RU2388768C2 - Polyether-ketone synthesis method - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a method for synthesis of aromatic polyether-ketones through a nucleophilic substitution reaction in aprotonic dipolar solvents (ADS) which takes place when 2,2-bis(4-hydroxyphenyl)propane (diane) diphenolate reacts with dihalogenbenzophenol in an aprotonic diplar solvent. The method involves synthesis of polyether-ketone in anhydrous dimethylsulphoxide takes place in two steps, at the first step through reaction of diane with 4,4'-dichlorobenzophenone (molar ratio 1: 0.5) concentration of the solution C=1 mol/l of diane for 1 hour after azeotropic distillation of water at temperature 185°C in the presence of solid powdered KOH, potassium diphenolate dimer with diphenoxide anion structure -O-C₆H₄-C(CH₃)₂-C₆H₄-O-C₆H₄-CO-C₆H₄-O-C₆H₄-C(CH₃)₂-C₆H₄-O- is obtained, at the second oligo-polymer step a mixture of 4,4'-difluorobenzophenone and 4,4'-dichlorobenzophenone is added with annealing and grinding K₂CO₃ (molar ratio diane: 4,4'-difluorobenzophenone : 4,4'-dichlorobenzophenone : K₂CO₃=1:0.5:0.005:0.15) in anhydrous dimethylsulphoxide. Optimum concentration of the reaction mixture at the said step is 0.5 mol/l in terms of diane and the reaction take place in 6-7 hours.

EFFECT: method enables optimisation, intensification and significantly lower the cost of obtaining polyarylene ether ketones (PAEK) by replacing dimethylacetamide with dimethylsulphoxide and half of 4,4'-difluorobenzophenone required for the reaction with 4,4'-dichlorobenzophenone.

Description

The invention relates to a method for producing simple aromatic polyetherketones by nucleophilic substitution in aprotic dipolar solvents (ADPR). The reaction proceeds during the interaction of bisphenol diphenolates with dihalogenbenzophenones.

Polyarylene ether ketones (PAEC) are high molecular weight compounds with a range of valuable properties (high heat, thermal, chemoresistance, unique physical and mechanical characteristics, and solubility in a number of organic solvents), which allows the use of these polymers as superstructural polymer materials in various industries industrial production [PTMcGrail Polyaromatics. // Polymer International. - 1996.- V.41. - P.103].

Known methods for the synthesis of PAEC by a nucleophilic substitution reaction proceeding according to the scheme:

2nMe ⁺ + n ^- O-Ar-O ^- + nX-Ar ₁ -X → - [O-Ar-O-Ar ₁ -] _n + 2n MeX,

where Ar are aryl radicals of various chemical structures; Me = Na, K; X = F, Cl; Ar ₁ = C ₆ H ₄ —CO — C ₆ H ₄ .

The reaction can be carried out in a melt or in a solution of ADPR; Each of these methods has its advantages and disadvantages.

The nonequilibrium nucleophilic polycondensation of PAEC in ADPR at elevated temperatures is widespread in industrial production, because when carrying out the process in the melt, it is much more difficult to control the degree of completion of the reaction due to local overheating of the viscous reaction mass, which leads to a large spread in molecular masses.

It is known that the process of producing simple aromatic polyesters in ADPR can be carried out in one or two stages, in a homogeneous or heterogeneous medium (in case of poor solubility of diphenolate), while different ADPRs (dimethyl sulfoxide, dimethylacetamide, sulfolane, etc.) and various catalytic superbased "environments.

As a catalytic "superbasic" medium, various ratios and combinations of ADPR with hydroxides, bicarbonates, carbonates, fluorides, alkali metal sulfides in combination with Al ₂ O ₃ or SiO _{2 are} proposed in the patent literature [RF Patent 2063404, IPC C08G 65/40, 75 / 40. A method of obtaining aromatic polyesters. / Bolotina L.M., Chebotarev V.P.].

