KR20010044854A - Novel process of purification for crude o-chloro-p-toluidine and process of preparation for o-chloro-p-toluidine-5-sulfonic acid using the purified o-chloro-p-toluidine - Google Patents

Abstract

PURPOSE: Provided are a novel process for refining o-chloro-p-toluidine(OCPT) of low quality to obtain sulfate of the OCPT and a process for producing OCPT-5-sulfonate from the refined sulfate of the OCPT by a solvent-free process or a solvent process. CONSTITUTION: The refining process comprises the steps of: adding 10pts.wt. of the low quality liquid OCPT and 40-55pts.wt. of a C1-C5 alcohol and reacting for 25-35 minutes; adding 5-10pts.wt. of sulfuric acid for 3-5 hours; leaving the resultant alone for 1-3 hours and filtering; cleaning the solid substance, obtained from the filtration, by using alcohol and drying. The solvent-free process for producing the OCPT-5-sulfonate comprises the steps of: adding 10pts.wt. of the OCPT sulfate and 1.3-1.5pts.wt. of water and reacting for 25-35 minutes; adding 1.7-2.1pts.wt. of the sulfuric acid for 1-3 hours; performing a dissolution at 140-160deg.C for 1-3 hours and making a vacuum state; reacting at 165-175deg.C under 600-750mmHg for 2-4 hours; reacting at 195-205deg.C under 600-750mmHg for 14-16 hours; reacting at 165-175deg.C under 600-750mmHg for 3-5 hours; cutting off a heat source until the amount of the non-reacted OCPT becomes less than 0.32wt% and cooling 5-8 hours. The solvent process comprises the steps of: adding 10pts.wt. of the OCPT sulfate and 40-60pts.wt. of 1,2-dichlorobenzene and reacting for 25-35 minutes; adding 1.7-2.1pts.wt. of the sulfuric acid for 2-4 hours; reflux-cooling at 170-190deg.C for 11-13 hours; cooling the resultant to be 40-60deg.C; separating a solvent by using a decanter and filtering and drying.

Description

Novel Purification Method of O-Chloro-J-Toluidine (OCPT) Compound, and Method for Preparation of OCP-5-Sulfonic Acid CHLORO-P-TOLUIDINE-5-SULFONIC ACID USING THE PURIFIED O-CHLORO-P-TOLUIDINE}

The present invention relates to a novel purification method of o-chloro-p-toluidine (OCPT) compound and a method for synthesizing OCPT-5-sulfonic acid using the same, and more particularly, a method for purifying low-grade OCPT in the form of sulfate, and A method for preparing OCPT-5-sulfonic acid from salts.

OCPT-5-sulfonic acid is one of the core raw materials of azo red pigment, and its red color is vivid, so it is widely used as a raw material of red ink, paint and the like. At present, OCPT-5-sulfonic acid is prepared by reacting OCPT with concentrated sulfuric acid. When OCPT-5-sulfonic acid is produced from high-quality OCPT, the purity and yield are excellent, but the price of OCPT, a raw material, is high. There is a disadvantage in that the production cost of phonic acid is increased, on the other hand, in the case of manufacturing OCPT-5-sulfonic acid from low-grade OCPT, the production cost is lowered, while the purity and yield are low. In the art, a method of producing OCPT-5-sulfonic acid by mixing low-grade OCPT and high-grade OCPT in an appropriate ratio of 1: 1, etc. is widely performed, and the purity of OCPT-5-sulfonic acid is also followed according to this method. There is a problem in that it is difficult to obtain excellent quality from the production of OCPT-5-sulfonic acid from high quality OCPT, and the manufacturing cost is also higher than that of low quality OCPT.

The present invention is to solve some of the above problems, the low-grade OCPT is purified by a low cost simple process, high-purity o-chloro-p-toluidine (OCPT) -5-sulfur from the purified OCPT salt By preparing phonic acid, it is intended to provide a method for producing OCPT-5-sulfonic acid of equivalent or better purity than the process for producing OCPT-5-sulfonic acid from high quality OCPT. In addition, to provide a method for producing OCPT-5-sulfonic acid by recycling the by-product filtrate during the purification of OCPT.

