NL8201387A - PROCESS FOR PREPARING AROMATIC BIS (ETHER-PHTALIC ACID) OR AROMATIC BIS (ETHER-ANHYDRIDE). - Google Patents

Description

S 2348-1172 P & C

Process for preparing aromatic bis (ether phthalic acid) or aromatic bis (ether anhydride).

According to the prior art described in U.S. Pat. Nos. 3,879,428 and 3,957,862, aromatic bis (ether anhydride) nf (hereinafter also referred to as ala "bis anhydrides") according to the general formula (1) of the formula sheet were prepared according to a multi-step process in which an aromatic bis (ether-N-organo-substituted phthalimide) of formula (2) of the formula sheet is subjected to basic hydrolysis; a specific example of these compounds. 2,2-bis [4- (3,4-dicarboxy) phenyl] propane is bis-N-methylimide of the formula i (3) of the formula sheet. In the above formulas, R is a divalent "1 L 10 aromatic group with 6-30" carbon atoms and R is a monovalent organic group, which is an alkyl group with 1-8 carbon atoms or an organic group with 6-20 carbon atoms, for example aromatic hydrocarbon groups and halogenated derivatives thereof. This method provided a salt of a tetraacid, which was then acidified to form the tetraacid, followed by dehydration of the tetraacid to form the aromatic bis (ether anhydride) of formula (1).

Although the process of the above-mentioned US patents provides a valuable pathway for both the aromatic bis (ether-phthalic acids) and the aromatic bis (ether-phthalic anhydrides), this method requires the basic hydrolysis of the aromatic bis (ether- N-organo-substituted phthalimide) of formula (2) and the conversion of the salt formed into the tetraacid, followed by the dehydration of the tetraacid. In addition to requiring a variety of steps to convert the bisimide to a bisanhydride, inorganic salts are formed which cause removal difficulties. Therefore, efforts have been made to provide a simpler process for preparing the bisanhydride of formula (1) or its "precursor", the tetraacid.

U.S. Patent 4,128,574 describes an imide-anhydride exchange reaction leading to the formation of organic polycarboxylic acids, their anhydrides or organic imides. For example, in certain instances, a bisimide of formula (3) is heated with phthalic anhydride in the presence of water to effect an exchange between the above bisimide and the phthalic anhydride to form the corresponding tetraacid or its anhydride.

Although the method of U.S. Pat. No. 4,128,574 overcomes many of the drawbacks of the known methods such as 8201387-2 -f.

to allow easy conversion of N-alkyl substituted bisimides and the direct formation of cyclic anhydrides, as well as eliminating the formation of inorganic salts or the requirement of a multi-step process, the process is as follows U.S. Patent 4,128,574 is essentially a discontinuous method. The obtaining of a tetraacid or bisanhydride in a satisfactory yield, 80% or more, requires various heating and stripping treatments. It is also difficult to achieve significant conversion of the bisimide to the tetraacid or bisanhydride without recourse to recycling of very large amounts of phthalic acid or phthalic anhydride. Due to the nature of the exchange between the bisimide and phthalic acid or phthalic anhydride, optimal conversion cannot be achieved unless the N-organo-phthalimide of the general formula (4) of the formula sheet, wherein R * has the definition given above, which compound is also formed during the reaction, separated from the mixture.

US Pat. No. 4,116,980 shows that optimal conversion of the bisimide to its tetraacid or dianhydride can be achieved by the imide anhydride exchange in the presence of water, which exchange can be represented as follows: A + B A '+ B', wherein A and A 'represent imides and B and B' anhydrides, if the imide A 'is selectively removed from the reaction mixture during the exchange. For example, in the above equation, A may be a bisimide, B is a phthalic acid, B 'is a bis-anhydride or tetraacid, and A' is an N-organophthalimide. These results were obtained according to the aforementioned U.S. Patent 4,116,980 by discharging part of the vapor phase of the reaction mixture, which consists of a liquid phase and a vapor phase, during the exchange. The vapor phase mainly consists of water and N-organo-phthalimides and very little phthalic acid, so that by continuously discharging the vapor phase during the exchange the reaction is driven to the right. It is therefore possible to convert the bisimide used as starting material to the corresponding tetraacid or bisanhydride without shutting down the reactor or recycling very large amounts of phthalic acid.

