JPS6360022B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing 2-methylquinoline. 2-Methylquinoline is included in the bases separated from coal tar and is used as a raw material for quinophthalone dyes and pigments. However, 2-methylquinoline has a boiling point close to that of quinoline, isoquinoline, 8-methylquinoline, etc., and it is extremely difficult to obtain highly pure 2-methylquinoline by distillation alone. On the other hand, quinoline, isoquinoline, 2-methylquinoline, and 8-methylquinoline all form adducts with urea, but 2-methylquinoline in particular forms adducts much more easily than other bases. Utilizing this property, it is possible to selectively separate 2-methylquinoline as a urea adduct from a mixture of quinoline, isoquinoline, 2-methylquinoline, and 8-methylquinoline, and the resulting 2-methylquinoline urea After purifying the adduct,
High purity 2-methylquinoline is obtained by decomposition. A method for decomposing 2-methylquinoline urea adduct is to add acid or alkali and heat it to decompose urea into ammonia and carbon dioxide gas, thereby liberating 2-methylquinoline. It would be advantageous if 2-methylquinoline could be obtained only by heating without decomposing urea, since there are problems such as the inability to process urea and severe corrosion of the equipment. However, according to the findings of the present inventors, when a solid 2-methylquinoline urea adduct is heated as it is, it does not decompose into 2-methylquinoline and urea, but decomposition of urea occurs from around 130°C and gradually The whole is carbonized and 2-methylquinoline cannot be obtained. As a result of various studies on decomposition methods for 2-methylquinoline urea adducts, we found that when heated in the presence of water and a solvent that dissolves 2-methylquinoline but does not substantially dissolve it in water, the adduct decomposes into 2-methylquinoline. 2-methylquinoline is dissolved in the solvent and urea is dissolved in the water, so if this is separated into a solvent layer and a water layer without cooling,
It has been found that 2-methylquinoline can be recovered from the solvent layer by known methods such as distillation and extraction, and that the aqueous layer can be recycled as a raw material for forming adducts. Furthermore, in this case, when the adduct in powder form is heated in the presence of water and a solvent, the adduct gradually softens and fuses, and the entire adduct becomes a lump, and decomposition occurs only from the surface. Although it takes a long time to complete the decomposition, we have found that using an aqueous surfactant solution can easily decompose the adduct in a short time without causing such problems. The present invention was made based on this knowledge, and by thermally decomposing a 2-methylquinoline urea adduct in the presence of an aqueous surfactant solution,
-This is a method for obtaining methylquinoline. The 2-methylquinoline urea adduct is, for example, 2
- It can be obtained by adding finely powdered urea or a 10-50% aqueous urea solution to a mixture containing methylquinoline or 2-methylquinoline and stirring the mixture. As a mixture containing 2-methylquinoline, a mixture obtained by dividing the base separated from coal tar into appropriate fractions is suitable, and a mixture containing mainly a fraction having a boiling point of 240 to 250°C is particularly suitable. At this time, if the concentration of 2-methylquinoline in the mixture is high, the resulting adducts will increase the viscosity of the entire slurry, making stirring impossible.
It is necessary to add a diluent to reduce the viscosity. As a diluent, it has a great effect on reducing slurry viscosity.
Toluene is effective in forming adducts that are easy to filter.
Xylene and methyl isobutyl ketone are preferred. The produced urea adduct can be separated from the mixture by filtration. The adduct separated from unreacted products by filtration is 2
- Purified to meet the required purity of methylquinoline. Since the adduct is difficult to dissolve in most solvents, it is purified by washing. The adduct thus obtained is decomposed by heating and stirring in the presence of an aqueous solution of a surfactant and a solvent that dissolves 2-methylquinoline but is substantially insoluble in water. The surfactant used is one that has good dispersibility of the adduct, does not cause fusion due to heating, and is capable of phase separation between the 2-methylquinoline solution and the urea aqueous solution generated by heating. There needs to be. Examples of such substances include polyoxyethylene nonylphenol ether, polyoxyethylene octylphenol ether, polyoxyethylene monolaurate, polyoxyethylene monostearate, and polyoxyethylene monooleate, which have a polyoxyethylene group and have an HLB of 13 There are 14 nonionic surfactants, and these surfactants are used by being dissolved in water to a concentration of 0.01 to 0.5%, for example. Cases in which phase separation is not performed are outside the scope of the present invention, but if phase separation is somewhat insufficient, separation can be completed by means such as heating or centrifugation. In addition, as the surfactant concentration increases, the phase separation property decreases but the decomposition time becomes shorter, and as the concentration decreases, the phase separation property improves and the decomposition time tends to become longer. Therefore, determine the concentration depending on the type of surfactant. The amount of water relative to the adduct needs to be 1 part by weight or more per 1 part by weight of the adduct; if it is less than this, the decomposition of the adduct will be slow. On the other hand, when the amount of water added is increased, the concentration of the urea aqueous solution produced decreases, making it difficult to recycle. The preferred amount of water added is 1 to 3 parts by weight per 1 part by weight of the adduct. A thermal decomposition temperature of around 90°C is sufficient. Various solvents such as hydrocarbons, esters, ketones, and ethers can be used as solvents that dissolve 2-methylquinoline but do not mix with water.
In consideration of use in combination with the adduct production step, separation from 2-methylquinoline, etc., alkylbenzenes and ketones are particularly preferred, particularly toluene, xylene, and methyl isobutyl ketone. The amount of these solvents to be used for the adduct is preferably 0.2 parts by weight or more per 1 part by weight of the adduct, and if the amount is less than this, the decomposition of the adduct will be slow. On the other hand, if a large amount of solvent is added, the load on the 2-methylquinoline recovery step will increase, so the amount of solvent added is preferably 0.25 to 1 part by weight per 1 part by weight of the adduct. As mentioned above, when the adduct, the surfactant aqueous solution, and the solvent are mixed and heated to 90 to 80° C. while stirring, the adduct quickly decomposes without being fused.
2-Methylquinoline can be recovered from the solvent layer by a method such as distillation or extraction after stopping the stirring and separating the solvent layer and the aqueous layer. The aqueous layer can be recycled to the adduct production step with the urea concentration adjusted. Although the aqueous layer contains a small amount of surfactant, it does not have any adverse effect on the formation of adducts. Example 1 and comparative examples Quinoline 7.2%, isoquinoline 45.2%, 2-methylquinoline 36.5%, 8-methylquinoline 5.6%,
150 parts by weight of xylene as a diluent was added to 100 parts by weight of a mixture containing 2-methylquinoline having a composition of 5.5%, and to this was added 218 parts by weight of a 14% concentration urea aqueous solution (urea/2-methylquinoline mol). Ratio 2), stirred at 20°C for 2 hours, separated the generated adduct, and washed once with xylene.
72 parts by weight of the adduct was obtained and used to study the decomposition conditions. The purity of 2-methylquinoline obtained by decomposition is 90-91%. Take 10g of this adduct, add 10g of xylene and 30g of an aqueous surfactant solution, and heat it to 80°C while stirring to check the time taken to complete decomposition and the state of separation between the solvent layer and water layer after decomposition. Ta.