The present invention relates to a novel purification method of o-chloro-p-toluidine (OCPT) compound and a method for synthesizing OCPT-5-sulfonic acid using the same.

The first aspect of the present invention comprises the steps of: (i) adding 10 parts by weight of low-grade liquid OCPT (o-chloro-p-toluidine) into the reactor and adding 40-55 parts by weight of C ₁ -C ₅ alcohol to stir for 25 to 35 minutes; (ii) adding 5-10 parts by weight of sulfuric acid to the reactor for 3-5 hours; (iii) filtering the reaction after leaving for 1-3 hours; And (iv) washing and drying the solid material obtained after filtration several times with the alcohol.

Low-grade OCPTs currently available are o-chlorotoluene, p-toluidine, 2-chloro-5-methyl aniline, 2-chloro-4-nitro-toluene, 3-bromo-4, in addition to OCPT (purity: about 96.8%). Impurities such as -methylaniline, 2,5-dichloro-4-methylaniline, 2,6-dichloro-3-methylaniline, 3,5-dichloro-4-methylaniline, and the like.

Of the C ₁ -C ₅ alcohols used as the reaction solvent, isopropyl alcohol (IPA) is particularly preferred because it is relatively inflammable and economical.

It is preferable to add 47-48 parts by weight of the alcohol which is the reaction solvent.

It is preferable to add dropwise sulfuric acid over 4 hours by 7 parts by weight.

The solid obtained after filtration is the sulfate of OCPT, which can be used for the preparation of OCPT-5-sulfonic acid, and the filtrate remaining after filtration can also be recycled for the production of OCPT-5-sulfonic acid.

The second aspect of the present invention comprises the steps of: (i) adding 10 parts by weight of the OCPT salt obtained by the method for purifying OCPT into the reactor, adding 1.3-1.5 parts by weight of water, and then stirring it for 25-35 minutes; (ii) adding 1.7-2.1 parts of sulfuric acid for 1-3 hours; (iii) dissolving at 140-160 ° C. for 1-3 hours and then vacuuming the reactor; (iv) reaction at 165-175 ° C., 600-750 mmHg under reduced pressure for 2-4 hours; (v) reacting at 195-205 ° C. under a reduced pressure of 600-750 mmHg for 14-16 hours; (vi) 165-175 ° C., reaction under reduced pressure of 600-750 mmHg for 3-5 hours; And (vii) blocking the heat source and cooling for 5-8 hours when the unreacted OCPT amount is 0.32% by weight or less.

The above-mentioned method is the so-called 'solvent-free method' among the methods for producing OCPT-5-sulfonic acid from OCPT.

In step (i), it is preferable to add 1.4 parts by weight of water per 10 parts by weight of the OCPT salt and stir for 30 minutes.

In step (ii), it is preferable to add 1.9 parts by weight of sulfuric acid for 2 hours.

In the step (iii), it is preferable to dissolve at 150 ° C. for 2 hours to apply a vacuum to the reactor.

In the above step (iv), the reaction is preferably carried out at 170 ° C. and 650-700 mmHg for 3 hours.

In the step (v), it is preferable to react at 200 ° C. at 650-700 mmHg for 15 hours.

In the above step (vi), it is preferable to react at 170 ° C. at 650-700 mmHg for 4 hours.

In step (vii), the amount of unreacted OCPT is determined by the amount of free amine in the reactor.

The third aspect of the present invention, (i) 10 parts by weight of the OCPT salt obtained by the above-described OCPT purification method into the reactor and 40-60 parts by weight of 1,2-dichlorobenzene (ODCB) and then stirred for 25 to 35 minutes Doing; (ii) adding 1.7-2.1 parts of sulfuric acid for 2-4 hours; (iii) raising the temperature of the reactor to continue reflux cooling at 170-190 ° C. for 11-13 hours; (iv) cooling the reactor to 40-60 ° C .; And (v) transferring the reactants to a holding tank, separating the solvent with a decanter, filtering, and drying the obtained product.