The invention is based on the development of a new method for the two-phase imide-anhydride exchange, in which a solution of an aromatic bis (ether-N-organo-substituted phthalimide), hereinafter also referred to as "B1", in an inert organic solvent is contacted at an elevated 8201387 t-3 temperature with an aqueous solution of phthalic acid, also referred to herein as "PA" and an exchange catalyst. Imide-anhydride exchange takes place and a major part of the bis compound migrates from the organic phase to the aqueous phase, where this compound is present as the salt of the aromatic bis (ether-phthalic acid) of the general formula (5 ) of the formula sheet (also referred to herein as "TA"), in which formula R has the definition given above. This compound can be easily converted to the aromatic bis (ether-phthalic anhydride) of formula (1) by conventional means (herein also referred to as "DA"). The N-organo-phthalimide formed by the exchange (also referred to herein as "PI") migrates from the aqueous phase j to the organic phase, favoring increased conversion of PI to TA. Unreacted "excess" phthalic acid remains as salt in the aqueous phase.

Before the exchange reaction, all imides (PI and B1) are in the organic phase and all acids and the catalyst are in the aqueous phase.

After the exchange reaction, when an equilibrium has established, most of the PI has migrated from the organic phase to the aqueous phase where it is present as the salt of TA. The phthalimide PI formed by the exchange migrates to the organic phase, together with the unreacted B1 and some aromatic bis (ether-N-organo substituted phthalimide ether anhydride) (hereinafter also referred to as "IA") with the general formula (6) of the formula sheet, wherein R and R 'have the definitions given above. At equilibrium, therefore, the original state still exists, with all imides in the organic phase and all acids or salts of the acids in the aqueous phase, apart from a small amount of IA present in both phases.

Corrosion problems arising in the known methods can be practically eliminated by neutralizing all acids by using an amine as a catalyst, and further, the two-phase exchange allows complete separation of the N-organophthalimide from the phthalic acid. The exchange can also be greatly accelerated by catalysis and requires considerably less energy than the known methods, while retaining reactants, solvents and catalyst.

The invention provides a process for the two-phase imide-anhydride exchange, for preparing aromatic bis (ether-phthalic acid) from aromatic bis (ether-phthalimide), comprising: (A) a mixture containing (i) aromatic bis (ether-phthalimide) of formula (2), (ii) 2-20 moles of phthalic anhydride or phthalic acid per mole (i), 8201387 W * - 4 - (iii) a sufficient and effective amount of an exchange catalyst (iv) 0.01 - 100 parts by weight of water per part by weight (i) and (v) 0.01 - 100 parts by weight of an inert immiscible organic solvent per water part by weight (i) on an elevated temperature, for example, 170 ° - 260 ° C and under superatmospheric pressure, for example, about 1380 - 3450 kPa, is heated to form an equilibrated two-phase liquid reaction mixture, an aqueous phase in which the aromatic bis (ether-phthalic acid), the exchange catalyst and optionally unreacted phthalic acid formed in the exchange reaction are selectively dissolved, and an organic phase in which the N-organo substituted phthalimide of formula (4) also formed in the exchange reaction and optionally unreacted aromatic bis (ether-phthalimide) are selectively dissolved, (B) the organic phase of the aqueous phase, and (C) isolates the aromatic bis (ether-phthalic acid) from the aqueous phase.

Examples of groups represented by the symbol R are those of the formulas (7), (8), X9), (10), (11), (12), (13) and divalent organic groups according to the general formula (14), where X is a group -C ^ E ^ - (where y is an integer value 1 - 5), —C (0) -, -SO -, -O-, or -S- and m has the value 0 or 1.

* 1 Examples of groups represented by R are phenyl, tolyl, xylyl, naphthyl, chlorophenol, bromine naphthyl, etc., and alkyl groups such as methyl, ethyl, propyl, etc.

