CA1042014A - Process for producing a non-blackened phthalic acid from the corresponding tolualdehyde - Google Patents
Process for producing a non-blackened phthalic acid from the corresponding tolualdehydeInfo
- Publication number
- CA1042014A CA1042014A CA244,541A CA244541A CA1042014A CA 1042014 A CA1042014 A CA 1042014A CA 244541 A CA244541 A CA 244541A CA 1042014 A CA1042014 A CA 1042014A
- Authority
- CA
- Canada
- Prior art keywords
- tolualdehyde
- ppm
- reaction system
- manganese
- solvent
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/16—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation
- C07C51/21—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen
- C07C51/255—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen of compounds containing six-membered aromatic rings without ring-splitting
- C07C51/265—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen of compounds containing six-membered aromatic rings without ring-splitting having alkyl side chains which are oxidised to carboxyl groups
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
A PROCESS FOR PRODUCING A NON-BLACKENED PHTHALIC
ACID FROM THE CORRESPONDING TOLUALDEHYDE
Abstract of the Disclosure:
A process for producing a non-blackened phthalic acid from the corresponding tolualdehyde which comprises oxidizing the tolualdehyde with molecular oxygen or a molecular oxygen-containing gas in a liquid phase containing a lower aliphatic monocarboxylic acid as a solvent, and heavy metal salt(s) containing at least one manganese salt, especially both manganese and cobalt salts and at least one bromine com-pound as a catalyst, characterized in that the manganese salt is used in such an amount that the proportion of manganese atom in the reaction system is not more than 40 parts per million by weight based on the combined weight of solvent and water in the reaction system is disclosed.
ACID FROM THE CORRESPONDING TOLUALDEHYDE
Abstract of the Disclosure:
A process for producing a non-blackened phthalic acid from the corresponding tolualdehyde which comprises oxidizing the tolualdehyde with molecular oxygen or a molecular oxygen-containing gas in a liquid phase containing a lower aliphatic monocarboxylic acid as a solvent, and heavy metal salt(s) containing at least one manganese salt, especially both manganese and cobalt salts and at least one bromine com-pound as a catalyst, characterized in that the manganese salt is used in such an amount that the proportion of manganese atom in the reaction system is not more than 40 parts per million by weight based on the combined weight of solvent and water in the reaction system is disclosed.
Description
1()~;~0~4 This invention relat~s to a process for producing a phthalic acid which comprises oxidizing the corresponding tolua]dehyde with molecular oxygen or a molecular oxygen-containing gas in a liquid phase by using a lower aliphaticmonocarboxylic acid as a solvent, and a heavy metal salt(s) containing at least one manganese salt, and at least one bromine comp~und as a catalyst and more particularly relates to a process for producing a phthalic acid from the cor-responding tolualdehyde, characterized in that the manganesesalt is used in such an amount that the proportion of manga-nese atom in the reaction system is 40 ppm by weight or less based on the combined weight of solvent and water in the reaction system thereby preventing blackened of the result-ing phthalic acid.
Japanese Patent Publication No. 2666/1959 filed onMay 4~ 1955 discloses that when an at least one aliphatic group~substituted aromatic compound is oxidized with molecu- -lar oxygen or a molecular oxygen-containing gas in a liquid phase by using a lower aliphatic monocarboxylic acid as a solvent and heavy metal salt(s) containing at least one manganese sal-t and at least one bromine compound as a catalyst, the corresponding aromatic carboxylic acid is - formed. Each of terephthalic acid and isophthalic acid has been prepared from p-xylene and m-xylene on an industrial scale by using the above mentioned process.
Japanese Patent Publication No. 2666/1959 discloses that a manganese salt is an excellent catalyst for producing an aromatic carboxylic acid from the corresponding aliphatic ~0 group-substituted aromatic compound. The publication discloses that a cobalt salt also is an excellent catalyst.
$~ , .. ~ . .
' ` 1(~;~0'~
In case of oxidizing p-xylene with molecular oxygen or a molecular oxygen-containing gas in a liquid phase by using acetic acid, etc. as a solvent, and a catalyst consisting of a heavy metal salt and a bromine compound to obtain terephthalic acid, Journal of Industrial Chemistry, Vol.
` 70, 1967, page 1155 discloses that a cobalt salt is the most effective catalyst of the heavy metal salts, and that a manganese salt ranks next. Also, Organic Oxidation Reaction, written by Yoshio Kamiya, published by Gihodo in 1974 dis-closes that the heavy metal salts obtained by adding a manganese salt to a cobalt salt have a synergistic effect as a catalyst for producing terephthalic acid from p-xylene.
Japanese Patent Publication No. 36732/1970 filed on June 26, 1967 discloses that polymerizable terephthalic acid of high ` 15 purity can be obtained by oxidizing p-xylene and that a - cobalt salt has an excellent catalytic action for the oxi-- dization reaction. Considering these prior art techniques together, it was known that a mixture of a cobalt salt and ~ a manganese salt have excellent catalytic action for oxidiz-20 ing p-xylene with molecular oxygen or a molecular oxygen-containing gas in a liquid phase by using a lower aliphatic monocarboxylic acid as a solvent, and a bromine compound and a heavy metal salt as a catalyst to obtain terephthalic - acid.
Journal o~ Industrial Chemistry, Vol. 67, 1964, page - 1396 discloses that when p-xylene is oxidized in a system comprising a manganese salt as a metal component p-xylene is oxidized to terephthalic acid via p-toluic acid and 4-carboxy benzaldehyde (hereinunder abbreviated as 4CBA).
Therefore, it seems self-evident that terephthalic acid can ,,'~'' .
; - 3 -:`
.
~, ., ~ o~o~
be easily produced from p~tolualdehyde using the same catalyst as the one for producing terephthalic acid from p-xylene in the same way as the prior artO
The inventors of the present invention, however, have found that when p-tolualdehyde is oxidized in place of p-xylene under the same continuous oxidizing conditions as those under which p-xylene is oxidized to terephthalic acid, dark gray terephthalic acid is surprisingly formed.
In other words, we have found that a technical problem which does not occur in case of producing terephthalic acid from ~ :
p-xylene occurs when terephthalic acid is produced from p-tolualdehyde. We have also folmd that blackening of the resulting terephthalic acid is caused by mixing of the - m~nganese salt employed as one component of the catalyst in the resulting terephthalic acid. It is a matter of . ~
course that even if the dark gray terephthalic acid produced from p-tolualdehyde reacts with glycols, polyesters having . ~ .
high whiteness can not be obtained. It was also found that even if the dark gray terephthalic acid is washed with acetic acid, etc. the dark gray color can not be removed from the terephthalic acid. Similarly, we have found that neither recrystallization of the dark gray terephthalic acid in acetic acid or water, nor particular recrystalliza-. -tion as disclosed in Japanese Patent Publication No. 16860/
1966 on March 27, 1964 removes the dark gray from the terephthalic acid. In other words, it was found that industrially valuable terephthalic acid can not be obtained from p tolualdehyde as it is when p-xylene is oxidized to terephthalic acid.
In the prior art, terephthalic acid has been produced ~O~Z0~4 from p-xylene as a starting material on an industrial scale, because the technique of producing terephthalic acid from p-xylene has progressed by practicing the inventions dis-closed in Japanese Patent Publication Nos. 2666/1959 and 36732/1970.
P-xylene which is employed as a starting material ; for the production of terephthalic acid is produced by com-; plicated processes, such as isomerization of xylenes and separation of xylenes. On the other hand, it was known that p-tolualdehyde can be easily produced from toluene and carbon monoxide. Recently, p-tolualdehyde has been produced by reacting toluene with carbon monoxide in the presence of hydrogen fluoride and boron trifluoride as a catalyst as disclosed in Japanese Patent Publication No.