The closest to the achieved effect is the method for producing aromatic simple polyetherketones in dimethylacetamide (DMAA), described in the article [Shaposhnikova V.V., Salazkin S.N., Sergeev V.A., Blagodatskikh I.V. et al. "Regularities of the reaction of 4,4'-difluorobenzophenone with potassium diphenolate 2,2-bis (4-hydroxyphenyl) propane" - Bulletin of the Academy of Sciences, chemical series, 1996. - No. 10].

The authors studied the laws of this reaction in DMAA (influence of temperature, reaction time, concentration of starting monomers, molar ratio of 2,2-bis (4-hydroxyphenyl) propane (dian): K ₂ CO ₃ , dian: 4,4'-difluorobenzophenone ) The best results were obtained with the so-called one-stage process (all starting materials are loaded, azeotropic distillation of water and the polycondensation process occur simultaneously), the concentration of diane is 0.5 mol / l, the ratio of diane: K ₂ CO ₃ = 1: 1.3 (mol ) with 0.005 (mol) excess of 4,4'-difluorobenzophenone, the duration of heating after completion of azeotropic distillation of water was 6-10 hours at a temperature of 185 ° C.

It was found in the work that the complete replacement of 4,4'-difluorobenzophenone with a cheaper but less active 4,4'-dichlorobenzophenone does not make it possible to obtain a polymer in DMAA (t _bp = 165.5 ° C) with a high molecular weight at a temperature 185 ° C even with an increase in the reaction time by 3 times (i.e., the reaction was carried out at the same temperature for 30 hours).

Disadvantages of the prototype are the high cost of polyarylene ether-based expensive 4,4'-difluorobenzophenone, and conducting the reaction in dimethylacetamide, which is more expensive and more toxic than dimethylsulfoxide, dimethylacetamide and the boiling temperature (t _refluxing = 165,5 ° C) lower than the temperature of the reaction indicated in the prototype, which increases the fire hazard and does not make it possible to reach 185 ° C in the reaction mixture without violating the optimal synthesis conditions.

The objective of the invention is the intensification, optimization and cheapening of the process of producing polyarylene ether ketone (PAEC) based on diane and dihalogenobenzophenones (4,4'-dichloro and 4,4'-difluorobenzophenones) while preserving the physical and mechanical characteristics inherent in this polymer.

The method consists in the fact that the reaction of the interaction of potassium diphenolate of diane with dihalogenobenzophenones in dimethyl sulfoxide (DMSO) (t _bale = 89 ° C) is carried out as a continuous process in two stages.

At the first stage of the process, from diane and carbon-free KOH (molar ratio 1: 2) we obtain a solution of potassium diphenolate diane in anhydrous DMSO. Next, we carry out the condensation reaction of diane diphenolate with 4,4'-dichlorobenzophenone (molar ratio 1: 0.5), the concentration of the solution on diane is 1 mol / L. After azeotropic distillation of water, the reaction is completed in 1 hour at 185 ° C, and a diphenolate dimer is formed, the structure of the diphenoxide anion of which:

^- O-C ₆ H ₄ -C (CH ₃ ) ₂ -C ₆ H ₄ -O-C ₆ H ₄ -CO-C ₆ H ₄ -O-C ₆ H ₄ -C (CH ₃ ) ₂ -C ₆ H ₄ -O ^- .

At the second stage of the process, a mixture of crushed and calcined K ₂ CO ₃ (or Na ₂ CO ₃ ), 4,4'-difluorobenzophenone and 4,4'-dichlorobenzophenone in molar ratios of 0.15: 0.5: 0.005 per 1 mol of the initial mixture is added diana, in anhydrous DMSO (the volume of DMSO is taken from the calculation that the concentration of the solution at the second oligo-polymer stage of synthesis will become equal to 0.5 mol / L). Thus, the total molar ratio of diane, KOH, K ₂ CO ₃ (or Na ₂ CO ₃ ) and a mixture of 4,4'-difluoro- and 4,4'-dichlorobenzophenone in the sum of two stages was 1: 2: 0.15: 1.005. The formation of PAEC after azeotropic distillation of water is 6 hours.

