JPH01261359A - Production of p-toluenesulfonic acid and sodium toluenesulfonate - Google Patents

Abstract

PURPOSE:To obtain sodium toluenesulfonate, by adding water to a reaction solution of excess toluene with sulfuric acid, obtaining p-toluenesulfonic acid as monohydrate crystals, simultaneously separating crystals and neutralizing the resultant filtrate, etc., with caustic soda. CONSTITUTION:Toluene is reacted with 80-98% sulfuric acid at 2-4 molar ratio at the boiling point of the toluene and the resultant reaction solution is cooled to about 60 deg.C. Water in an amount corresponding to <=0.75mol based on 1 mol p-toluenesulfonic acid in the reaction solution is then added to crystallize monohydrate crystals of p-toluenesulfonic acid while cooling the reaction mixture to 20-60 deg.C. The above-mentioned crystals are subsequently separated to provide a filtrate. The obtained filtrate, a mixture thereof with part of the above-mentioned reaction solution or mixture of toluenesulfonic acid crystals separated and collected by adding water to the filtrate with the afore-mentioned reaction solution is neutralized with caustic soda to afford sodium toluenesulfonate. The aimed substance of high p-isomer purity is obtained by the above-mentioned method.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] This invention relates to a method for co-producing p-toluenesulfonic acid and sodium toluenesulfonate.

[Conventional technology]

Both p-toluenesulfonic acid and sodium toluenesulfonate are used as various catalysts such as esterification reaction catalysts, polyester polymerization catalysts, curing catalysts for furan resins, phenol resins, etc., and as anti-caking agents for detergents. It is widely used as a solubilizer for various substances and as a viscosity reducing agent for colloids.

p-Toluenesulfonic acid used for these purposes is -
For boat fishing, toluene is sulfonated with a sulfonating agent such as sulfuric acid, fuming sulfuric acid, or sulfuric anhydride, and water is added to the resulting reaction solution to selectively crystallize p-toluenesulfonic acid hydrate crystals. Sodium toluenesulfonate is produced by neutralizing the above-mentioned sulfonation reaction solution with an alkali.

Toluenesulfonic acid and sodium toluenesulfonate obtained by the sulfonation reaction can be converted to p depending on two reaction conditions.
In addition to -toluenesulfonic acid and p-) sodium sulfonate (hereinafter, in some cases, these are abbreviated as two bodies), 0-toluenesulfonic acid and o-) sodium sulfonate (hereinafter, in some cases, these are abbreviated as 2 bodies). It contains 2m-toluenesulfonic acid and sodium m-toluenesulfonic acid (hereinafter referred to as m-form) in various proportions, and also contains by-products such as sulfone. ing.

In addition, in the method for producing p-toluenesulfonic acid, theoretically, toluene and the sulfonating agent may be reacted in stoichiometric amounts.

In practice, a method is used in which a sulfonating agent is used in excess of the stoichiometric amount to toluene (for example, as disclosed in Japanese Patent Application Laid-Open No.
2-139042) and a method of reacting using toluene in excess of the stoichiometric amount with respect to the sulfonating agent (No. 2-139042).
For example, Japanese Patent Application Publication No. 54-98736 and British Patent No. 9678
No. 74, etc.) have been adopted.

[Problems to be Solved by the Invention] p-) In order to produce toluenesulfonic acid and sodium toluenesulfonate according to demand, the reaction solution obtained by the reaction between toluene and the sulfonating agent described above is added to the side each time. There are problems with the complexity of having to process and produce the product and the waste in the process.

In addition, p-1-toluenesulfonic acid is generally required to be a monohydrate crystal with a p-isomer purity of 99% or more, and in addition to meeting this requirement, p-toluenesulfonic acid and toluenesulfonic acid There is a strong need for a method to co-produce soda in a rational manner.

[Means to solve the problem]

The inventors of this invention worked on the above-mentioned co-production method from the viewpoint of ridges, and as a result of intensive study, they were able to complete this invention.

That is, in the present invention, water is added to part or all of a reaction solution containing toluene sulfonic acid obtained by reacting toluene and sulfuric acid in an excess of toluene.

A filtrate obtained by crystallizing p-)luenesulfonic acid as monohydrate crystals from the reaction solution and separating the crystals;
A mixture of the filtrate and the reaction solution, or a mixture of toluenesulfonic acid crystals separated by adding water to the filtrate and the reaction solution is neutralized with caustic soda to obtain sodium toluenesulfonate. It is something to do.

Toluene, one of the raw materials in the method of this invention, is
-Toluene produced from petroleum refining, which is commercially available for boat fishing, is used, and the other raw material, sulfuric acid, is produced using the normal production method 2.
For example, sulfuric acid produced by a sulfur oxidation method and a sulfide ore combustion method can be used.