29760/1964. Toluene can be more easily produced on an industrial scale than xylene, For example, separation of toluene from aromatic hydrocarbons and purification of ` toluene are easier than those of p-xylene. Also, toluene is cheaper than p-xylene. Therefore, it is advantageous that p-tolualdehyde produced from toluene can be used as a starting material for the production of terephthalic acid.
However, as mentioned above, the technique for the production of terephthalic acid from p-xylene can not be applied to the technique for the production of terephthalic acid from p-- 25 tolualdehyde as it is.
.
The inventors of this invention have carried out a ; wide range of research to find an industrially valuable process for producing a phthalic acid which comprises oxidizing the corresponding tolualdehyde with molecular .
.:,.
.. '~
1()4;~014 oxygen or a molecular oxygen-containing gas in a liquid phase by using a lower aliphatic monocarboxylic acid as a solvent, and a heavy metal salt containing at least one manganese salt, and at least one bromine compound as a catalyst. As a result, we have found that in case of oxidizing p-tolualdehyde with molecular oxygen or a molecu-lar oxygen-containing gas in a liquid phase by using a lower aliphatic monocarboxylic acid as a solvent in the presence ofa heav~ metal saltcontaining at least one manganese salt, and a bromine compound to form terephthalic acid, the pro portion of manganese atom in the reaction system has a great influence on the blackering of terephthalic acid caused by -mixing of manganese therein.
We have found that a non-blackened phthalic acid can be produced from the corresponding tolualdehyde, when the ~` proportion of manganese atom in the reaction system is ` maintained at less than 40 ppm by weight based on the com- --bined weight of water and the solvent in the reaction system.
The solution consisting of water and solvent in the reaction system is hereinafter called a reaction solution. In other words, we have found that no blackening of the phthalic acid occurs under any conditions for oxidizing the corresponding tolualdehyde with molecular oxygen or a molecular oxygen-containing gas~ if the proportion of the manganese atom in the reaction system is maintained at less than 40 ppm based on the weight of the reaction solution. This invention is based on these discovery.
Therefore, an object of this invention is to provide a process for producing a non-blackened phthalic acid from the corresponding tolualdehyde.
.
.. ' . . : :.
~o~zo~
This invention relates to a process for producing a non-blackened phthalic acid from the corresponding tolualde-hyde which comprises oxidizing the tolualdehyde with molecu-lar oxygen or a molecular oxygen-containing gas in a liquid reaction system containing a lower aliphatic monocarboxylic acid as a solvent, and heavy metal salt(s) containing at least one manganese salt, especially both manganese and cobalt salts and at least one bromine compound as a catalyst, characterized in that the manganese salt is used in such an amount that the proportion of manganese atom in the reaction system is not more than 40 parts per million ~40 ppm) based on the weight of the reaction solution. The term "blackening of terephthalic acid" in the specification and the claims means that terephthalic acid in black, dark gray or grayish brown, etc. is formed.
~` It is critical to add to the reaction system the manganese salt in such an amount that the proportion of manganese atom in the reaction system is not more than 40 ppm based on the weight of the reaction solution, and prefer-ably the manganese salt is added in such an amount that the proportion of the manganese atom in the reaction system ranges from 5 ppm to 40 ppm based on the weight of the reaction solution. When p-tolualdehyde is oxidized in the presence of said solvent and said catalyst while maintaining the proportion of the manganese atom in the reaction system at less than 40 ppm based on the weight of the reaction solution, terephthalic acid which has ~igh whiteness and is industrially valuable can be produced. When the proportion of the manganese atom in the reaction system is more than - , :
109~ZQ~.
.. ......
40 ppm based on the weight of the reaction solution, dark gray terephthalic acid is produced from p-tolualdehyde under conventional conditions.
- The catalyst employed in this invention consists of heavy metal salt(s), such as a manganese salt and/or a cobalt salt, and a bromine compound. The heavy metal salt includes inorganic salt or organic salt of manganese, and inorganic or organic salt of cobalt. It is preferred that the heavy metal salt be soluble in the lower aliphatic monocarboxylic acid employed as a solvent.
The amount of the cobalt salt added to the reaction system and the amount of the bromine compound added to the reaction system are not critical in this invention. These components are used in a catalytic amount sufficient to oxidize a tolualdehyde to the corresponding phthalic acid. -~
Independent of the amount of the cobalt salt, the amount of the bromine compound and the water content in the reaction solution, a non-blackened phthalic acid can be produced -from the corresponding tolualdehyde by limiting the propor-tion of the manganese atom in the reaction system to a -~ specific value. In general, the cobalt salt may be used ; in such an amount that the proportion of cobalt atom ranges from 100 ppm to 5000 ppm based on the weight of the solvent.
The bromine compound includes an inorganic salt, such as, for example ammonium bromide, sodium bromide, potassium bromide or hydrogen bromide, etc. and an organic bromide, such as, for example tetrabromoethane or tetrabromo-p-xylene, etc. The bromine compound is used in such an amount that : the proportion of bromine atom in the reaction system ranges from 500 ppm to 5000 ppm based on the weight of the solvent.
. .
.-. ~
10420~L
Reaction temperature is not critical. However, elevated temperature accelerates the reaction and a temper-ature ranging from about 120C to about 240C is advanta-geously employed. The oxidization reaction of this invention is carried out in the liquid phase. Therefore, it is prefer-red that the oxidization reaction be carried out at one or superatmosphere so as to keep the tolualdehyde and the solvent introduced into the reaction system in the liquid state. The oxidization reaction is conveniently carried out at a pressure ranging from 1 to 50 atms.
Molecular oxygen or a molecular oxygen-containing gas is used as an oxidizing agent. From an economic point of view, air is the preferred oxidizing agent.
A lower aliphatic monocarboxylic acid9 such as acetic acid, propionic acid or butyric acid, etc. is conveniently used as the solvent. Acetic acid is preferred. The amount of the lower aliphatic monocarboxyl acid used is conveniently at least two times as much as the tolualdehyde on a weight basis.
The history of the tolualdehyde is not of a limiting nature to the process of this invention. In other words, all tolualdehydes, whatever the method which have been pre-- pared, can be used in the process of this invention, P-tolualdehyde obtained by reaction of toluene with carbon monoxide in the presence of hydrogen fluoride and boron trifluoride as a catalyst is preferably used as a starting material in the present process, because it is more available.
The present process is particularly suitable ~or oxidizing p-tolualdehyde to form terephthalic acid. This is because not only p-tolualdehyde is commercially available _ g _ :
. .
.
1~4ZO~L
and the resulting terephthalic acid is useful9 but also the effect of this invention is advantageous in case of the oxidation of p-tolualdehyde. This invention is more suitable for continuous or semi-continuous oxidization of p-tolualde-hyde.
The present lnvention is further illustrated by the ~ -following Examples and comparative Examples. However, this invention should not be limited by these examples, and the - changes and modifications within the spirit and scope of this invention can be effected. The percent, ppm and parts ~ ~
in the Examples are based on weight unless otherwise specified. ~ `
Example 1 Into a 500 m~ pressure reactor made of titanium equip- ~
ped with reflux condenser, stirring means, heating means, `
inlet for raw material, inlet for raw material gas and exit ~ `
for gas were charged 0.790 gr of cobalt acetate tetrahydrate, 0.0375 gr of manganese acetate tetrahydrate, 0.324 gr of sodium bromide and 208.8 gr of acetic acid. The proportions of Co, Mn and Br in the resulting mixture were in the following-Co proportion 890 ppm (based on solvent) Mn proportion 40 ppm (based on reaction solution) ~r proportion 1200 ppm (based on solvent) The pressure in the reactor was raised to 10 Kg/cm2G
by blowing nitrogen gas into the reactor, and thereafter thetemperature of the reactor was raised to 200C by heating means. Thereafter, 80 gr of p-tolualdehyde was added to the `
reactor at 200C at 20 Kg/cm2 over one hour while blowing air into the reactor~ After addition of p-tolualdehyde was completed, air was blown into the reactor for another five ., ,~04ZO:~
minutes. Thereafter, the reactor was cooled to room temper-ature, and the resulting reaction product was removed.