The method is illustrated by the following examples.

Example 1. The synthesis was carried out in a four-necked flask previously purged with dried and oxygen-free nitrogen (argon), equipped with a stirrer, thermometer, nitrogen supply tube and Dean-Stark nozzle for azeotropic distillation of water. 5.7073 g (0.025 mol) of 2,2-bis (4-hydroxyphenyl) propane (concentration = 1 mol / l in dian), 2.8053, were dissolved in a flask at 100 ° С and vigorously stirring in 25 ml of DMSO (chemically pure). g (0.05 mol) of powdered non-carbonate KOH (chemically pure) and 3.1389 g (0.0125 mol) of 4,4'-dichlorobenzophenone. For azeotropic distillation of the water formed during the reaction, dried toluene (or chlorobenzene) was added to the flask taken from the calculation of its constant return from the Dean-Stark trap to the reaction flask, which leads to its economy. The temperature was gradually raised to 185 ° C. After azeotropic distillation of water and residues of toluene (chlorobenzene), the reaction mixture was kept at this temperature for 1 hour. Then, at the second stage, a mixture of 0.5183 g (0.00375 mol) of pre-calcined and ground K ₂ CO ₃ (hh), 2.7275 g (0.0125 mol) of 4,4'-difluorobenzophenone and 0, was added to the reaction flask. 03139 g (0.000125 mol) of 4,4'-dichlorobenzophenone in 25 ml of DMSO (chemically pure), while the concentration of the reaction mixture at the second oligo-polymer stage in terms of dian was 0.5 mol / L. Thus, the total molar ratio of diane, KOH, K ₂ CO ₂ and a mixture of 4,4'-difluoro- and 4,4'-dichlorobenzophenone in the sum of two stages was 1: 2: 0.15: 1.005. During the synthesis, the temperature was maintained with an accuracy of ± 0.2 ° C. The formation of PAEC after azeotropic distillation of water is 6 hours.

At the end of the synthesis, the reaction mixture was cooled, diluted with chloroform, the polymer was precipitated in ethanol or isopropanol. The precipitate was washed with alcohol, water, again with alcohol and dried with a gradual increase in temperature to 100 ° C. Then the polymer was dried under vacuum.

Polymer yield = 98.2%, η _ol = 0.89 dl / g (chloroform).

Example 2. As in example 1, only in the second stage, instead of K ₂ CO ₃ (hh), 0.39746 g (0.00375 mol) of previously calcined and ground Na ₂ CO ₃ (hh) were taken.

The polymer yield is 98.0%, η _ol = 0.85 dl / g (chloroform).

Example 3. As in example 1, only in the first stage, the starting compounds were dissolved in 50 ml of DMSO (concentration = 0.5 mol / L diane), in the second stage, the mixture of substances was added in solid form without DMSO.

The polymer yield is 98.0%, η _ol = 0.77 dl / g (chloroform).

Example 4. As in example 1, only the reaction was carried out for 7 hours.

The polymer yield is 98.0%, η _ol = 0.91 dl / g (chloroform).

Example 5. As in example 1, only dihalogenobenzophenones were taken in strictly equimolar amounts.

The polymer yield is 97.8%, η _ol = 0.68 dl / g (chloroform).

Example 6. As in example 1, only the total molar ratio of diane, KOH, K ₂ CO ₃ and a mixture of 4,4'-difluoro- and 4,4'-dichlorobenzophenone in the sum of two stages was 1: 2: 0.3: 1.005 , i.e. the molar ratio of K ₂ CO ₃ to 1 mole of diane, instead of 0.15, was 0.3 mol.

The polymer yield is 98%, η _ol = 0.88 dl / g (chloroform).