The above method is the so-called 'solvent method' among the methods for producing OCPT-5-sulfonic acid from OCPT.

In step (i), it is preferable to add 50 parts by weight of ODCB per 10 parts by weight of the OCPT salt and stir for 30 minutes.

In the step (ii), 1.9 parts by weight of sulfuric acid is preferably added dropwise for 3 hours.

In the step (iii), it is preferable to react for 12 hours at 180-182 ℃.

In step (iv) above, it is preferred to cool the reactor temperature to about 50 ° C.

A fourth aspect of the present invention includes the steps of: (i) recovering the by-product filtrate upon purification of the OCPT and transporting it to a treatment tank; (ii) treating 10 parts by weight of the filtrate with 0.2-0.4 parts by weight of activated carbon and then transferring it to the reactor; (iii) adding 0.6-0.8 parts by weight of OCPT in response to excess sulfuric acid in the reactor; (iv) raising the reactor temperature to 100-130 ° C. to distill the alcohol used in OCPT purification to recover the alcohol; (v) adding 7-9 parts by weight of OCDB to the reactor, maintaining the temperature at 115-125 ° C. to further distill and recover the alcohol, and further adding 10-14 parts by weight of OCDB and stirring for 25-35 minutes; (vi) raising the temperature of the reactor to continue reflux cooling at 170-190 ° C. for 11-13 hours; (vii) cooling the reactor to 40-60 ° C .; And (viii) transferring the reactants to a holding tank, separating the solvent with a decanter, filtering, and drying the obtained product.

The present invention is economically advantageous in that the by-product filtrate is also recycled in the production of OCPT-5-sulfonic acid by regeneration of low-grade OCPT.

In step (ii), it is preferable to use 0.3 parts by weight of activated carbon per 10 parts by weight of the filtrate.

In the step (iii), it is preferable to add 0.7 parts by weight of OCPT.

In step (iv), the reactor temperature is preferably 120 ° C.

In the step (v), OCDB is initially added 8 parts by weight to recover the alcohol, then 12 parts by weight is preferably added to recover the alcohol.

In the above step (vi), it is preferable to react at 180-182 ° C. for 12 hours, and then cool to 50 ° C.

The invention is illustrated in more detail by the following examples which do not limit the scope of protection of the present invention.

Example 1 Purification of OCPT

Example 1-1

200 g (1.367 mol) of crude Chinese OCPT containing 96.8% by weight of OCPT was added to a three-necked flask (2 L) reactor, 1200 ml of IPA was added thereto, followed by stirring for 30 minutes, followed by 138.25 g (1.367 mol) of 97% sulfuric acid for 4 hours. Was dropped into the dropping apparatus and left for 2 hours. Thereafter, the reaction product was filtered, and the filtered reaction product was washed twice with 150 ml of IPA, followed by drying to obtain 235.94 g (yield = 80.92 wt%) of OCPT sulfate having a purity of 99.58%.

Example 1-2

The same process as in Example 1-1 was carried out except that ethyl alcohol was used instead of IPA, to obtain 209.94 g (yield = 72.00 wt%) of OCPT sulfate having a purity of 99.59%.

Example 1-3

The same process as in Example 1-1 was carried out except that 800 ml of IPA was used, to obtain 211.51 g of OCPT sulfate having a purity of 99.52% (yield = 72.54 wt%).

Example 1-4

The same process as in Example 1-1 was carried out except that 69.13 g (0.68 mol) of sulfuric acid was used to obtain 247.65 g (yield = 84.94% by weight) of OCPT sulfate having a purity of 99.41%.

Example 2 Preparation of OCPT-5-Sulfonic Acid from the OCPT Sulfate by Solventless Method

235.94 g of the OCPT salt prepared in Example 1-1 and 32 g of water were added to a four-necked flask (1 L) reactor, followed by stirring for 30 minutes, and 44.82 g of sulfuric acid was added dropwise thereto over 2 hours, and the temperature was increased to 150 ° C. After the vacuum was put into the reactor. The temperature was then raised to 170 ° C. again and maintained at 650-700 mmHg for 3 hours. Then, the mixture was heated up again and reacted at 200 ° C. and 650-700 mmHg for 15 hours. At the same pressure, the reaction temperature was lowered to 170 ° C. and continued for 4 hours. Then, when the unreacted OCPT content in the reactor is 0.32% by weight or less, the heat source is blocked and cooled for 6 hours to give 249.18 g of OCPT-5-sulfonic acid, which is 98.4% pure and pale pinkish white crystals (yield) = 80.92 wt%).