The product in a slurry state was filtered and cake was separated from the filtrate. The cake was washed with - 5 acetic acid and then water. The resulting terephthalic acid was dried at 110C. The yield of terephthalic acid and the properties thereof are shown in Table 1.
Example 2 The procedure of Example 1 was repeated except that the proportion of the manganese was 20 ppm based on the reaction solution. The yield of the resulting terephthalic acid and the properties thereof are shown in Table 1.
- Example 3 The procedure of Example 1 was repeated except that the proportion of the manganese was 10 ppm based on the reaction solution. The yield of the resulting terephthalic acid and the properties thereof are shown in Table 1.
Comparative Example 1 The procedure of Example 1 was repeated except that the proportion of the manganese was 90 ppm based on the reaction solution. The yield of the resulting terephthalic acid and the properties thereof are shown in Table 1.
Comparative ExamPle 2 The procedure of Example 1 was repeated except that - 25 the proportion of Co, Br and Mn were 890 ppm, 1200 ppm and 60 ppm based on the reaction solution. respectively. The ... :.
yield of the resulting terephthalic acid and the properties thereof are shown in Table 1.
The water content in the reaction solution in Examples 1 through 3 and Comparative Examples 1 and 2 was 16.3% at the . ~ .
'~
., .
10~0 :a~
end point of the reaction.
_ Properties of the resulting Yield of Mn propor- terephthalic acid terephthalic N tion based or _ _ acid o. the reaction Appear- 4CBA Alkaline Ash ~percent on solutionance content color* content a mole basis) (ppm) (ppm) . . .
Example 1 40 white 750 0.518 5.2 95.8 Example 2 20 white 700 0.430 4.1 96.0 . ..
Example 3 10 white B70 0.442 4.3 95.4 Comparative _ _ Grayish . ~
: Example 1 brown 1000 ~ 46 95.1 Comparative Pale Example 2 60yellow 970 1.84 29 95.7 * 2 gr of the terephthalic acid was dissolved in 25 m~
of a 2 normal solution of potassium hydroxide. The resulting reaction product was placed in 50 mm cell. The cell was exposed to light having wavelength of 340 m~ to determine optical density. The alkaline color expresses the resulting optical density.
Each of the terephthalic acid obtained in Examples 1 through 3 was hydrogenated with molecular hydrogen in the presence of a catalyst and was recrystallized in hot water as disclosed in Japanese Patent Publication No. 16860/1966.
The solution was lowered to room temperature, and the terephthalic acid was removed from the solution. The resulting terephthalic acid had the following properties.
Appearance white 4CBA contained in the less than 10 ppm terephthalic acid alkaline color less than 0.090 . ~
The resulting purified terephthalic acid reacted with ethylene glycol to form polyethylene terephthalate.
The resulting polyethylene terephthalate was clear.
The terephthalic acid obtained in Comparative Example 1 was hydrogenated and was recrystallized in hot water as disclosed in Japanese Patent Publication No. 16860/1966.
The properties of the resulting terephthalic acid were in the following:
Appearance dark gray 4CBA contained in the 10 ppm terephthalic acid Alkaline color ~
The terephthalic acid which was hydrogenated and - recrystallized reacted with ethylene glycol to form poly--- ethylene terephthalate. The resulting polyethylene tere-phthalate was dark gray.
Example 4 Into the reactor employed in Example 1 were charged 0.790 gr of cobalt acetate tetrahydrate 9 0.0262 gr of man-ganese acetate, 0.324 gr of sodium bromide and 208.9 gr of ` 20 acetic acid (having water content therein of 5%). The - contents of Co, Mn and Br in the resulting mixture were ; in the following proportions~
Co proportion 890 ppm (based on solvent) Mn proportion 28 ppm (based on reaction solution) `
v 25 Br proportion 1200 ppm (based on solvent) The pressure in the reactor was raised to 10 Kg/cm by blowing nitrogen gas into the reactor, and thereafter the temperature of the reactor was raised to 200C. Thereafter, 80 gr of p-tolualdehyde was added to the reactor at 190C
.
~, .
: ', :
.
.
at 18 Kg/cm2G over one hour while blowing air into the reactor. After addition of p tolualdehyde was completed, air was blown into the reactor for another five minutes.
Thereafter, the reactor was cooled to room temperature, and the resulting reaction product was removed.
The product in a slurry state was filtered and cake was separated from the filt-rate. The cake was washed with acetic acid and then water. The resulting terephthalic acid was dried at 110C. The yield of the terephthalic acid and the properties thereof are shown in Table 2.
; Examples 5 and 6 The procedures of Example 4 were repeated except that acetic acid having the water content of 10~ (Example 5) or 15% (Example 6) was used. The yield of the resulting terephthalic acid and the properties thereof are shown in Table 2.
ComParative Ex~ ~3 ; The procedure of Example 4 was repeated except that ,'7' the proportion of the manganese was 60 ppm based on the reaction solution. The yield of the resulting terephthalic acid and the properties thereof are shown in Table 2.
Comparative Example 4 The procedure of Example 4 was repeated except that the proportion of the manganese was 60 ppm based on the reaction solution, and acetic acid having the water content of 10% was used. The yield of the resulting terephthalic acid and the properties thereof are shown in Table 2.
The procedure of Example 4 was repeated except that - 30 the proportion of the manganese was 60 ppm based on the .
lO~ZOl~
reaction solution, and acetic acid having the water content of 15% was used. The yield of the resulting terephthalic - acid and the properties thereof are shown in Table 2.
~ TABLE 2 .
; Properties of the resulting Yield of l~Jater terephthalic acid terephthalic No.content Appear- 4CBA Alkaline Ash acid acid added ance c ntent color content a mole basis) Example 4 white 990 0.513 4.5 96.6 Example 510 white 1180 0.573 4.8 96.0 . ..
Example 615 whlte 1350 0.700 6.0 95.0 Comparative grayish Example 3 5 brown 1030 ~0 53 95.2 ., _ _ . . . .
Comparative Example 410 gray 1390 64 95.0 Comparative dark Example 515 gray 1500 ~o 95.0 94.1 .. j l . ~ ,. . ,_ Each of the terephthalic acid obtained in Examples . 4 - 6 was hydrogenated and was recrystallized as disclosed in Japanese Patent Publication No. 16860/1965, whereby white '~ terephthalic acid crystals were obtained in all cases.
On the other hand, though each of the terephthalic acid obtained in Comparative Examples 3 - 5 was hydrogenated and was recrystallized as disclosed in Japanese Patent Publication No. 16860/1966, white terephthalic acid crystals can not be obtained. Alkaline color of the purified tere-phthalic acid was ~ .
Example 7 .
Into the reactor employed in Example 1 were charged 1.58 gr of cobalt acetate tetrahydrate, 0.0262 gr of manga-nese acetate 9 0.324 gr of sodium bromide and 208.1 gr of ~4'Z~14 .
- acetic acid having the water content of 5%. The proportion of Co, Mn and Br in the resulting mixture were in the following:
Co proportion 1780 ppm (based on solvent) Mn proportion 28 ppm (based on reaction solution) Br proportion 1200 ppm (based on solvent) The pressure in the reactor was raised to 10 Kg/cm ~ by blowing nitrogen gas into the reactor, and thereafter : the temperature in the reactor was raised to 200C. There-. : .
` 10 after, 40 gr of p-tolualdehyde was added to the reactor at 200C at 18 Kg/cm2G over one hour while blowing air into - the reactor. After addition of p-tolualdehyde was completed, air was blown into the reactor for another five minutes.
The resulting reaction product was subjected to the same treatment as used in Example 1. The yield of the resulting terephthalic acid and the properties thereof are shown in Table 3.
Com~arative Example 6 . .