The structure of the synthesized polymers was proved by elemental analysis and IR spectroscopy. The molecular weight of the polymers synthesized with _straight η = 0,68-0,91 dl / g, M _W ≈70000-90000.

The proposed new continuous two-stage method for the synthesis of aromatic polyetherketone based on potassium diphenolate diane and 4,4'-dichloro and 4,4'-difluorobenzophenone is based on kinetic and thermodynamic studies carried out in [Musaev Yu.I. Synthesis features and reaction mechanisms for the production of polyarylates, aromatic polyethers and polypyrroles in non-aqueous media. - Nalchik, 2004 - Thesis for the competition. Doctorate Chem. sciences].

Below are the justifications for the found conditions for the synthesis of PAEC from the standpoint of intensification, optimization and cheapening of the process:

1. Advantages of DMSO as a solvent:

but. Dimethyl sulfoxide is produced on an industrial scale (waste from the pulp and paper industry), it is cheaper and significantly less toxic than other ADPRs.

b. It is better than other ADPRs; at elevated temperatures it dissolves bisphenol phenolates, i.e. it becomes possible to carry out the reaction in a homogeneous environment.

at. During the synthesis of the polymer in DMSO, a whole gamma of complex superbases ^is simultaneously present in various combinations: ^- OH - hydroxyl, ^- O-Ar ~ - phenoxide and ^- CH ₂ -SO-CH ₃ - dimsyl anions. Such "universal" systems with different alkaline agents have the most pronounced positive synergistic effect on the course of the polymer production process compared to other ADPRs.

2. The effect of temperature on the process conditions

With increasing temperature, the solubility of alkali metal phenolates increases, while the reaction rate increases and the effects of homo- and heterocoordination decrease (see section 3 below), which reduce the reactivity of polymer-forming functional groups. Thus, upon receipt of the PAEK DMSO in each condensation step should be carried out at 185 ° C, as close to the boiling point of DMSO (t ° = 189 _boiled C). All this favors the formation of the polymer and reduces the synthesis time. It should be noted that the use of dimethylacetamide as an ADPR (t _bale = 165.5 ° С, DMAA - prototype) increases the fire hazard and does not make it possible to reach 185 ° С in the reaction mixture without violating the optimal synthesis conditions.

3. The influence of the chemical structure of the starting monomers

The kinetic data obtained by us for the reaction of PAEC synthesis in DMSO indicate that the reactivity of both functional groups in 4,4'-dichlorobenzophenone is significantly lower than that of 4,4'-difluorobenzophenone. Along with this drop in reactivity is observed both polimerobrazuyuschih functional groups -O ^- and / or -Cl (F) through the formation of bonds between geterokoordinatsionnyh phenoxide anions ^(- O-Ar ~) and> C = O groups in digalogenbenzofenonov ADPR. In addition, during the synthesis, “terminal” phenoxide anions are formed, which are significantly less active with respect to DCBP than the initial diphenoxide anions of diane.

Thus, at the first stage of the formation of the diphenoxide anion ^, OC ₆ H ₄ -C (CH ₃ ) ₂ -C ₆ H ₄ -OC ₆ H ₄ -CO-C ₆ H ₄ -OC ₆ H ₄ -C (CH ₃ ) ₂ —C ₆ H ₄ —O ^— 4.4′-dichlorobenzophenone should be charged first. To increase the reaction rate, it should be carried out at a solution concentration of C = 1 mol / L in terms of diane diphenolate, because at this stage, there is no diffusion inhibition of the reaction due to a significant increase in the viscosity of the solution, observed at high degrees of completion of the process (in the case of the prototype, the concentration of the solution during the entire process was maintained at C = 0.5 mol / L). Due to a 2-fold excess of highly active diphenoxide anions of diane, the first stage at a temperature of 185 ° C is completed quite quickly (within one hour). The addition of highly active 4,4'-difluorobenzophenone in anhydrous DMSO at the second oligo-polymer stage (starting with the "dimer") made it possible to complete the synthesis at a high speed at an optimal solution concentration of C = 0.5 mol / L in τ≈6–7 hours.

