JPS5859970A - Production of 2,2,4-trimethyl-1,2-dihydroquinoline - Google Patents

Abstract

PURPOSE:Polyfluorinated sulfonic acid resin is used as a catalyst to effect the reaction between aniline and acetone to produce the titled compound with increased yield, reduced residual amount of by-products, which is used as an antioxidant. CONSTITUTION:The reaction of aniline with acetone or diacetone alcohol or mesityl oxide is conducted in the presence of a polyfluorinated sulfonic acid resin catalyst to give 2,2,4-trimethyl-1,2-dihydroquinoline. As the polyfluorinated sulfonic acid resin, is preferably used a product by Dupont C. in USA, named Nafion H and the amount is 1-100g per mole of aniline.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides the following features: , 2,4-) It relates to a method for producing dimethyl-1,2-dihydroquinoline.

2.2.4-) Dimethyl-1,2-dihydroquinoline is a compound useful as an anti-aging agent for polymeric materials, which is usually treated in the presence of an acidic catalyst such as hydrochloric acid or iodine.
It is known that aniline is produced by a dehydration condensation reaction by reacting acetone, diacetone alcohol, or mesityl oxide in a heated layer, but when the reaction is carried out under the above acidic catalyst, 2,2.4-1-' J Methyl-1.2
-It is known that in addition to the dihydroquinoline monomer (hereinafter referred to as monomer), its polymerization product (hereinafter referred to as polymer) and other impurities are produced as various by-products.

For example, while keeping aniline containing hydrochloric acid as a catalyst at a molar ratio of O and OS to aniline at 100°C,
There are two known methods: one in which acetone is allowed to act on the aniline for a period of time, and another method in which aniline containing hydrochloric acid at a molar ratio of 1/7.5 to aniline is kept at 180 to 140°C and acetone is made to act on it for 6 hours. However, in the former method, only about 2,896 particles and about 18% of the residual liquid are obtained, and most of the charged aniline remains unreacted, while in the latter method, residues such as polymers are obtained. About 64%, the monomer is obtained with a yield of only 19%.

For these reasons, the present inventors conducted research on the rapid production of 2,2,4-trimethyl-1,2-dihydroquinoline, and first discovered a method using P-toluenesulfonic acid as a catalyst (Special 1j ＠5＄-115587%), but even with the CCO method, about 19% of the residue was produced as a by-product, and the desired monomer yield was about 60%.

Subsequently, the present inventors conducted further studies to develop a better method for producing monomers, and found that by using a polyfluorinated sulfonic acid resin as a catalyst, the yield of monomers was improved compared to those using these methods. The inventors have discovered that the amount of residue is also reduced, leading to the present invention.

That is, the present invention provides a method for producing 2,2,4-trimethyl-1,2-dihydroquinoline (monomer) by reacting aniline with acetone (or diacetone alcohol or mesityl oxide), in which a polyfluorinated This is an improved method for producing monomers that uses a sulfonic acid resin as a catalyst to improve the monomer yield and reduce the amount of by-product residue.

The amount of polyfluorinated sulfonic acid resin used as a catalyst in the present invention (a typical example is Nafion H manufactured by DuPont in the United States) is not particularly limited, but
From the viewpoint of reaction rate, economy, etc., it is preferably about 1 to 1,001 moles of aniline.

Regarding other reaction conditions, conventionally known methods can be applied mutatis mutandis, and there are no particular restrictions.

Next, the present invention will be explained by examples.

Example 1 5 Q Omj! equipped with acetone introduction device, thermometer, stirrer and condenser. Aniline 12 in 4 flasks
1P (1.8 mol), polyfluorinated sulfonic acid resin 57
．． 2F (equivalent to 0.052 mol based on the molecular weight of 1100 per sulfonic acid group) is charged and heated.

756 tons of acetone is introduced over 8 hours while maintaining the internal temperature at 95-too'c. The distilled unreacted acetone contains water produced by the dehydration reaction, so it is recovered by rectification and used for the next reaction. After the acetone introduction device, the contents of the flask are passed through a glass filter to separate the polyfluorinated sulfonic acid resin. Transfer the F solution into the 14th 500 m flask again and gradually reduce the pressure while keeping the internal temperature at 140-146°C to recover unreacted aniline. 2ip of aniline was recovered at a vacuum level of 10 or higher. . After that, the internal temperature was raised to 190℃, and the degree of vacuum was reduced to 8.
Monomer with a purity of 96% in m Hg t 158.
il was obtained, and 12.2 t of residue was produced as a by-product.

The yield of monomer when converted to purity is 147.8? The yield is 65.6%. In addition, residual liquid 12 produced as a by-product
．． 2F corresponds to 6.4% of the charged aniline.

Example 2 Polyfluorinated sulfonic acid resin was used at 28.6F, the reaction temperature was 105-110℃, and the introduction time of acetone was 1
The dehydration condensation reaction and post-treatment were carried out in the same manner as in Example 1, except that the reaction time was 2 hours, and a monomer of 14111 (purity 95%) and a residue of 15.6F were obtained.

Yield of monomer based on aniline: 4! 6 L, 6%,
The residue is 6.9%.

Comparative Example 1 In the method of Example 1, polyfluorinated sulfonic acid II
I Instead of fat, paratoluenesulfone II - water jJ [
12,4F (0.065 as para-toluenesulfonic acid
The dehydration condensation reaction was carried out in exactly the same manner except that 1 mol) was used. After one reaction was completed, the reaction product was diluted with 100 mol of toluene, kept at 75-85°C, and neutralized with NaOH2, 6F and 60 mol of water. After standing still, separate the layers and remove the aqueous layer. The oil layer is washed several times with 100 ml of water. When the solution became neutral, the oil layer was separated, toluene was removed by distillation, and 4ζ post-treatment was performed in the same manner as in Example 1.
A monomer of 42.4f (purity 97%) and a residue of 42.1y- were obtained. The yield of monomer based on aniline was 61.8%, and the residue was 18.7mm.

Claims (1)

[Claims] When reacting aniline with acetone (or diacetone alcohol or mesityl oxide), a lithium-hydrogenated sulfone is used as a catalyst.