Example 3 Preparation of OCPT-5-Sulfonic Acid from Solvent Method from OCPT Sulfate

200 g (1.367 mol) of OCPT salt prepared in Example 1-1 and 500 ml of 1,2-dichlorobenzene (ODCB) were added to a three-necked flask reactor (1 L), followed by stirring for 30 minutes, followed by 10.71 g of sulfuric acid for 3 hours. It was dripped by the dropping apparatus. Thereafter, the temperature of the reactor was raised to 180 ° C. and reflux was continued for 12 hours. The reactor was then cooled to 50 ° C. and the reaction product was filtered and dried to give 249.18 g of OCPT-5-sulfonic acid with a purity of 98.4% (gray yield) (yield = 80.92% by weight).

<Example 4: Preparation of OCPT-5-sulfonic acid by solvent method from filtrate by-produced during OCPT purification>

In Example 1-1, 445 ml of the filtrate formed after filtration were treated with 14 g of activated carbon, and the filtrate was transferred to a three-necked flask reactor (1 L). In addition, 21.44 g of OCPT was added to the reactor to correspond to excess sulfuric acid (100 wt%, 14.85 g), and the reactor temperature was raised to about 90 ° C. to recover about 200 ml of IPA. Subsequently, 200 ml of 1,2-dichlorobenzene (ODCB) was added and maintained at 90 ° C. to further recover 240 ml of IPA. Thereafter, 300 ml of ODCB was further added, the temperature of the reactor was raised to 180 ° C., and reflux was continued for 12 hours. Thereafter, the reactor was cooled to 50 DEG C while stirring, and the reaction product was filtered and dried to obtain 53.98 g of OCPT-5-sulfonic acid in gray powder having a purity of 98.1%.

Comparative Example 1: Production of OCPT-5-Sulfonic Acid by Solvent Method from Low-grade OCPT

30 g (0.206 ml) of low-grade OCPT and 600 ml of 1,2-dichlorobenzene (ODCB) were added to a four-necked flask reactor (1 L), and the reactor was stirred for 10 minutes. And 21.4 g (0.217 mol) of 97% sulfuric acid was dripped over 20 minutes. Thereafter, the temperature was raised to reflux cooling at 180 ° C. for 12 hours. Thereafter, the mixture was cooled to 50 ° C., filtered, and dried at 140 ° C. for 12 hours to obtain 44.8 g (yield = 98.3 wt%) of OCPT-5-sulfonic acid on gray powder having a purity of 96.8%.

<Comparative Example 2: Production of OCPT-5-Sulfonic Acid from High Purity OCPT (Solvent Method)>

Into a four-necked flask reactor (1 L), 30 g (0.206 ml) of commercially available German OCPT containing 99.77% of OCPT and 600 ml of 1,2-dichlorobenzene (ODCB) were charged and the reactor was stirred for 10 minutes. And 21.4 g (0.217 mol) of 97% sulfuric acid was dripped over 20 minutes. Thereafter, the temperature was raised to reflux cooling at 180 ° C. for 12 hours. Then, the mixture was cooled to 50 ° C., filtered, and dried at 140 ° C. for 12 hours to obtain 44.8 g (98.3% by weight) of OCPT-5-sulfonic acid having a purity of 98.0%.

Comparing the results of Comparative Example 1 with the results of Example 3, in the method for preparing OCPT-5-sulfonic acid after purifying crude OCPT of low quality according to the present method, the purity of the product, OCPT-5-sulfonic acid, was 98.1. %, And according to the conventional method for preparing OCPT-5-sulfonic acid directly from low-quality crude OCPT, the purity of OCPT-5-sulfonic acid is 96.8%, and thus OCPT-5 from OCPT purified and purified OCPT according to the present method. It can be seen that the method for preparing sulfonic acid is superior to the prior art in terms of purity of OCPT-5-sulfonic acid.