The procedure of Example 7 was repeated except that the proportion of the manganese was 90 ppm based on the ;- reaction solution. The yield of the resulting terephthalic . .
;; acid and the properties thereof are shown in Table 3.
, ..,.
Proportion Properties of the resulting Yield of of Mn terephthalic acid terephthali based on the ~acid No. reaction Appear- 4CBA Alkaline Ash (percent solution ance content color content on a mole (ppm) (ppm) (ppm) basis) '.' .
Example 7 28 white 290 0.294 4.5 94.2 . . . . . .
Comparative dark Example 6 90 gray 850 ~ 87 94.0 _ _ l .. ~ .
, '"' 1~4ZOl~
Though the terephthalic acid obtained in Comparative Example 6 was hydrogenated and recrystallized9 the dark gray color could not be removed from the terephthallc acid.
Example 8 Into the reactor employed in Example 1 were charged 3.16 gr of cobalt acetate tetrahydrate, 0.0375 gr of manga-nese acetate, 1.026 gr of sodium bromide and 205.8 gr of acetic acid having the water content of 5~0. The proportion - of Co, Mn and Br in the resulting mixture were in the following:
Co proportion 3560 ppm (based on solvent) Mn proportion 40 ppm (based on reaction solution) ~ Br proportion 3600 ppm (based on solvent) :
The pressure in the reactor was raised to 10 Kg/cm2 ~ :
by blowing nitrogen gas into the reactor, and thereafter the temperature of the reactor was raised to 200C, There-. after, 30 gr of p-tolualdehyde was added to the reactor at ~ -;~. 205C at 20 Kg/cm2G over one hour while blowing air into the reactor. After addition of p-tolualdehyde was completed, air was blown into the reactor for another five minutes.
The resulting reaction product was subjected to the same .. ~ treatment as that of Example 1. The yield of the resulting terephthalic acid and the properties thereof are shown in the following Appearance white 4CBA con-tent 210 ppm Alkaline color 0.100 Ash content 3.2 ppm . Yield of tere--. phthalic acid 95.0% on a mole basis ' .- ~
..
, .
- . . .
10~0~4 Example 9 Continuous oxidization of p-tolualdehyde was carried out in an apparatus for continuous oxidization reaction comprising a 2.5 liter pressure reactor made of titanium equipped with refl~x condenser, stirring means, heating means, inlet for raw material, inlet for raw material gas, exit for gas, exit for reaction product, and two receivers for the reaction product connected to the exit for reaction product of the reactor.
Into the reactor were charged 500 gr of acetic acid having a water content of 15%, 1.26 gr of cobalt acetate tetrahydrate, 0.087 gr of manganese acetate tetrahydrate . and 0.515 gr of sodium bromide. The pressure in the reactor : was raised to 10 Kg/cm G, and then the temperature of the reactor was raised to 200C. Feeding solution havlng the ~ -following components was prepared in ~nother container:
. Cobalt acetate tetrahydrate (Co content ~ in the feeding solution 594 ppm) -~ manganese acetate tetrahydrate (Mn -content in the feeding solution 39.1 ppm) sodium bromide (Br content in the feeding solution 805 ppm) The feeding solution was continuously fed into the reactor at the rate of 780 gr/hr, and p-tolualdehyde was continuously fed into the reactor at the rate of 260 gr/hr at 200C at 16.5 Kg/cm2 gauge. At the same time, air was blown into the reactor at such a rate as to maintain the oxygen content in the gas withdrawn from the exit for gas of the reactor at ~%. The reaction product was continuously withdrawn into the receiver so as to keep the level of the ` reaction solution constant.
':`, '", . . . ~ ., 104~0~4 The reaction product in a slurry state was filtered, and cake was separated from the filtrate. The cake was - washed with acetic acid and then water, and was dried to obtain terephthalic acid. The yield of terephthalic acid 5 was 94.4% on the mole basis. The terephthalic acid had the following properties:
Appearance white 4CBA content 184~ ppm Alkaline color 0.801 -~ 10 Ash content 3.3 ppm Mn in the ash based on the acid 1~6 ppm - The resulting terephthalic acid was hydrogenated with molecular hydrogen in the presence of a catalyst and was recrystalli7ed in hot water as disclosed in Japanese Patent : 15 Publication No. 16860/1966. The purified terephthalic acid , had the following properties-J`.'' Appearance white `
4CBA content less than 10 ppm Alkaline color 0.090 ~ 20 The purified terephthalic acid reacted with polyethyl-- ~ ene glycol to form polyethylene terephthalate. The resulting polyethylene terephthalate was clear.
Comparative Example 7 The procedure of Example 9 was repeated except that the feeding solution having Co content of 594 ppm, Mn content of 55.4 ppm and Br content of 805 ppm was used.
The properties of the resulting terephthalic acid ` and the yield thereof were in the followingo Appearance gray 4CBA content 1880 ppm ... .
: . , .
.: 9 .. ..
; .~,.
:, .
10420~4 Alkaline color Ash content 47.4 ppm Mn304 in the ash 35.0 ppm based on the telephthalic - acid - Yield 92.0% on a mole basis The water content in the reaction solution was 16.7%
at the end point of the reaction. Though the resulting terephthalic acid was hydrogenated and was recrystallized ` as disclosed in Japanese Patent Publication No. 16860/1966, ~ the gray color was not removed from the terephthalic acid.
- 10 The purified terephthalic acid reacted with ethylene glycol to form polyethylene terephthalate. However, the resulting polyethylene terephthalate was gray.
' "
. '-' . .
,~ . -; .
'''-.'.' :' ' :', ,' .' ~
:
, " ~
_ 20 -.
. .
. :
Japanese Patent Publication No. 2666/1959 filed onMay 4~ 1955 discloses that when an at least one aliphatic group~substituted aromatic compound is oxidized with molecu- -lar oxygen or a molecular oxygen-containing gas in a liquid phase by using a lower aliphatic monocarboxylic acid as a solvent and heavy metal salt(s) containing at least one manganese sal-t and at least one bromine compound as a catalyst, the corresponding aromatic carboxylic acid is - formed. Each of terephthalic acid and isophthalic acid has been prepared from p-xylene and m-xylene on an industrial scale by using the above mentioned process.
Japanese Patent Publication No. 2666/1959 discloses that a manganese salt is an excellent catalyst for producing an aromatic carboxylic acid from the corresponding aliphatic ~0 group-substituted aromatic compound. The publication discloses that a cobalt salt also is an excellent catalyst.
$~ , .. ~ . .
' ` 1(~;~0'~
In case of oxidizing p-xylene with molecular oxygen or a molecular oxygen-containing gas in a liquid phase by using acetic acid, etc. as a solvent, and a catalyst consisting of a heavy metal salt and a bromine compound to obtain terephthalic acid, Journal of Industrial Chemistry, Vol.
` 70, 1967, page 1155 discloses that a cobalt salt is the most effective catalyst of the heavy metal salts, and that a manganese salt ranks next. Also, Organic Oxidation Reaction, written by Yoshio Kamiya, published by Gihodo in 1974 dis-closes that the heavy metal salts obtained by adding a manganese salt to a cobalt salt have a synergistic effect as a catalyst for producing terephthalic acid from p-xylene.
Japanese Patent Publication No. 36732/1970 filed on June 26, 1967 discloses that polymerizable terephthalic acid of high ` 15 purity can be obtained by oxidizing p-xylene and that a - cobalt salt has an excellent catalytic action for the oxi-- dization reaction. Considering these prior art techniques together, it was known that a mixture of a cobalt salt and ~ a manganese salt have excellent catalytic action for oxidiz-20 ing p-xylene with molecular oxygen or a molecular oxygen-containing gas in a liquid phase by using a lower aliphatic monocarboxylic acid as a solvent, and a bromine compound and a heavy metal salt as a catalyst to obtain terephthalic - acid.