The bisimides of formula (2) as well as a process for their preparation are described in the aforementioned U.S. Pat. No. 3,883,428; this process is based on the initial formation of N-organo-substituted phthalimide of the formula (15) of the formula sheet, wherein X is a nitro group or a halogen atom (e.g. chlorine, fluorine, bromine, etc.) and R has the definition given above . The phthalimide of formula (15) can be formed by effecting a conversion between an X-substituted phthalic anhydride and an organic amine, such as aniline, toluidine, methylamine, ethylamine, etc.

Examples of phthalimides of formula (15) are N-methyl-4-nitrophthalimide, N-phenyl-3-nitrophthalimide, N-phenyl-4-nitrophalimide, N-methyl-3-nitrophthalimide, N-butyl-4-nitrophthalimide, etc. As further disclosed in U.S. Pat. wherein R has the definition given above and M is an alkali metal ion, for example sodium, potassium, lithium, 8201387 1 * - 5 - etc.

Examples of the alkali metal diphenoxides of formula (16) are the sodium and potassium salts of the following divalent phenols: 2,2-bis (2-hydroxyphenyl) propane; 2,4'-dihydroxydiphenylmethane; bis- (2-hydroxyphenyl) methane; 2,2-bis- (4-hydroxyphenyl) propane, hereinafter also referred to as "Bisphenol-A" or "BFA", 1,1-bis- (4-hydroxyphenyl) ethane; 1,1-bis- (4-hydroxyphenyl) propane; 2.2-bis- (4-hydroxyphenyl) pentane; 3.3-bis- (4-hydroxyphenyl) pentane; 4,4'-dihydroxybiphenyl; 4,4'-dihydroxy-3,3,5,5 '-tetramethy 1b.if eny 1; 2,4'-dihydroxybenzophenone; 4,4'-dihydroxydiphenylsulfone? 2,4'-dihydroxydiphenyl sulfone; 4,4'-dihydroxydiphenyl sulfoxide; 2,4'-dihydroxydiphenyl sulfoxide; 4,4'-dihydroxydiphenyl sulfide; hydroquinone; resorcinol; 3,4'-dihydroxydiphenylmethane; 4.4 * dihydroxybenzophenone; 4,4'-dihydroxydiphenyl ether, etc.

Exchange catalysts which can be used according to the invention are: acids such as sulfuric acid, phosphoric acid, hydrochloric acid, methanesulfonic acid, fluoroboric acid, toluenesulfonic acid, acetic acid, butyric acid, trifluoroacetic acid, etc. metal salts, such as FeGl 2, ZnCl 2, SnCl 4, AlCl 2 and 30 de corresponding bromides; trialkylamines (hereinafter also referred to herein as) such as trimethylamine, triethylamine, tripropylamine, tributyl, amine, etc., the preferred catalysts being triethylamine and trimethylamine.

Organic solvents which can be used according to the invention are inert water immiscible solvents which selectively dissolve any imide compound initially present or formed during the reaction, for example toluene, benzene, xylene, chlorobenzene and orthodichlorobenzene.

The following general and preferred parameters are 82 0 1 3 8 7 1 J «- 6 - determined for the two-phase imide anhydride exchange method:

1. Temperature Range 170 ° -260 ° C

Preferred 185 ° -225 ° C

2. Pressure Determined by temperature 5 Range approx. 1380-3450 kPa 3. PA: BI molar ratio Range 2: 1 to 20: 1

Preferred 4-6: 1 4. Catalyst molar ratio, PA Range 1: 1 to 3: 1

Preference „2: 1 10 5. Weight ratio organic Range 0.1 to 10: 1 solvent: water Preference> 4: 1 6. Solid content Range 1% to 70 $

Preference „10-15%

The invention is further elucidated with reference to the annexed drawing.