The preferred concentration of sulfuric acid used is 50 to 100% (weight %; the same applies hereinafter), more preferably 80 to 98%.

If this sulfuric acid concentration is lower than 50%, the sulfonation reaction will be slow (
Therefore, a larger reactor is required.

Furthermore, in the sulfonation reaction, a large amount of heat is required to azeotrope the produced water and the water from the raw material sulfuric acid with toluene, which is economically undesirable.

Sulfuric acid with a concentration exceeding 100% is undesirable because it becomes so-called fuming sulfuric acid and ditolyl sulfone is produced as a by-product during the sulfonation reaction.

The ratio of toluene and sulfuric acid used in the sulfonation reaction of this invention is an excess of toluene, and the preferred molar ratio of toluene and sulfuric acid is 1.5 to 5. More preferably, it is 2-4.

If the molar ratio is lower than 1.5, it becomes difficult to control the temperature as the two reactions progress, and the by-product of ditolylsulfone and the m-form of toluenesulfonic acid tend to increase.
If the molar ratio is higher than 5, it is not preferable because it causes an increase in the amount of heat required for heating, an increase in the reactor volume per unit production amount, and an increase in the size of accompanying equipment such as pumps.

The temperature of the sulfonation reaction is the boiling point of toluene, and the water produced by the reaction with the water in the raw sulfuric acid is removed from the reactor azeotropically with the toluene. After the water is separated into liquid and liquid, the distilled toluene is reacted. Operate to return it to the container.

The completion of the reaction is determined by the distilled water.

This distilled water can be measured almost quantitatively.
When the reaction was completed, water was not substantially contained in the reaction solution 2, and sulfuric acid had reacted almost quantitatively, and no sulfuric acid was present in the reaction solution 1, and the produced toluenesulfonic acid was used in excess. It becomes dissolved in toluene.

This reaction solution was divided based on the desired p-)luenesulfonic acid hydrate, the amount of sodium toluenesulfonate, and the respective composition ratios of O-isomer/m-isomer/p-isomer in the sodium toluenesulfonate. One of the nine divided reaction solutions is supplied to the step of crystallizing p-)toluenesulfonic acid hydrate.

In this step, the crystallization of p-toluenesulfonic acid hydrate is performed by cooling the temperature of the reaction solution to a temperature within the range from the temperature of the sulfonation reaction to preferably 30°C, more preferably 60°C as the lower limit. After.

The reaction is carried out by adding water to the reaction solution, and the water is added in a molar amount smaller than the molar amount of p-toluenesulfonic acid produced in the reaction solution.

If the temperature of the reaction solution when adding water is lower than 30°C, crystals will precipitate rapidly and the p-isomer purity in the crystals will decrease, so it is difficult to maintain the reaction solution within the above temperature range. desirable.

The amount of water to be added is 0.8 mol or less, more preferably 0.0 to 1 mol of p-)luenesulfonic acid in the reaction solution used.
．． If the amount of water is 75 mol or less, and the amount of water is more than 0.8 mol, the proportion of p-isomer in the precipitated toluenesulfonic acid may decrease, which is not preferable.

After the addition of water, the temperature of the reaction solution rises due to the heat of hydration of p-1-luenesulfonic acid, but this is cooled down to a temperature of 20~20°C.
Separate the crystals at a temperature of 60°C.

When this temperature is below 20°C, both the p-form and the O-form m
Also, separation at a temperature higher than 60° C. yields crystals with high p-isomer purity, but the amount thereof is small, which is not preferable.

The thus obtained p-)luenesulfonic acid hydrate crystals are
By removing toluene adhering to the crystals, the desired high-purity p-)luenesulfonic acid can be obtained in the form of monohydrate crystals.

This crystal separation can be performed by conventional separation methods such as centrifugation and filtration.

The toluene-adhered crystals obtained in this separation can be dried by a normal drying method, such as vacuum drying and ventilation drying, to obtain the desired high-purity p-toluenesulfonic acid hydrate crystals. .

The p-)luenesulfonic acid hydrate crystals thus obtained are highly hygroscopic, and therefore must be stored and packed with sufficient care to prevent moisture absorption.

On the other hand, sodium toluenesulfonate has a primary Φ~■ depending on the desired p-body purity in sodium toluenesulfonate.
It can be obtained in this way.

(2) The filtrate from which the p-)toluenesulfonic acid hydrate crystals were separated is directly neutralized with caustic soda to obtain toluenesulfonic acid sorta.

(2) The filtrate from which the p-)toluenesulfonic acid hydrate crystals were separated is mixed with the remaining reaction solution previously divided, and this mixture is neutralized with caustic soda to obtain sodium toluenesulfonate.