Also, comparing the results of Comparative Example 2 with the results of Examples 2 and 3, the purity of OCPT-5-sulfonic acid obtained by preparing OCPT-5-sulfonic acid after purifying it from crude OCPT of low quality according to the present method (98.1 and 98.4%) can be seen to be comparable or better than the purity (98.0%) of OCPT-5-sulfonic acid obtained by preparing OCPT-5-sulfonic acid from high purity OCPT.

Claims (9)

(i) adding 10 parts by weight of low-grade liquid OCPT (o-chloro-p-toluidine) to 40-55 parts by weight of C ₁ -C ₅ alcohol and stirring it for 25-35 minutes; (ii) adding 5-10 parts by weight of sulfuric acid to the reactor for 3-5 hours; (iii) filtering the reaction product after standing for 1-3 hours; And (iv) a method for purifying OCPT comprising washing and drying the solid material obtained after filtration several times with the alcohol. The method of claim 1, wherein the alcohol is isopropyl alcohol (IPA). The method of claim 1, wherein in step (ii), 7 parts by weight of sulfuric acid is added for 4 hours. (i) adding 10 parts by weight of the OCPT salt obtained by the method according to claim 1 into the reactor, adding 1.3 to 1.5 parts by weight of water and stirring for 25 to 35 minutes; (ii) adding 1.7-2.1 parts of sulfuric acid for 1-3 hours; (iii) dissolving at 140-160 ° C. for 1-3 hours and then vacuuming the reactor; (iv) reaction at 165-175 ° C., 600-750 mmHg under reduced pressure for 2-4 hours; (v) reacting at 195-205 ° C. under a reduced pressure of 600-750 mmHg for 14-16 hours; (vi) 165-175 ° C., reaction under reduced pressure of 600-750 mmHg for 3-5 hours; And (vii) a method of producing OCPT-5-sulfonic acid comprising the step of shutting off the heat source and cooling for 5-8 hours when the amount of unreacted OCPT is 0.32% by weight or less. The process according to claim 4, wherein the reaction is carried out in step (iv) at 170 ° C., 650-700 mmHg for 3 hours. The process according to claim 5, wherein the reaction is carried out in step (v) at 200 ° C., 650-700 mmHg for 15 hours. The process according to claim 6, wherein the reaction is carried out in step (vi) at 170 ° C., 650-700 mmHg for 4 hours. (i) adding 10 parts by weight of the OCPT salt obtained by the method according to claim 1 into the reactor, 40-60 parts by weight of 1,2-dichlorobenzene (ODCB) and then stirring for 25-35 minutes; (ii) adding 1.7-2.1 parts of sulfuric acid for 2-4 hours; (iii) raising the temperature of the reactor to continue reflux cooling at 170-190 ° C. for 11-13 hours; (iv) cooling the reactor to 40-60 ° C .; And (v) transporting the reactants to a holding tank, separating the solvent with a decanter, filtering and drying the product obtained. (i) recovering the by-product filtrate in the filtration step of the method according to claim 1 and transferring it to a treatment tank; (ii) treating 10 parts by weight of the filtrate with 0.2-0.4 parts by weight of activated carbon and then transferring it to the reactor; (iii) adding 0.6-0.8 parts by weight of OCPT to correspond to the excess sulfuric acid in the reactor; (iv) raising the reactor temperature to 100-130 ° C. to distill the alcohol used in OCPT purification to recover the alcohol; (v) adding 7-9 parts by weight of OCDB to the reactor, maintaining the temperature at 115-125 ° C. to further distill and recover the alcohol, and further adding 10-14 parts by weight of OCDB and stirring for 25-35 minutes; (vi) raising the temperature of the reactor to continue reflux cooling at 170-190 ° C. for 11-13 hours; (vii) cooling the reactor to 40-60 ° C .; And (viii) transferring the reactants to a holding tank, separating the solvent with a decanter, filtering, and drying the obtained product.