JP3460714B2 - Method for inhibiting thermal decomposition of cycloalkanone oxime - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for suppressing the thermal decomposition of cycloalkanone oxime. [0002] When a cycloalkanone oxime is used at a high temperature, for example, when the cycloalkanone oxime is used after being vaporized, thermal decomposition of the cycloalkanone oxime occurs. For this reason, there is a problem that the cycloalkanone oxime is lost, and furthermore, the thermal decomposition product may be harmful to a chemical operation to be performed subsequently. [0003] As a method for suppressing the thermal decomposition of cycloalkanone oxime, for example, in the vaporization zone of cyclohexanone oxime, at least one metal selected from the group consisting of an alkali metal or an alkaline earth metal itself, and oxides, hydroxides, and alcoholates thereof. Has been proposed (Japanese Patent Publication No. 47-41909). However, this method cannot sufficiently suppress the thermal decomposition of cycloalkanone oxime, and is not a satisfactory method. [0005] In view of such a situation,
The present inventors have conducted various studies on the thermal stability of cycloalkanone oxime and found that thermal decomposition of cycloalkanone oxime can be easily and efficiently suppressed by the presence of a specific compound. Was completed. Namely, the present invention is represented by the following general formula _{(1) NR 1 R 2 R} 3 (1) ( wherein, R _1, R ₂ and R ₃ are also each a hydrogen atom
It represents a lower alkyl group. The compound represented by), shea
0.1 to 200 mol% based on the chloralkanone oxime
An object of the present invention is to provide a method for suppressing thermal decomposition of cycloalkanone oxime, which is characterized in that it is present. Hereinafter, the present invention will be described in detail. The cycloalkanone oxime in the present invention is not particularly limited, for example, cyclopentanone oxime, cyclohexanone oxime, cycloheptanone oxime, cyclooctanone oxime, cyclononanone oxime, cyclodecanone oxime, etc. C5-10 cycloalkanone oxime is mentioned. [0008] As the compound which suppresses pyrolysis one <br/> general formula _{(1) NR 1 R 2 R} 3 (1) ( wherein below, R _1, R ₂ and R ₃ are also each a hydrogen atom
It represents a lower alkyl group. ) Are used . The specific compounds include, for example, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monopropylamine, dipropylamine, tripropylamine, monobutylamine, dibutylamine, tributylamine and the like. 1 to 12 lower alkylamines and ammonia. These may be used alone or as a mixture. The above compound is used in an amount of 0. 1 to cycloalkanone oxime. 1 to 200 mol%. The mode of using the above compound is not particularly limited. For example, it may be mixed with cycloalkanone oxime in advance or introduced from a separate system. In these cases, the cycloalkanone oxime may be used by dissolving it in an organic solvent such as alcohol, benzene or toluene. According to the present invention, when cycloalkanone oxime is used after being vaporized, thermal decomposition can be particularly effectively suppressed. Depending on the type of cycloalkanone oxime, the temperature of the vaporization zone is typically 16 at normal pressure.
It is 0 ° C. or higher, and in the case of reduced pressure, a lower temperature than at normal pressure is also possible. As described above, according to the present invention,
The thermal decomposition of cycloalkanone oxime can be easily and efficiently suppressed by the presence of the above specific compound. Also, this specific compound can be reused by being recovered. Next, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples. EXAMPLE 1 A quartz tube having an inner diameter of 10 mm and a length of 40 cm was inserted into an electric furnace set at 350 ° C., and 6.9 g / methanol solution containing 43.5% by weight of cyclohexanone oxime was inserted into the quartz tube.
Supplied at the rate of hr. At this time, as a carrier gas, a nitrogen gas containing 5% by volume of ammonia was supplied at a rate of 4.2 l / hr to vaporize cyclohexanone oxime.
At this time, the amount of ammonia was about 35 mol% based on cyclohexanone oxime. After continuing this operation for 256 hours, the supply of the cyclohexanone oxime solution was stopped. After cooling in a nitrogen gas atmosphere, the weight of the carbonaceous material attached to the quartz tube wall was measured and found to be 26.6 mg. Comparative Example 1 In place of the nitrogen gas containing 5% by volume of ammonia in Example 1, 4.2 l / nitrogen gas was used as a carrier gas.
Cyclohexanone oxime was vaporized in the same manner as in Example 1 except that hr was used. After cooling in a nitrogen gas atmosphere, the weight of the carbonaceous substance was measured in the same manner as in Example 1 and found to be 225.5 mg. Example 2 1 g of cyclohexanone oxime and 1 drop (0.03 g) of 5.6% by weight ammonia water were added to a stainless steel sealed container having an inner volume of 50 ml and the atmosphere was replaced with nitrogen, and the mixture was placed in an oven set at 180 ° C. Heated for hours. At this time, the amount of ammonia was 1 mol% with respect to cyclohexanone oxime.
Met. After cooling, the residue was measured by gas chromatography to find that the amount of cyclohexanone oxime was 93% by weight based on the charged amount. Comparative Example 2 The procedure of Example 2 was repeated, except that 1 drop (0.03 g) of a 16.7% by weight aqueous solution of potassium hydroxide was added instead of the aqueous ammonia. At this time, the amount of potassium hydroxide was 1 mol% based on cyclohexanone oxime. After cooling, the residue was measured by gas chromatography to find that the amount of cyclohexanone oxime was 85% by weight based on the charged amount. Comparative Example 3 The procedure of Example 2 was repeated, except that no aqueous ammonia was added. After cooling, the residue was measured by gas chromatography to find that the amount of cyclohexanone oxime was 82% by weight based on the charged amount. Example 3 The procedure of Example 2 was repeated, except that one drop (0.03 g) of a 29.8% by weight aqueous solution of triethylamine was added instead of the aqueous ammonia. At this time, the amount of triethylamine was 1 mol% based on cyclohexanone oxime. After cooling, the residue was measured by gas chromatography to find that the amount of cyclohexanone oxime was 92% by weight based on the charged amount.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-193957 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C07C 249/14 C07C 251/44

Claims (1)

(57) [Claims] [Claim 1] NR ₁ R ₂ R ₃ (1) wherein R ₁ , R ₂ and R ₃ are each a hydrogen atom or a lower alkyl group In the amount of 0.1 to 200 mol% based on cycloalkanone oxime.
A method for suppressing the thermal decomposition of cycloalkanone oxime, wherein cycloalkanone oxime is present.
Except during washing with an aqueous solution of ammonium sulfate) .