Journal o~ Industrial Chemistry, Vol. 67, 1964, page - 1396 discloses that when p-xylene is oxidized in a system comprising a manganese salt as a metal component p-xylene is oxidized to terephthalic acid via p-toluic acid and 4-carboxy benzaldehyde (hereinunder abbreviated as 4CBA).
Therefore, it seems self-evident that terephthalic acid can ,,'~'' .
; - 3 -:`
.
~, ., ~ o~o~
be easily produced from p~tolualdehyde using the same catalyst as the one for producing terephthalic acid from p-xylene in the same way as the prior artO
The inventors of the present invention, however, have found that when p-tolualdehyde is oxidized in place of p-xylene under the same continuous oxidizing conditions as those under which p-xylene is oxidized to terephthalic acid, dark gray terephthalic acid is surprisingly formed.
In other words, we have found that a technical problem which does not occur in case of producing terephthalic acid from ~ :
p-xylene occurs when terephthalic acid is produced from p-tolualdehyde. We have also folmd that blackening of the resulting terephthalic acid is caused by mixing of the - m~nganese salt employed as one component of the catalyst in the resulting terephthalic acid. It is a matter of . ~
course that even if the dark gray terephthalic acid produced from p-tolualdehyde reacts with glycols, polyesters having . ~ .
high whiteness can not be obtained. It was also found that even if the dark gray terephthalic acid is washed with acetic acid, etc. the dark gray color can not be removed from the terephthalic acid. Similarly, we have found that neither recrystallization of the dark gray terephthalic acid in acetic acid or water, nor particular recrystalliza-. -tion as disclosed in Japanese Patent Publication No. 16860/
1966 on March 27, 1964 removes the dark gray from the terephthalic acid. In other words, it was found that industrially valuable terephthalic acid can not be obtained from p tolualdehyde as it is when p-xylene is oxidized to terephthalic acid.
In the prior art, terephthalic acid has been produced ~O~Z0~4 from p-xylene as a starting material on an industrial scale, because the technique of producing terephthalic acid from p-xylene has progressed by practicing the inventions dis-closed in Japanese Patent Publication Nos. 2666/1959 and 36732/1970.
P-xylene which is employed as a starting material ; for the production of terephthalic acid is produced by com-; plicated processes, such as isomerization of xylenes and separation of xylenes. On the other hand, it was known that p-tolualdehyde can be easily produced from toluene and carbon monoxide. Recently, p-tolualdehyde has been produced by reacting toluene with carbon monoxide in the presence of hydrogen fluoride and boron trifluoride as a catalyst as disclosed in Japanese Patent Publication No.
29760/1964. Toluene can be more easily produced on an industrial scale than xylene, For example, separation of toluene from aromatic hydrocarbons and purification of ` toluene are easier than those of p-xylene. Also, toluene is cheaper than p-xylene. Therefore, it is advantageous that p-tolualdehyde produced from toluene can be used as a starting material for the production of terephthalic acid.
However, as mentioned above, the technique for the production of terephthalic acid from p-xylene can not be applied to the technique for the production of terephthalic acid from p-- 25 tolualdehyde as it is.
.
The inventors of this invention have carried out a ; wide range of research to find an industrially valuable process for producing a phthalic acid which comprises oxidizing the corresponding tolualdehyde with molecular .
.:,.
.. '~
1()4;~014 oxygen or a molecular oxygen-containing gas in a liquid phase by using a lower aliphatic monocarboxylic acid as a solvent, and a heavy metal salt containing at least one manganese salt, and at least one bromine compound as a catalyst. As a result, we have found that in case of oxidizing p-tolualdehyde with molecular oxygen or a molecu-lar oxygen-containing gas in a liquid phase by using a lower aliphatic monocarboxylic acid as a solvent in the presence ofa heav~ metal saltcontaining at least one manganese salt, and a bromine compound to form terephthalic acid, the pro portion of manganese atom in the reaction system has a great influence on the blackering of terephthalic acid caused by -mixing of manganese therein.
We have found that a non-blackened phthalic acid can be produced from the corresponding tolualdehyde, when the ~` proportion of manganese atom in the reaction system is ` maintained at less than 40 ppm by weight based on the com- --bined weight of water and the solvent in the reaction system.
The solution consisting of water and solvent in the reaction system is hereinafter called a reaction solution. In other words, we have found that no blackening of the phthalic acid occurs under any conditions for oxidizing the corresponding tolualdehyde with molecular oxygen or a molecular oxygen-containing gas~ if the proportion of the manganese atom in the reaction system is maintained at less than 40 ppm based on the weight of the reaction solution. This invention is based on these discovery.
Therefore, an object of this invention is to provide a process for producing a non-blackened phthalic acid from the corresponding tolualdehyde.
.
.. ' . . : :.
~o~zo~
This invention relates to a process for producing a non-blackened phthalic acid from the corresponding tolualde-hyde which comprises oxidizing the tolualdehyde with molecu-lar oxygen or a molecular oxygen-containing gas in a liquid reaction system containing a lower aliphatic monocarboxylic acid as a solvent, and heavy metal salt(s) containing at least one manganese salt, especially both manganese and cobalt salts and at least one bromine compound as a catalyst, characterized in that the manganese salt is used in such an amount that the proportion of manganese atom in the reaction system is not more than 40 parts per million ~40 ppm) based on the weight of the reaction solution. The term "blackening of terephthalic acid" in the specification and the claims means that terephthalic acid in black, dark gray or grayish brown, etc. is formed.
~` It is critical to add to the reaction system the manganese salt in such an amount that the proportion of manganese atom in the reaction system is not more than 40 ppm based on the weight of the reaction solution, and prefer-ably the manganese salt is added in such an amount that the proportion of the manganese atom in the reaction system ranges from 5 ppm to 40 ppm based on the weight of the reaction solution. When p-tolualdehyde is oxidized in the presence of said solvent and said catalyst while maintaining the proportion of the manganese atom in the reaction system at less than 40 ppm based on the weight of the reaction solution, terephthalic acid which has ~igh whiteness and is industrially valuable can be produced. When the proportion of the manganese atom in the reaction system is more than - , :
109~ZQ~.
.. ......
40 ppm based on the weight of the reaction solution, dark gray terephthalic acid is produced from p-tolualdehyde under conventional conditions.
- The catalyst employed in this invention consists of heavy metal salt(s), such as a manganese salt and/or a cobalt salt, and a bromine compound. The heavy metal salt includes inorganic salt or organic salt of manganese, and inorganic or organic salt of cobalt. It is preferred that the heavy metal salt be soluble in the lower aliphatic monocarboxylic acid employed as a solvent.
The amount of the cobalt salt added to the reaction system and the amount of the bromine compound added to the reaction system are not critical in this invention. These components are used in a catalytic amount sufficient to oxidize a tolualdehyde to the corresponding phthalic acid. -~
Independent of the amount of the cobalt salt, the amount of the bromine compound and the water content in the reaction solution, a non-blackened phthalic acid can be produced -from the corresponding tolualdehyde by limiting the propor-tion of the manganese atom in the reaction system to a -~ specific value. In general, the cobalt salt may be used ; in such an amount that the proportion of cobalt atom ranges from 100 ppm to 5000 ppm based on the weight of the solvent.
The bromine compound includes an inorganic salt, such as, for example ammonium bromide, sodium bromide, potassium bromide or hydrogen bromide, etc. and an organic bromide, such as, for example tetrabromoethane or tetrabromo-p-xylene, etc. The bromine compound is used in such an amount that : the proportion of bromine atom in the reaction system ranges from 500 ppm to 5000 ppm based on the weight of the solvent.
. .
.-. ~
10420~L
Reaction temperature is not critical. However, elevated temperature accelerates the reaction and a temper-ature ranging from about 120C to about 240C is advanta-geously employed. The oxidization reaction of this invention is carried out in the liquid phase. Therefore, it is prefer-red that the oxidization reaction be carried out at one or superatmosphere so as to keep the tolualdehyde and the solvent introduced into the reaction system in the liquid state. The oxidization reaction is conveniently carried out at a pressure ranging from 1 to 50 atms.