(2) Water is further added to the filtrate from which the p-toluenesulfonic acid hydrate crystals have been separated, and the p-)toluenesulfonic acid hydrate crystals are crystallized by an operation similar to the separation method. Obtain toluenesulfonic acid crystals containing p-isomer at a higher concentration than the p-isomer in the toluenesulfonic acid isomers contained in the separated filtrate, mix the crystals with the remaining reaction solution after the division, and The mixture is neutralized with caustic soda to obtain sodium toluenesulfonate.

In addition, in the method (2) above, there is no need to divide the reaction solution, and the entire amount is supplied to the crystallization step of p-)toluenesulfonic acid hydrate crystals to separate p-toluenesulfonic acid and sodium toluenesulfonate. It is possible to co-produce products with

When neutralizing by these methods, the caustic soda aqueous solution used may be a caustic soda aqueous solution whose concentration has been adjusted in advance so that the sodium toluene sulfonate produced after the neutralization reaction is dissolved, or a caustic soda aqueous solution with a high concentration. The neutralization reaction may be carried out by separately supplying water.

At this time, it is more preferable to supply water first because this prevents crystal precipitation of sodium toluenesulfonate during the neutralization reaction.

The neutralization reaction temperature varies depending on the subsequent method of obtaining sodium toluenesulfonate crystals, but it is preferably carried out at a temperature of 10 to 80°C.

Methods for obtaining crystals of sodium toluenesulfonate from the aqueous sodium toluenesulfonate solution obtained after the neutralization reaction include conventional method 2, such as evaporation concentration method.

Spray drying method, cooling crystallization method, etc. can be used.

The obtained sodium toluene sulfonate crystals do not contain any by-product sodium sulfate, which is seen in a method in which excess sulfuric acid is used in the reaction of toluene and sulfuric acid, so that it is possible to obtain high-purity crystals.

Sodium toluenesulfonate is thus obtained.

It is a stable, neutral crystal that does not require any special precautions in storage or handling.

Toluene separated from the aqueous solution of sodium toluene sulfonate can be used as is, or if necessary, distilled.

It is recovered and recycled for use in the sulfonation reaction.

[For production]

Many studies have already been conducted on the sulfonation reaction of aromatic compounds, typified by benzene and toluene, and it is classified as an equilibrium reaction, and the apparent reaction rate is proportional to the sulfuric acid concentration.

For this reason, in the method of using sulfuric acid in excess of toluene, it is necessary to reduce the decrease in the concentration of sulfuric acid due to water generated by the 9 reactions, and it is necessary to reduce the concentration of sulfuric acid by at least 2 to 3 times the molar amount relative to toluene. of sulfuric acid is required, and as a result, a large amount of waste liquid mainly consisting of sulfuric acid is produced as a by-product.

In addition, heating toluene in sulfuric acid not only produces by-products of ditolylsulfone, but also produces colored components with high boiling points, such as decomposition of toluene by sulfuric acid, as used in organic nitrogen analysis by the kale pool method. Therefore, decolorization and removal are necessary.

On the other hand, in the method of using an excess of toluene, it is necessary to azeotropically remove the water produced by the 9 reaction from the reaction system together with the toluene.

This invention uses an excess toluene method to avoid the troubles caused by the excess sulfuric acid method, thereby eliminating the by-product of ditolylsulfone and preventing the reaction solution from being colored due to decomposition of toluene. Sulfonation can be carried out very smoothly.

The reaction solution obtained in this reaction contains a large amount of unreacted toluene, but some or all of this reaction solution is used for crystallization of p-)luenesulfonic acid hydrate crystals. By limiting the amount of water added during crystallization to a smaller molar amount than the p-toluenesulfonic acid produced, highly pure p-)toluenesulfonic acid hydrate crystals can be obtained.

In addition, by using a small amount of water, the amount of water in the separated filtrate produced in the separation and acquisition of the crystals can also be kept to a small extent, which results in the reduction of the amount of water in the filtrate. It is possible to maintain high concentrations of toluenesulfonic acid and toluene in the liquid, and it is possible to obtain a soda salt with a high content of p-isomer in the subsequent production of sodium toluenesulfonate.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.

100 parts of 98% sulfuric acid was added dropwise over 1 hour to 322 parts (by weight; the same applies hereinafter) of toluene maintained under heating and reflux on a seed plate over 1 hour.

Stirring and refluxing were continued thereafter, and the water produced in reaction 1 was removed by azeotropy with toluene.

After about 4 hours, 20 parts of water was distilled off and the second reaction was completed.

The reaction solution was pale pink and was a solution in which toluene sulfonic acid was uniformly dissolved in toluene.

The obtained reaction product is toluenesulfonic acid (2 bodies 85
%, 0 bodies, 13%, 1 m bodies, 2%), and ditolyl sulfone was a trace amount.