Fig. 1 shows a continuous, three-step imide anhydride exchange process according to the present process, wherein 2,2-bis 4- (3,4-dicarboxyphenoxy) phenylpropane having a purity of at least 97 mol% is obtained by an imide to effect anhydride exchange between PA and B1 in the presence of an organic solvent that selectively absorbs the imide, separating and removing the organic phase, then repeating the equilibration and separation with organic solvent two more times to form TA in the aqueous phase. The organic phase is used in the third, second and then first equilibrium separation step, after which it is distilled to remove the imides and recycled to the third equilibrium step and recycled. PI is isolated from the imides removed during the distillation and this compound can be nitrated and used to prepare more B1, while residual B1 and IA are recycled. After isolation of the TA from the aqueous phase by distillation of E 2 O, R N and unreacted. PA, these materials are recycled to the first equilibrium step.

In Figure 1, 10 is the first equilibrium vessel, in which an aqueous solution of excess PA and 2 moles R 2 N as catalyst per mole PA are heated together with a solution of PI in toluene. Phthalic acid (PA) or phthalic anhydride is passed through line 3 from a PA reservoir 2 along with recycled water, R 2 N and any unreacted PA from the previous cycle through line 12 to 10. Toluene from step 2 of the previous cycle is recycled through line 13. The starting material 40 B1 is passed from reservoir 1 through line 11 to the first equilibrium vessel 10, together with unconverted. B1 and partially converted IA, which are separated from the toluene in distillers 4 and 6 and transported through lines 5 and 8. The two phases are heated together for about 1-2 hours at about 200 ° C at a pressure of about 2070 -3450 kPa, depending on the temperature used, to obtain a mixture which is chemically equilibrated.

At this point it becomes. mixture from equilibrium vessel 10 is pumped through line 14 to the first phase separator or decanter 20. While the mixture is still hot, it is allowed to "settle" and separate; the toluene phase is discharged and pumped through line 22 to a first distillation unit 4 in which the toluene is removed by evaporation and condensed to then be recycled. The bottom fraction from distiller 4, containing BI, IA and PI, is pumped through line 5 to a second distillation unit 5, where BI is distilled off and, if necessary, subsequently prepares BI. The bottom fraction from distiller 15, containing B1 and IA, is recycled through line 8 to the first equilibrium vessel 10. The aqueous phase from the first phase separator 20 is pumped through line 21 to a second equilibrium vessel 30, where this phase is mixed with toluene from the third phase separator 50. When equilibrium 20 is reached in the second equilibrium vessel 3Q, the mixture is pumped through line 31 to the second phase separator 40, from. from which - after "settling" - the toluene layer is returned to the first equilibrium vessel IQ through line 13; the aqueous phase is pumped through line 41 to the third equilibrium vessel 5Q. Toluene from distiller 4 is passed through line 52 to the third equilibrium vessel ~ 50. pumped and the mixture is injected again. equilibrated and pumped to the final phase separator or decanter 60. The toluene layer from 6Q is passed through line 32 to the second equilibrium vessel 30, and the aqueous phase through line 6.1 to a third distiller 70 in which PA, E 2 O and R 2 N are distilled, condensed and passed through line 12 to the first, weight vessel 10 is returned. The bottom fraction from distiller 70 is removed to obtain DA.

The following non-limiting examples further illustrate the invention.

Each of the 9 balancing steps (balancing) were performed discontinuously as described below. The toluene phases were treated in the manner shown in Figure 2, which figure speaks for itself.

8201387 - 8 -

EXAMPLE I

Into a 1 L autoclave, 35.7 g (0.24 mole) of phthalic anhydride, 21.84 g (0.04 mole) of the bisimide of formula (3) were introduced, hereinafter also referred to as " BFA-B1, 67 ml (0.48 mol) triethylamine, 80 ml water and 320 ml toluene. The autoclave was rinsed with N2, sealed and heated at 200 ° C for 2 hours. The autoclave was then cooled and opened. The organic phase and the aqueous phase were separated and samples were taken from both phases. The aqueous phase was returned to the autoclave along with the following amount of toluene 10 as shown in Fig. 2. The autoclave was rinsed again with N2, sealed and heated again at 200 ° C for 2 hours. The further processing described for the first equilibrium step was repeated.