Molecular oxygen or a molecular oxygen-containing gas is used as an oxidizing agent. From an economic point of view, air is the preferred oxidizing agent.
A lower aliphatic monocarboxylic acid9 such as acetic acid, propionic acid or butyric acid, etc. is conveniently used as the solvent. Acetic acid is preferred. The amount of the lower aliphatic monocarboxyl acid used is conveniently at least two times as much as the tolualdehyde on a weight basis.
The history of the tolualdehyde is not of a limiting nature to the process of this invention. In other words, all tolualdehydes, whatever the method which have been pre-- pared, can be used in the process of this invention, P-tolualdehyde obtained by reaction of toluene with carbon monoxide in the presence of hydrogen fluoride and boron trifluoride as a catalyst is preferably used as a starting material in the present process, because it is more available.
The present process is particularly suitable ~or oxidizing p-tolualdehyde to form terephthalic acid. This is because not only p-tolualdehyde is commercially available _ g _ :
. .
.
1~4ZO~L
and the resulting terephthalic acid is useful9 but also the effect of this invention is advantageous in case of the oxidation of p-tolualdehyde. This invention is more suitable for continuous or semi-continuous oxidization of p-tolualde-hyde.
The present lnvention is further illustrated by the ~ -following Examples and comparative Examples. However, this invention should not be limited by these examples, and the - changes and modifications within the spirit and scope of this invention can be effected. The percent, ppm and parts ~ ~
in the Examples are based on weight unless otherwise specified. ~ `
Example 1 Into a 500 m~ pressure reactor made of titanium equip- ~
ped with reflux condenser, stirring means, heating means, `
inlet for raw material, inlet for raw material gas and exit ~ `
for gas were charged 0.790 gr of cobalt acetate tetrahydrate, 0.0375 gr of manganese acetate tetrahydrate, 0.324 gr of sodium bromide and 208.8 gr of acetic acid. The proportions of Co, Mn and Br in the resulting mixture were in the following-Co proportion 890 ppm (based on solvent) Mn proportion 40 ppm (based on reaction solution) ~r proportion 1200 ppm (based on solvent) The pressure in the reactor was raised to 10 Kg/cm2G
by blowing nitrogen gas into the reactor, and thereafter thetemperature of the reactor was raised to 200C by heating means. Thereafter, 80 gr of p-tolualdehyde was added to the `
reactor at 200C at 20 Kg/cm2 over one hour while blowing air into the reactor~ After addition of p-tolualdehyde was completed, air was blown into the reactor for another five ., ,~04ZO:~
minutes. Thereafter, the reactor was cooled to room temper-ature, and the resulting reaction product was removed.
The product in a slurry state was filtered and cake was separated from the filtrate. The cake was washed with - 5 acetic acid and then water. The resulting terephthalic acid was dried at 110C. The yield of terephthalic acid and the properties thereof are shown in Table 1.
Example 2 The procedure of Example 1 was repeated except that the proportion of the manganese was 20 ppm based on the reaction solution. The yield of the resulting terephthalic acid and the properties thereof are shown in Table 1.
- Example 3 The procedure of Example 1 was repeated except that the proportion of the manganese was 10 ppm based on the reaction solution. The yield of the resulting terephthalic acid and the properties thereof are shown in Table 1.
Comparative Example 1 The procedure of Example 1 was repeated except that the proportion of the manganese was 90 ppm based on the reaction solution. The yield of the resulting terephthalic acid and the properties thereof are shown in Table 1.
Comparative ExamPle 2 The procedure of Example 1 was repeated except that - 25 the proportion of Co, Br and Mn were 890 ppm, 1200 ppm and 60 ppm based on the reaction solution. respectively. The ... :.
yield of the resulting terephthalic acid and the properties thereof are shown in Table 1.
The water content in the reaction solution in Examples 1 through 3 and Comparative Examples 1 and 2 was 16.3% at the . ~ .
'~
., .
10~0 :a~
end point of the reaction.
_ Properties of the resulting Yield of Mn propor- terephthalic acid terephthalic N tion based or _ _ acid o. the reaction Appear- 4CBA Alkaline Ash ~percent on solutionance content color* content a mole basis) (ppm) (ppm) . . .
Example 1 40 white 750 0.518 5.2 95.8 Example 2 20 white 700 0.430 4.1 96.0 . ..
Example 3 10 white B70 0.442 4.3 95.4 Comparative _ _ Grayish . ~
: Example 1 brown 1000 ~ 46 95.1 Comparative Pale Example 2 60yellow 970 1.84 29 95.7 * 2 gr of the terephthalic acid was dissolved in 25 m~
of a 2 normal solution of potassium hydroxide. The resulting reaction product was placed in 50 mm cell. The cell was exposed to light having wavelength of 340 m~ to determine optical density. The alkaline color expresses the resulting optical density.
Each of the terephthalic acid obtained in Examples 1 through 3 was hydrogenated with molecular hydrogen in the presence of a catalyst and was recrystallized in hot water as disclosed in Japanese Patent Publication No. 16860/1966.
The solution was lowered to room temperature, and the terephthalic acid was removed from the solution. The resulting terephthalic acid had the following properties.
Appearance white 4CBA contained in the less than 10 ppm terephthalic acid alkaline color less than 0.090 . ~
The resulting purified terephthalic acid reacted with ethylene glycol to form polyethylene terephthalate.
The resulting polyethylene terephthalate was clear.
The terephthalic acid obtained in Comparative Example 1 was hydrogenated and was recrystallized in hot water as disclosed in Japanese Patent Publication No. 16860/1966.
The properties of the resulting terephthalic acid were in the following:
Appearance dark gray 4CBA contained in the 10 ppm terephthalic acid Alkaline color ~
The terephthalic acid which was hydrogenated and - recrystallized reacted with ethylene glycol to form poly--- ethylene terephthalate. The resulting polyethylene tere-phthalate was dark gray.
Example 4 Into the reactor employed in Example 1 were charged 0.790 gr of cobalt acetate tetrahydrate 9 0.0262 gr of man-ganese acetate, 0.324 gr of sodium bromide and 208.9 gr of ` 20 acetic acid (having water content therein of 5%). The - contents of Co, Mn and Br in the resulting mixture were ; in the following proportions~
Co proportion 890 ppm (based on solvent) Mn proportion 28 ppm (based on reaction solution) `
v 25 Br proportion 1200 ppm (based on solvent) The pressure in the reactor was raised to 10 Kg/cm by blowing nitrogen gas into the reactor, and thereafter the temperature of the reactor was raised to 200C. Thereafter, 80 gr of p-tolualdehyde was added to the reactor at 190C
.
~, .
: ', :
.
.
at 18 Kg/cm2G over one hour while blowing air into the reactor. After addition of p tolualdehyde was completed, air was blown into the reactor for another five minutes.
Thereafter, the reactor was cooled to room temperature, and the resulting reaction product was removed.
The product in a slurry state was filtered and cake was separated from the filt-rate. The cake was washed with acetic acid and then water. The resulting terephthalic acid was dried at 110C. The yield of the terephthalic acid and the properties thereof are shown in Table 2.
; Examples 5 and 6 The procedures of Example 4 were repeated except that acetic acid having the water content of 10~ (Example 5) or 15% (Example 6) was used. The yield of the resulting terephthalic acid and the properties thereof are shown in Table 2.
ComParative Ex~ ~3 ; The procedure of Example 4 was repeated except that ,'7' the proportion of the manganese was 60 ppm based on the reaction solution. The yield of the resulting terephthalic acid and the properties thereof are shown in Table 2.
Comparative Example 4 The procedure of Example 4 was repeated except that the proportion of the manganese was 60 ppm based on the reaction solution, and acetic acid having the water content of 10% was used. The yield of the resulting terephthalic acid and the properties thereof are shown in Table 2.
