nitrophthalic acid, chlorobenzoic acid, succinic acid, cinnamic acid, glutaric acid, itaconic acid, and the like. Moreover, as the alkali metal salt of the above-mentioned carboxylic acid, sodium salt and potassium salt are preferable. Furthermore, a carboxylic acid and/or a carboxylic acid anhydride and an alkali metal carbonate can be used instead of an alkali metal salt of a carboxylic acid.

1, in the presence or absence of a catalyst to an alkali metal salt of a carboxylic acid or a carboxylic acid and/or a carboxylic acid anhydride and an alkali metal carbonate;
The decomposition product of 2-dichloropropane is fed all at once or continuously, and allyl chloride in the decomposition product of 1,2-dichloropropane is reacted.

In the method of the present invention, water may be added all at once at the beginning of the reaction or continuously during the reaction.
From the viewpoint of corrosion prevention effect, it is preferable to add it all at once at the beginning of the reaction.

The amount of water added is preferably 0.3 to 3.0% by weight, and 0.3% by weight based on the decomposed product of 1,2-dichloropropane.
If it is less than 3.0% by weight, the corrosion resistance will be insufficient, and if it exceeds 3.0% by weight, the yield will decrease due to decomposition of allyl chloride, etc.

The reaction conditions vary depending on the type of carboxylic acid, but generally the reaction pressure is preferably 0 to 10 kg/cm ² G and the reaction temperature is about 130 to 200°C. Further, the reaction may be carried out while removing unreacted chloropropenes from the reaction system during the reaction, or may be removed all at once after the reaction is completed.

(Function) In the method of the present invention, the decomposition products obtained by decomposing 1,2-dichloropropane, mainly consisting of allyl chloride and chloropropenes, are reacted as a mixture with carboxylic acids to produce only allyl chloride. Allyl esters can be selected.

In addition, by adding 0.3 to 3.0% by weight of water to the 1,2-dichloropropane decomposition product, it exhibits virtually complete corrosion resistance against stainless steel, and industrially inexpensive reaction equipment can be used. It becomes possible.

Furthermore, unreacted chlorpropenes can also be isolated, and chlorpropenes with a purity that can be used industrially can be obtained.

Therefore, according to the method of the present invention, 1,2-dichloropropane, which has not been effectively utilized in the past, can be used industrially advantageously.

In addition, in the method of the present invention, the reaction rate and yield of allyl chloride in the decomposition product of 1,2-dichloropropane are comparable to those of pure allyl chloride.

(Examples) The present invention will be explained in detail with reference to Examples and Reference Examples.

Reference Example (Thermal decomposition of 1,2-dichloropropane) An electric heater was wrapped around the center 70 cm of a quartz tube with an inner diameter of 25 mm and a length of 110 cm, and the internal temperature was set at 500°C. 1,2-dichloropropane was charged at 350 g/hr from one end of this quartz tube and thermally decomposed inside the tube.
The decomposition products coming out in gas form from the other end are condensed in a condenser cooled with ice water, and the decomposition products are 239g/
Got it in hr. The organic composition of this decomposition product is 59.5% by weight of allyl chloride, 1-chloropropene (cis,
(total of trans) 35.2% by weight, benzene 0.2% by weight, and unreacted 1,2-dichloropropane
It was 1.7% by weight.

Example 1 Phthalic anhydride 148 (1 mol), anhydrous sodium carbonate 116 g (1.1 mol), triethylamine 5 g,
Hydroquinone 0.5g, water 3.0g, stainless steel (SUS304, 3.1 x 2.5 x 0.17cm, 9.1810 as a test piece)
g) into an autoclave with an internal volume of 1, the inside of the autoclave was replaced with nitrogen, and then,
The temperature was raised to 140°C while stirring.

Next, 283 g of the thermal decomposition product of 1,2-dichloropropane obtained in Reference Example 1 (allyl chloride content)
(168.4 g, 2.2 mol) was gradually charged over 4 hours.
Thereafter, the reaction was continued for an additional 2 hours.

The reaction temperature was kept at 140℃, and the reaction pressure was 10Kg/cm ²
Carbon dioxide gas and unreacted chlorpropenes generated as G were gradually removed from the autoclave and discharged to the outside of the system through a dry ice trap. After the reaction was completed, the pressure inside the autoclave was lowered to normal pressure, and the autoclave was cooled to room temperature. The contents were then removed from the autoclave. The contents were a yellowish white sticky liquid, and the produced inorganic matter was filtered, the filtered residue was washed with ether, and the filtrate and ether washings were combined. After washing this ether solution with water to remove water-soluble components, the ether solution was dried over anhydrous sodium sulfate, the ether was removed by vacuum distillation, and 227 g (0.92 mol) of diallyl phthalate was obtained.
I got it.

On the other hand, the weight loss of the stainless steel test piece was 0.0001g, and the degree of corrosion was 0.01mm per year.

Comparative Example 1 The same method as in Example 1 was carried out except that water was not added. After the reaction is complete, the content is a dark green sticky liquid, containing diallyl phthalate.
225 g (0.91 mol) was obtained.

On the other hand, corrosion holes were observed on the surface of the stainless steel specimen, the weight loss was 0.3130g, and the degree of corrosion was 32.9mm per year.

Comparative Example 2 The same method as in Example 1 was carried out except that the amount of water added in Example 1 was 0.60 g. After the reaction was completed, the contents were a yellow-green sticky liquid, and 227 g (0.92 mol) of diallyl phthalate was obtained.

On the other hand, the weight loss of the stainless steel test piece was 0.1040g, and the degree of corrosion was 10.9mm per year.

Comparative Example 3 The same method as in Example 1 was carried out except that the amount of water added was 10.0 g. After the reaction was completed, the contents were a yellowish white sticky liquid, and 172 g (0.70 mol) of diallyl phthalate was obtained.

On the other hand, the weight loss of the stainless steel test piece was 0.0002g, and the degree of corrosion was 0.02mm per year.

Reference example In Comparative Example 1, instead of the thermal decomposition product of 1,2-dichloropropane, 283 g (3.7 mol) of distilled and purified allyl chloride, 249 g (1.68 mol) of phthalic anhydride, and anhydrous sodium carbonate were used. 195
The same method as in Comparative Example 2 was carried out except that the amount of hydroquinone was changed to 1.84 g (1.84 mol), 8.4 g of triethylamine, and 0.84 g of hydroquinone. After the reaction, the contents were a yellow-green sticky liquid, containing 379 g of diallyl phthalate.
(1.54 mol) was obtained.

On the other hand, the weight loss of the stainless steel test piece was 0.0410 g, and the degree of corrosion was 4.3 mm per year.

(Effects of the Invention) According to the method of the present invention, not only can 1,2-dichloropropane, which has not been effectively used in the past, be used industrially advantageously, but also a very small amount of water can be added. Since it is possible to use industrially inexpensive equipment materials by a simple method, it has great industrial utility value.

Claims (1)

[Claims] 1. The decomposition products obtained by decomposing 1,2-dichloropropane, mainly consisting of allyl chloride and chloropropenes, are mixed as alkali metal salts of carboxylic acids, or carboxylic acids and/or carboxylic acid anhydrides and alkali metals. 1. A method for preventing corrosion of a reaction device, which comprises adding 0.3 to 3.0% by weight of water to the decomposed product when producing allyl ester by reacting with a carbonate.