The samples of both phases from each cycle were freed from solvent under reduced pressure (~ 25 mm Hg) and at 200 ° C and analyzed by liquid chromatography (Waters Associates LC, corisol-I, column of about 0.32 cm x about 5 , 1 cm, solvent: 40% CE ^ Cl ^, 59.5% CHCl ^ and 0.5% Et 2 O; flow rate: 2 ml / min, detector: UV, λ 254). The results are shown in the table below; the amounts of the components in the aqueous phase are given in mol%.

20 TABLE A

Composition of the amide anhydride exchange product (Mol%)

CYCLE I

Balancing step BI IA TA

25 1 0.02 15.2 84.8 2 0.02 1.8 98.2 3 0.02 0.6 99.4

-icbtCou-. ·· CYCLE II

Balancing step Bi IA TA

30 1 0.02 6.0 84.0 2 0.02 2.4 97.6 3 0.02 0.4 99.6

CYCLE III

Balancing step BI IA TA

35 1 0.02 11.2 88.8 2 0.02 2.4 97.6 3 0.02 0.5 99.5

From the above results, it appears that a two phase exchange reaction is able to provide a product having at least about 8201387 V * - 9 - 85 mol% TA after only one equilibration step. Two and three steps led to resp. about 98 and about 99.5 mol% product.

In all three cycles, the third equilibrium step gave about 18 g (0.035 mol) TA of more than 99 mol%, which corresponds to a total conversion of 5 B1 of formula (2) into TA of formula (5) of about 86%, the latter compound being readily dehydrated to DA of formula (1).

DETAILED DESCRIPTION OF A CONTINUOUS PROCESS The invention also includes a two-phase continuous imide-anhydride exchange process involving the solution of an aromatic bis (ether-N-organo substituted phthalimide) (hereinafter also referred to as "B1") is contacted in an inert organic solvent with the aqueous solution of phthalic acid (also referred to herein as "PA") and an elevated temperature exchange catalyst in a heated reactor in the form of a tubular coil. Imide anhydride exchange takes place and a major part of the bis compound migrates from the organic phase to the aqueous phase where it is present as the salt of the aromatic bis (ether-phthalic acid) (hereinafter also referred to as "TA"). ") with the general formula (5). The elevated temperature and pressure required for the imide anhydride exchange reaction can be easily achieved in the laboratory by using simple autoclaves.

However, on an industrial scale, such heavy wall pressure equipment becomes very expensive. Furthermore, stirring the contents of the autoclave, which would promote a shorter reaction time, is very difficult since this type of device with moving parts and high pressure seals around rotating shafts is very difficult to maintain. For the; equilibrium with the two-phase system of the invention is very important. Mixing can be accomplished by passing the two-phase mixture through a tubular coil held horizontally. Due to density differences, the organic phase rises through the aqueous phase in the ascending part of the spiral and the aqueous phase decreases through the organic phase in the descending part of the spiral. The process continues along the length of the coil and provides good contact between the two phases, thus accelerating the balancing process.

The invention therefore provides a continuous two-phase imide-anhydride exchange process for preparing aromatic bis (ether-phthalic acid) from aromatic bis (ether-phthalimide), by which method: (A) a mixture containing (i) aromatic bis (ether-phthalimide) according to 8201387-10 - formula (2), (ii) 2-20 moles of phthalic anhydride or phthalic acid per mole (i) / (iii) .a sufficient and effective amount of an exchange catalyst, (iv 0.01 - 100 parts by weight of water per part by weight (i) and (v) 0.01 - 100 parts by weight of a water-immiscible inert organic solvent per part by weight (i), 5 at elevated temperature, for example 170-260 ° C, and under superatmospheric pressure, for example about 1380 - 4850 kPa, passes through a heated reactor in the form of a tubular coil, to form an equilibrated two-phase liquid reaction mixture exists, namely an aqueous phase in which the aromatic bis (eth erphthalic acid), the exchange catalyst and any unreacted phthalic acid are selectively dissolved, and an organic phase in which N-organo substituted phthalimide of formula (4), which is also formed in the exchange reaction, and optionally unreacted aromatic bis (ether phthalimide) are selectively dissolved, (B) separates the organic phase from the aqueous phase, and (C) isolates the aromatic bis (ether-phthalic acid) from the aqueous phase.