The procedure of Example 4 was repeated except that - 30 the proportion of the manganese was 60 ppm based on the .
lO~ZOl~
reaction solution, and acetic acid having the water content of 15% was used. The yield of the resulting terephthalic - acid and the properties thereof are shown in Table 2.
~ TABLE 2 .
; Properties of the resulting Yield of l~Jater terephthalic acid terephthalic No.content Appear- 4CBA Alkaline Ash acid acid added ance c ntent color content a mole basis) Example 4 white 990 0.513 4.5 96.6 Example 510 white 1180 0.573 4.8 96.0 . ..
Example 615 whlte 1350 0.700 6.0 95.0 Comparative grayish Example 3 5 brown 1030 ~0 53 95.2 ., _ _ . . . .
Comparative Example 410 gray 1390 64 95.0 Comparative dark Example 515 gray 1500 ~o 95.0 94.1 .. j l . ~ ,. . ,_ Each of the terephthalic acid obtained in Examples . 4 - 6 was hydrogenated and was recrystallized as disclosed in Japanese Patent Publication No. 16860/1965, whereby white '~ terephthalic acid crystals were obtained in all cases.
On the other hand, though each of the terephthalic acid obtained in Comparative Examples 3 - 5 was hydrogenated and was recrystallized as disclosed in Japanese Patent Publication No. 16860/1966, white terephthalic acid crystals can not be obtained. Alkaline color of the purified tere-phthalic acid was ~ .
Example 7 .
Into the reactor employed in Example 1 were charged 1.58 gr of cobalt acetate tetrahydrate, 0.0262 gr of manga-nese acetate 9 0.324 gr of sodium bromide and 208.1 gr of ~4'Z~14 .
- acetic acid having the water content of 5%. The proportion of Co, Mn and Br in the resulting mixture were in the following:
Co proportion 1780 ppm (based on solvent) Mn proportion 28 ppm (based on reaction solution) Br proportion 1200 ppm (based on solvent) The pressure in the reactor was raised to 10 Kg/cm ~ by blowing nitrogen gas into the reactor, and thereafter : the temperature in the reactor was raised to 200C. There-. : .
` 10 after, 40 gr of p-tolualdehyde was added to the reactor at 200C at 18 Kg/cm2G over one hour while blowing air into - the reactor. After addition of p-tolualdehyde was completed, air was blown into the reactor for another five minutes.
The resulting reaction product was subjected to the same treatment as used in Example 1. The yield of the resulting terephthalic acid and the properties thereof are shown in Table 3.
Com~arative Example 6 . .
The procedure of Example 7 was repeated except that the proportion of the manganese was 90 ppm based on the ;- reaction solution. The yield of the resulting terephthalic . .
;; acid and the properties thereof are shown in Table 3.
, ..,.
Proportion Properties of the resulting Yield of of Mn terephthalic acid terephthali based on the ~acid No. reaction Appear- 4CBA Alkaline Ash (percent solution ance content color content on a mole (ppm) (ppm) (ppm) basis) '.' .
Example 7 28 white 290 0.294 4.5 94.2 . . . . . .
Comparative dark Example 6 90 gray 850 ~ 87 94.0 _ _ l .. ~ .
, '"' 1~4ZOl~
Though the terephthalic acid obtained in Comparative Example 6 was hydrogenated and recrystallized9 the dark gray color could not be removed from the terephthallc acid.
Example 8 Into the reactor employed in Example 1 were charged 3.16 gr of cobalt acetate tetrahydrate, 0.0375 gr of manga-nese acetate, 1.026 gr of sodium bromide and 205.8 gr of acetic acid having the water content of 5~0. The proportion - of Co, Mn and Br in the resulting mixture were in the following:
Co proportion 3560 ppm (based on solvent) Mn proportion 40 ppm (based on reaction solution) ~ Br proportion 3600 ppm (based on solvent) :
The pressure in the reactor was raised to 10 Kg/cm2 ~ :
by blowing nitrogen gas into the reactor, and thereafter the temperature of the reactor was raised to 200C, There-. after, 30 gr of p-tolualdehyde was added to the reactor at ~ -;~. 205C at 20 Kg/cm2G over one hour while blowing air into the reactor. After addition of p-tolualdehyde was completed, air was blown into the reactor for another five minutes.
The resulting reaction product was subjected to the same .. ~ treatment as that of Example 1. The yield of the resulting terephthalic acid and the properties thereof are shown in the following Appearance white 4CBA con-tent 210 ppm Alkaline color 0.100 Ash content 3.2 ppm . Yield of tere--. phthalic acid 95.0% on a mole basis ' .- ~
..
, .
- . . .
10~0~4 Example 9 Continuous oxidization of p-tolualdehyde was carried out in an apparatus for continuous oxidization reaction comprising a 2.5 liter pressure reactor made of titanium equipped with refl~x condenser, stirring means, heating means, inlet for raw material, inlet for raw material gas, exit for gas, exit for reaction product, and two receivers for the reaction product connected to the exit for reaction product of the reactor.
Into the reactor were charged 500 gr of acetic acid having a water content of 15%, 1.26 gr of cobalt acetate tetrahydrate, 0.087 gr of manganese acetate tetrahydrate . and 0.515 gr of sodium bromide. The pressure in the reactor : was raised to 10 Kg/cm G, and then the temperature of the reactor was raised to 200C. Feeding solution havlng the ~ -following components was prepared in ~nother container:
. Cobalt acetate tetrahydrate (Co content ~ in the feeding solution 594 ppm) -~ manganese acetate tetrahydrate (Mn -content in the feeding solution 39.1 ppm) sodium bromide (Br content in the feeding solution 805 ppm) The feeding solution was continuously fed into the reactor at the rate of 780 gr/hr, and p-tolualdehyde was continuously fed into the reactor at the rate of 260 gr/hr at 200C at 16.5 Kg/cm2 gauge. At the same time, air was blown into the reactor at such a rate as to maintain the oxygen content in the gas withdrawn from the exit for gas of the reactor at ~%. The reaction product was continuously withdrawn into the receiver so as to keep the level of the ` reaction solution constant.
':`, '", . . . ~ ., 104~0~4 The reaction product in a slurry state was filtered, and cake was separated from the filtrate. The cake was - washed with acetic acid and then water, and was dried to obtain terephthalic acid. The yield of terephthalic acid 5 was 94.4% on the mole basis. The terephthalic acid had the following properties:
Appearance white 4CBA content 184~ ppm Alkaline color 0.801 -~ 10 Ash content 3.3 ppm Mn in the ash based on the acid 1~6 ppm - The resulting terephthalic acid was hydrogenated with molecular hydrogen in the presence of a catalyst and was recrystalli7ed in hot water as disclosed in Japanese Patent : 15 Publication No. 16860/1966. The purified terephthalic acid , had the following properties-J`.'' Appearance white `
4CBA content less than 10 ppm Alkaline color 0.090 ~ 20 The purified terephthalic acid reacted with polyethyl-- ~ ene glycol to form polyethylene terephthalate. The resulting polyethylene terephthalate was clear.
Comparative Example 7 The procedure of Example 9 was repeated except that the feeding solution having Co content of 594 ppm, Mn content of 55.4 ppm and Br content of 805 ppm was used.
The properties of the resulting terephthalic acid ` and the yield thereof were in the followingo Appearance gray 4CBA content 1880 ppm ... .
: . , .
.: 9 .. ..
; .~,.
:, .
10420~4 Alkaline color Ash content 47.4 ppm Mn304 in the ash 35.0 ppm based on the telephthalic - acid - Yield 92.0% on a mole basis The water content in the reaction solution was 16.7%
at the end point of the reaction. Though the resulting terephthalic acid was hydrogenated and was recrystallized ` as disclosed in Japanese Patent Publication No. 16860/1966, ~ the gray color was not removed from the terephthalic acid.