[Table] ○ Good separation △ Micro emulsification × Unable to separate ☆ is a comparative example.
Also, take 10 g of this adduct and add 30 g of a surfactant aqueous solution (polyoxyethylene nonyl phenol ether 0.1%) or water without adding a solvent.
30g was added and heated to 80°C while stirring, and the time until completion of decomposition was measured. No decomposition of the adduct occurred in either case when an aqueous surfactant solution was added or when water was added. Example 2 Quinoline 5.3%, isoquinoline 43.5%, 2-methylquinoline 35.5%, 8-methylquinoline 7.7%
To 100 parts by weight of a mixture containing Washing with isobutyl ketone gave 104 parts by weight of the adduct. To 100 parts by weight of this adduct, 20 parts by weight of methyl isobutyl ketone and 100 parts by weight of a 0.1 aqueous solution of polyoxyethylene nonyl phenol ether were added,
The mixture was decomposed by stirring for 30 minutes at °C, after which the oil layer was separated at that temperature and the methyl isobutyl ketone was removed by distillation. The purity of the obtained 2-methylquinoline was 91%, and the recovery rate was 93%.

Claims (1)

[Claims] 1. A 2-methylquinoline urea adduct is thermally decomposed in the presence of an aqueous surfactant solution and a solvent that dissolves 2-methylquinoline but does not substantially dissolve it in water, resulting in phase separation. A method for producing 2-methylquinoline. 2. The manufacturing method according to claim 1, which uses an aqueous surfactant solution having a concentration of 0.01 to 0.40%. 3 the surfactant has a polyoxyethylene group,
The manufacturing method according to claim 1 or 2, wherein the nonionic surfactant has an HLB of 13 to 14. 4. The manufacturing method according to claim 1, wherein the solvent is alkylbenzene or methyl isopropyl ketone.