The tubular spiral reactor of this embodiment can be made of any tubular material that can withstand the temperatures and pressures of the reaction and is not affected by the reaction mixture of the two-phase process. Examples of tubular materials that can be used are stainless steel 316, stainless steel 347, glass, etc.

The length of the tube (1), the cross-section of the tube (a) and the flow rate (r) determine the rate of the exchange reaction and therefore the residence time (t) required to approach equilibrium.

These parameters are related as follows: la / r = t. Kinetic research showed that a residence time of approximately 2 hours was required.

The tubular spiral reactor is heated, for example, by an oil-filled heating jacket or by other suitable means.

For the two-phase continuous imide anhydride exchange carried out in a hot tubular reactor, the following general and preferred parameters were determined: 8201387 - 11 -

1. Temperature Range 170 ° - 260 ° C

Preferred 185 - 225 ° C

2. Pressure Determined by temperature

Range 200 - 700 psi 5 3. Molar ratio PA: BI Range 2: 1 to 20: 1

Preferred 5-6: 1 4. Catalyst molar ratio: PA Range 1: 1 to 3: 1

Preference “2: 1 5. Weight ratio Range 0: 1 to 10: 1 10” solvent: water Preference “4: 1 6. Solid content Range 1% to 60%

Preference "10 - 15% 7" PA concentration in Range 0/2 - 6 mol / liter aqueous phase Preference «. 3 mol / liter 15 8. CI concentration in Range 0.02 - 1 mol / liter organic phase Preferred „0.2 mol / liter

In the continuous process, an aqueous solution containing PA and Λ Λ an exchange catalyst and an organic solution containing the BI are combined and fed into the reactor in the form of a tubular coil under pressure. Generally, heating of both phases participating in the reaction is required to maintain high concentration reactant solutions. After passing through the reactor, the phases are separated in the usual manner; the solvents, reaction components and catalysts are distilled off to be optionally recycled. The PI obtained from the organic phase can be nitrated and used to prepare more BI. The TA present as product in the aqueous phase gives DA after dehydration.

EXAMPLE II

A hot tubular reactor of 7.62 m and an internal diameter of 10.9 mm was used, which reactor was made of a tube of stainless steel 347 with a volume of 640 cm, which was formed into a multi-winding spiral (helix) with a diameter of 16 cm, which was arranged horizontally. The reactor was surrounded by a copper jacket and heated to 200 ° C with flowing hot oil. The pressure in the. reactor was maintained at about 3450 kPa to avoid boiling of the contents.

An aqueous solution of 2.98 mol PA / liter and 4.5 mol triethylamine (catalyst) / liter was heated to 65 ° C to prevent crystallization at a rate of 3 ml / min. punched to the hot tubular reactor 40.

A solution of B1 in toluene (0.22 mol / liter) was heated at 80 ° C. 8201387-12 at a rate of 7 ml / min. pumped to the hot tubular reactor. These flow rates result in a molar ratio between PA and B1 of 5.75: 1.

Total operating time was about 6 hours and total flow rate was 10 ml / min .; samples were taken every 6 minutes after the calculated residence time,

The reactor was first charged with aqueous PA solution.

The samples from both phases were freed from solvent under reduced pressure (about 25 mm Hg) and at 200 ° C, and analyzed by liquid chromatography (Waters Associates LC, corisol-I column about 0.32 cm x about 5.1) cm, solvent: 40% CH2 Cl2, 59.5% CHCl2 and 0.5% Et2 O; flow rate: 2 ml / min, detector: UV, 254).

The results are shown in Table B below, in which table the concentration of the bis compounds (B1 + IA + TA) in grams per liter and the concentration of TA in the bis compounds in mol% are given.

The data shows that a "steady state" or equilibrium after approx. 120 minutes had been reached and no further mass from the organic phase thereafter. transferred and the mole percentage TA remained unchanged, namely approximately 75%.