- 10 The purified terephthalic acid reacted with ethylene glycol to form polyethylene terephthalate. However, the resulting polyethylene terephthalate was gray.
' "
. '-' . .
,~ . -; .
'''-.'.' :' ' :', ,' .' ~
:
, " ~
_ 20 -.
. .
. :
Claims (13)
1. A process for producing a non-blackened terephthalic acid from the corresponding para-tolualdehyde which comprises oxidizing the para-tolualdehyde with molecular oxygen or a molecular oxygen-containing gas in a liquid reaction system containing a lower aliphatic monocarboxylic acid as a solvent, and heavy metal salt(s) containing at least one manganese salt, and at least one bromine compound as a catalyst, characterized in that the manganese salt is used in such an amount that the proportion of manganese atom in the reaction system is not more than 40 parts per million by weight based on the combined weight of solvent and water in the reaction system.
2. A process as claimed in claim 1 wherein the manganese salt is used in such an amount that the proportion of manganese atom in the reaction system ranges from 5 ppm to 40 ppm by weight based on the combined weight of solvent and water in the reaction system.
3. A process as claimed in claim 1 wherein the starting material is p-tolualdehyde obtained by reacting toluene with carbon monoxide in the presence of hydrogen fluoride and boron trifluoride as a catalyst.
4. A process as claimed in claim 1 wherein the oxidization reaction is carried out at a temperature ranging from about 120°C to about 240°C.
5. A process as claimed in claim 1 wherein the oxidization reaction is carried out at a pressure ranging from 1 to 50 atoms.
6. A process as claimed in claim 1 wherein the lower ali-phatic monocarboxylic acid is acetic acid.
7. A process for producing a non-blackened terephthalic acid from the corresponding para-tolualdehyde which comprises oxidizing the para-tolualdehyde with molecular oxygen or a molecular oxygen-containing gas in a liquid reaction system containing a lower aliphatic monocarboxylic acid as a solvent, and at least one cobalt salt, at least one manganese salt and at least one bromine compound as a catalyst, characterized in that the manganese salt is used in such an amount that the proportion of manganese atom in the reaction system is not more than 40 parts per million by weight based on the combined weight of solvent and water in the reaction system.
8. A process as claimed in claim 7 wherein the manganese salt is used in such an amount that the proportion of manganese atom is the reaction system ranges from 5 ppm to 40 ppm by weight based on the combined weight of solvent and water in the reaction system.
9. A process as claimed in claim 7 wherein the starting material is p-tolualdehyde obtained by reacting toluene with carbon monoxide in the presence of hydrogen fluoride and boron trifluoride as a catalyst.
10. A process as claimed in claim 7 wherein the oxidization reaction is carried out at a temperature ranging from about 120°C to about 240°C.
11. A process as claimed in claim 7 wherein the oxidization reaction is carried out at a pressure ranging from 1 to 50 atoms.
12. A process as claimed in claim 7 wherein the lower ali-phatic monocarboxylic acid is acetic acid.
13. A process as claimed in claim 7 wherein the cobalt salt is used in such an amount that the proportion of cobalt atom ranges from 100 ppm to 5000 ppm by weight based on the weight of the solvent.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP50019312A JPS5195034A (en) | 1975-02-14 | 1975-02-14 | Futarusanno kokushokukaboshihoho |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1042014A true CA1042014A (en) | 1978-11-07 |
Family
ID=11995885
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA244,541A Expired CA1042014A (en) | 1975-02-14 | 1976-01-29 | Process for producing a non-blackened phthalic acid from the corresponding tolualdehyde |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPS5195034A (en) |
| BE (1) | BE838583A (en) |
| CA (1) | CA1042014A (en) |
| DE (1) | DE2605882C2 (en) |
| FR (1) | FR2300753A1 (en) |
| GB (1) | GB1518901A (en) |
| NL (1) | NL180099C (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5446740A (en) * | 1977-09-20 | 1979-04-12 | Matsuyama Sekyu Kagaku Kk | Manufacture of highly pure terephthalic acid for direct polymerization |
| JPS55145637A (en) * | 1979-05-02 | 1980-11-13 | Teijin Hercules Kk | Preparation of aromatic carboxylic acid or its methyl ester |
| JPH0337579U (en) * | 1989-08-22 | 1991-04-11 |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2154147C3 (en) * | 1970-11-01 | 1978-03-16 | Maruzen Oil Co., Ltd., Osaka (Japan) | Process for the production of terephthalic acid |
| JPS5186437A (en) * | 1975-01-28 | 1976-07-29 | Mitsubishi Gas Chemical Co | FUTARUSANNOKOKUSHOKUKABOSHIHO |
-
1975
- 1975-02-14 JP JP50019312A patent/JPS5195034A/en active Granted
-
1976
- 1976-01-29 CA CA244,541A patent/CA1042014A/en not_active Expired
- 1976-02-06 GB GB477176A patent/GB1518901A/en not_active Expired
- 1976-02-11 NL NL7601392A patent/NL180099C/en not_active IP Right Cessation
- 1976-02-13 DE DE19762605882 patent/DE2605882C2/en not_active Expired
- 1976-02-13 BE BE164339A patent/BE838583A/en not_active IP Right Cessation
- 1976-02-13 FR FR7604022A patent/FR2300753A1/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| NL180099B (en) | 1986-08-01 |
| FR2300753A1 (en) | 1976-09-10 |
| DE2605882C2 (en) | 1983-07-28 |
| JPS5195034A (en) | 1976-08-20 |
| DE2605882A1 (en) | 1976-08-26 |
| FR2300753B1 (en) | 1978-11-10 |
| JPS575777B2 (en) | 1982-02-01 |
| NL180099C (en) | 1987-01-02 |
| NL7601392A (en) | 1976-08-17 |
| BE838583A (en) | 1976-05-28 |
| GB1518901A (en) | 1978-07-26 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4286101A (en) | Process for preparing terephthalic acid | |
| US4594449A (en) | Process for producing terephthalic acid suitable for use in direct polymerization | |
| CA2284721C (en) | Process for preparing 2,6-naphthalenedicarboxylic acid | |
| EP1140765B1 (en) | A production method of aromatic carboxylic acids | |
| US6175038B1 (en) | Method of producing aromatic carboxylic acids by oxidizing alkyl aromatic compounds or partially oxidized intermediates thereof with oxygen-enriched gas | |
| US4241220A (en) | Process for producing terephthalic acid | |
| US4933491A (en) | Method for purifying a crude naphthalene dicarboxylic acid | |
| EP1173401B1 (en) | A production method of aromatic carboxylic acids | |
| US3846487A (en) | Process for the production of fiber grade terephthalic acid | |
| US3171856A (en) | Acid purification process | |
| CA1042014A (en) | Process for producing a non-blackened phthalic acid from the corresponding tolualdehyde | |
| CA1042459A (en) | Process for producing a non-blackened phthalic acid from the corresponding tolualdehyde | |
| US4245078A (en) | Process for producing terephthalic acid | |
| US4824992A (en) | Process for producing pyromellitic acid | |
| US4886906A (en) | Process for producing 2,6-naphthalene dicarboxylic acid | |
| US4214100A (en) | Process for preventing blackening of phthalic acid | |
| JPH01121240A (en) | Production of 2,6-naphthalenedicarboxylic acid | |
| JPS6050775B2 (en) | Continuous production method of terephthalic acid | |
| US4317924A (en) | Process for producing purified terephthalic acid | |
| KR100398160B1 (en) | Process for producing aromatic carboxylic acid | |
| EP1052239B1 (en) | Process for producing pyromellitic acid | |
| JPS5915895B2 (en) | Method for producing aromatic carboxylic acid | |
| KR820000653B1 (en) | Process for preparation of terephthalic acid | |
| US20060205974A1 (en) | Processes for producing aromatic dicarboxylic acids | |
| KR100658609B1 (en) | Process for producing high purity naphthalenedicarboxylic acid |