After dividing the reaction solution into two parts and cooling one of them to 70"C,
5.5 parts of water was added dropwise while stirring.

This was cooled to 45°C for 3 hours, and the precipitated crystals were filtered and washed with 50 parts of toluene heated to 45°C.
Vacuum dried at 0°C for 3 hours to obtain p-+ with a purity of 99.7%.
55.0 parts of -luenesulfonic acid-water fD crystals were obtained.

By filtering these crystals, adding 10 parts of water to the filtrate and further filtration, the 9 bodies moistened with toluene were reduced to 81%.
Crystals containing toluenesulfonic acid were obtained.

The wet crystals were mixed with the previously divided reaction solution at a temperature of 55°C.
Then, 92 parts of water and 50.5 parts of a 48% caustic soda aqueous solution were added to neutralize the mixture.

Thereafter, the aqueous layer containing dissolved sodium toluenesulfonate generated by this neutralization is separated from the toluene layer, and the aqueous layer is evaporated (tl'a) to crystallize 117 sodium toluenesulfonate.
I got the department.

゛ As a result of analysis, this crystal has a purity of 99.8% of sodium toluene sulfonate, and the proportion of 9 crystals is 84.3%.
It was a crystal that did not contain sulfate groups.

Note that the toluene layer can be used as toluene for the reaction of toluene and sulfuric acid.

〔Effect of the invention〕

In this invention, p-
) Crystallization is performed by adding a smaller molar amount of water than toluenesulfonic acid to obtain p-toluenesulfonic acid as monohydrate crystals, and the separation filtrate alone or a combination of the separation filtrate and the reaction solution. A mixture or a mixture of toluenesulfonic acid crystals separated from the separated filtrate and the reaction solution is neutralized to obtain sodium toluenesulfonate p-) A method for co-production of toluenesulfonic acid and sodium toluenesulfonate. be.

Therefore, by crystallizing the reaction solution obtained by the reaction method using excess toluene with water in a smaller molar amount than the produced p-)luenesulfonic acid, p-)luenesulfonic acid with high p-isomer purity was efficiently produced. At the same time, by cleverly using the separated filtrate alone or this separated filtrate and a part of the reaction solution, toluene with a high p-isomer concentration can be obtained without leaving out all the toluenesulfonic acid component therein. It is excellent in that it can be converted into sodium sulfonate.

This method completely eliminates the complexity and loss in the process of the conventional method, which required production in each process, and produces p-)luene without the by-product of waste liquid as in the sulfuric acid excess method. Since sulfonic acid and its soda salt can be efficiently co-produced, the technical and economic benefits of metulid are significant, and the impact on the detergents, pharmaceuticals, agrochemicals, and polymer chemical industries that use these compounds is immeasurable. It is unknown.

Patent applicant: Toagosei Kagaku Kogyo Co., Ltd. Agent: Patent attorney Yuki 1) Completed written amendment to the Hong Kong procedure June 8, 1988 1, Indication of case: Patent Application No. 87872, 1987 2, Title of the invention p-) Manufacturing method for luenesulfonic acid and sodium toluenesulfonate 3, relationship with the case of the person making the amendment Patent applicant: 1-14-1 Nishi-Shinbashi, Minato-ku, Tokyo Toagosei Chemical Industry Co., Ltd. 4, Agent: HitOS Tokyo 5-12-1-5 Shinbashi, Minato-ku, "Detailed Description of the Invention" column 6 of the specification to be amended, contents of the amendment (11) ” should be amended to read, “In addition to meeting this request.”

(2) In the first and second lines of page 6 of the specification, the phrase "because ditolyl sulfone is produced as a by-product" is amended to "because ditolyl sulfone is produced as a by-product."

(3) In the first line of page 8 of the specification, the phrase ``due to a decrease in p-isomer purity'' is corrected to ``because p-isomer purity decreases.''

(4) On page 17, line 8 of the specification, the phrase "because we can efficiently produce products together" is amended to "because we can efficiently produce products together."

(5) On page 17, lines 8 and 9 of the specification, the phrase ``economic merits'' is amended to read ``economic merits''.

that's all

Claims (1)

[Claims] (1) Add water to part or all of the reaction solution containing toluenesulfonic acid obtained by reacting toluene and sulfuric acid with excess toluene, and crystallize p-toluenesulfonic acid as monohydrate from the reaction solution. At the same time, a filtrate from which the crystals are separated, a mixture of the filtrate and the reaction solution, or a mixture of toluenesulfonic acid crystals separated by adding water to the filtrate and the reaction solution are mixed with caustic soda. A method for producing p-toluenesulfonic acid and sodium toluenesulfonate, the method comprising neutralizing with sodium toluenesulfonate to obtain sodium toluenesulfonate.