20 TABLE B

Composition of the imide anhydride exchange product from the heated tubular spiral reactor 1)

Bis compounds Mol% TA

Time (minutes) __g / liter in bis compounds 25 39 8.99 43 50 33.33 70 60 87.66 83 72 119.33 81 81 146.33 79 30 93 163.33 76 105 170.66 75 120 182 , 00 85 135 184.03 · 77 152 186.60 74 35 170 188.00 74 189 186.66 74 205 183.30 75

1) bis compounds = B1 + IA + TA

The above results show that a two-phase continuous exchange reaction conducted in a tubular coil hot reactor, after one pass through the reactor, is capable of providing a product with at least about 75 mole% TA . The product from the first pass was recycled through the 8201387-13 reactor under the same conditions, except that the toluene contained no B1. This resulted in a product with about 95 mol% TA. A third pass, again with only organic phase toluene, gave a product containing at least. 87 mol% TA.

EXAMPLE III

Initial conditions and concentrations were the same as in Example I; however, the flow rates for the aqueous phase and the organic phase were both 5 ml / min. This leads to a mole ratio between PA and B1 of 13.42: 1.

The results are given in Table C below.

TABLE C

Composition of product from heated tubular spiral reactor

Bis compound Mol% TA in

Time (minutes) Concentration g / liter bis compounds 15 56 67.6 88 68 94.9 88 81 100.0 88 93 102.0 88 105 104.0 88 20 116 100.6 88 128 100.3 88 141 101 , 1 88

These data show that after about 81 minutes a "steady state" was reached and a product with about 88 mol% TA 25 was obtained. The shorter time to reach equilibrium, namely 81 minutes to 120 minutes in Example II, and, the higher mole percentage TA, namely 88% to 77% in Example II, are due to the greater mole ratio between PA and B1, namely, 13.42: 1 against 5.75: 1 in Example II.

8201387

Claims (19)

A process for the two-phase imide-anhydride exchange, for preparing aromatic bis (ether-phthalic acid) of formula (5) or its anhydride, characterized in that: 5 (A) is a mixture containing: ( i) aromatic bis (ether-phthalimide) of formula (2), (ii) phthalic anhydride or phthalic acid, (iii) an exchange catalyst, (iv) water and (v) a water-immiscible, inert organic solvent heated under obtaining an equilibrium liquid reaction mixture consisting of two phases, an aqueous phase in which the aromatic bis (ether-phthalic acid) formed in the exchange reaction, the catalyst and any excess phthalic acid are selectively dissolved, and an organic phase in which N-organo-substituted phthalimide of formula (4), which compound is also formed in the exchange reaction, and optionally unreacted aromatic bis-15 (ether-phthalimide) are selectively dissolved, (B) the organic separates the phase from the aqueous phase, (C) isolates the aromatic bis (ether-phthalic acid) from the aqueous phase, and optionally dehydrates this compound to form the di-anhydride, wherein in the above formulas R a divalent aromatic 20 represents a group of 6-30 carbon atoms and R represents a monovalent organic group, namely an alkyl group of 1-8 carbon atoms or an aromatic hydrocarbon group of 6-20 carbon atoms or a halogenated derivative thereof. 2. Process according to claim 1, characterized in that a reaction temperature of about 170 ° - 260 ° C and a reaction pressure of about 1380 - 3540 kPa is used. A method according to claim 1 or 2, characterized in that the phthalic acid is present in an amount of about 2-20 moles of the anhydride per mole of aromatic bis (ether-phthalimide). 4. Process according to claims 1-3, characterized in that a trialkylamine is used as the exchange catalyst. Process according to claim 4, characterized in that triethylamine is used as the exchange catalyst. 6. Process according to claims 1-5, characterized in that the catalyst is present in a molar ratio of about 1-3 moles of catalyst to 1 mole of bis (imide). Process according to claims 1-6, characterized in that about 0.01 - 100 parts by weight of water per part by weight of bis (imide) are used. 8. Process according to claims 1-7, characterized in that toluene is used as 8201387 - c - IS '- organic solvent. 9. Process according to claims 1-8, characterized in that an amount of solvent of 0.01-100 parts by weight per part by weight of bis (imide) is used. 10. Process according to claims 1-9, characterized in that R 1 is a methyl group. 11. A method according to claims 1-10. characterized in that the aromatic bis (ether-phthalic acid) is 2,2-bis (4- (3,4-dicarboxyphenoxy) phenyl] propane. 12. Process according to claims 1-11, characterized in that the bis- (ether-N-organo-substituted phthalimide 2,2-bis [4- (3,4-dicarboxyphenoxy) -phenyl] propane-bis-N- methyllmide is ·. 13. Process for the two-phase imide-anhydride exchange, for preparing aromatic bis (ether-phthalic acid) of formula (5) or its anhydride from aromatic bis (ether-phthalimide), characterized in that : (A) a mixture containing (i) aromatic bis (ether-phthalimide) of formula (2), (ii) 2-20 moles of phthalic anhydride or phthalic acid per mole (i), (iii) 1-3 moles of a trialkylamine exchange catalyst per mole (i), (iv) 0.01-100 parts by weight of water per part by weight (i) and (v) 0.01-10% by weight of 20 parts with water. miscible organic solvent per part (i) at a temperature of 170 ° - 260 * 0 and at a pressure. of about 1380. - 3450 kPa, to form an equilibrium two-phase liquid reaction mixture, an aqueous phase in which the aromatic bis (ether-phthalic acid) formed in the exchange reaction, the trialkylamine (catalyst) and any excess phthalic acid are selectively dissolved, and an organic phase in which N-organo-substituted phthalimide of formula (15), which is also formed in the exchange reaction, and optionally unreacted aromatic bis (ether phthalimide) are selectively dissolved, (B) separates the organic phase from the aqueous phase, and (C) isolates the aromatic bis (ether-phthalic acid) uxt the aqueous phase, in which formulas R a divalent aromatic group having 6- 30 carbon atoms, R represents a monovalent organic group, namely an alkyl group of 1-8 carbon atoms or an aromatic hydrocarbon group of 6-20 carbon atoms or eeh: halogenated derivative thereof, and X a nit ray group or halogen atom (fluorine, bromine, etc.). Method according to claims 1-13, characterized in that a number of equilibrium and phase separation steps are used. Process according to claim 14, characterized in that the reaction components, catalyst, and the solvents are continuously recycled and retained. 16. Process according to claims 1 to 13, characterized in that the process is carried out continuously by passing the mixture mentioned under (A1) through a heated reactor in the form of a tubular spiral. Method according to claim 16, characterized in that the reaction temperature is about 170 ° - 260 ° C and the reaction pressure is about 1380 - 4825 kPa. 18. Process according to claim JL6 for preparing aromatic bis-10 (ether-phthalic acid) of formula (5) 'or its anhydride from aromatic bis (ether-phthalimide), characterized in that: (A) a mixture, containing (i) aromatic, bis (ether-phthalimide). according to formula (2), (ii) 2-20 moles of phthalic anhydride or phthalic acid per mole (i), (iii) 1-3 moles of a trialkylamine as an exchange catalyst per mole of 15 (i), (iv) 0.01 - 100 parts by weight of water per wt. parts (i) and (v) 0.01 - 100 parts by weight of a water-immiscible organic solvent per part (i), at 170 ° - 260 ° C and a pressure of about 1380 - 4825 kPa by conducts a reactor in the form of a tubular spiral, to obtain a balanced two-phase liquid reaction mixture, namely an aqueous phase in which the aromatic bis (ether-phthalic acid) formed in the exchange reaction, the trialkylamine ( catalyst) as well as any excess phthalic acid are selectively dissolved, and an organic phase in which N-organo-substituted phthalimide of formula (4), which is also formed in the exchange reaction, and optionally unreacted aromatic bis (ether-phthalimide) are selective dissolved, (B) separates the organic phase from the aqueous phase, and (C) isolates the aromatic bis (ether-phthalic acid) from the aqueous phase, in which formulas R represents a divalent aromatic group containing 6-30 carbon atoms , and R a ee valuable organic group, namely an alkyl-30 group with 1-8 carbon atoms or an aromatic hydrocarbon group with 6-20 carbon atoms or a halogenated derivative thereof. Process according to claim 18, characterized in that the reactants, the catalyst and solvents are recycled continuously. 8201387