4. Justification of the loading order in the first stage

We obtained the best results with the so-called one-stage flow of the first stage of the process (all starting materials are loaded, then azeotropic distillation of water and the polycondensation process occur simultaneously). In our case, this method is applicable, because the rate of adverse reaction of the alkaline hydrolysis of 4,4'-dichlorobenzophenone, which impedes the process, is much lower than the rate of the condensation reaction (in contrast to 4,4'-difluorobenzophenone). In addition, with such a load, the probability of the formation of inactive coordination-related functional —O ^- groups decreases, since they primarily interact on 4,4'-dichloro bonds, especially since their concentration is 2 times higher than the less active> C = O groups.

5. Replacing half of 4,4'-difluorobenzophenone with cheaper 4,4'-dichlorobenzophenone will significantly reduce the cost of production.

6. Evidence of the formation of diphenoxide anion in the first stage

^- OC ₆ H ₄ -C (CH ₃ ) ₂ -C ₆ H ₄ -OC ₆ H ₄ -C (O) -C ₆ H ₄ -OC ₆ H ₄ -C (CH ₃ ) ₂ -C ₆ H ₄ - O ^- .

To prove receipt of the dimer, at the end of the first stage, the reaction mass was poured into an excess of 0.1 N HCI solution, the precipitated dimer was filtered off, washed with distilled water, the filtrate and the washings were collected in a 1 L volumetric flask, and distilled water was added to the mark. 50 ml aliquots were titrated with 0.1 N carbon-free NaOH solution. Isolated from the reaction medium, washed, dried and reprecipitated "dimer" had t _PL = 98 ° C. Elemental analysis confirmed the formation of a compound of composition C ₄₃ H ₃₈ O ₅ (found%: C = 81.45; H = 6.05; Cl was absent. Calculated%: C = 81.39; H = 5.99). In the IR spectrum of the "dimer" there were absorption bands in the region of 690 (aromatic ring), 1665 cm ^-1 (> C = O), 1244 cm ^-1 (Ar-O-Ar), 1365 cm ^-1 (-CH ₃ ) , 3300 cm ^-1 (-OH). The method of differentiated non-aqueous potentiometric titration in a mixture of tert-butyl alcohol: dimethyl sulfoxide (titrant - tetrabutylammonium hydroxide) showed two kinks at the neutralization points of the first and second hydroxyl groups of the obtained compound. The amount of titrant used for titration corresponded to the calculated amount of hydroxyl groups in the sample taken.

Claims (1)

The method of producing polyetherketone, which consists in the interaction of diphenoxide anions of 2,2-bis (4-hydroxyphenyl) propane (diane) with 4,4'-dihalogenobenzophenone in an aprotic dipolar solvent at a temperature of 185 ° C, characterized in that the synthesis of polyetherketone proceeds in dimethyl sulfoxide in two stages, in the first stage by the reaction of diane with 4,4'-dichlorobenzophenone (molar ratio 1: 0.5) at a solution concentration of C = 1 mol / L in diane for 1 h after azeotropic distillation of water at a temperature of 185 ° C in the presence of solid powdered KOH receiving a potassium diphenolate dimer with the following structure of the diphenoxide anion -OC ₆ H ₄ -C (CH ₃ ) ₂ -C ₆ H ₄ -OC ₆ H ₄ -CO-C ₆ H ₄ -OC ₆ H ₄ -C (CH ₃ ) ₂ -C ₆ H ₄ -O-, at the second final oligo-polymer step, a mixture of 4,4'-difluorobenzophenone and 4,4'-dichlorobenzophenone with pre-calcined and ground K ₂ CO ₃ (molar ratio dian: 4, 4'-difluorobenzophenone: 4,4'-dichlorobenzophenone: K ₂ CO ₃ = 1: 0.5: 0.005: 0.15) in anhydrous dimethyl sulfoxide, the optimal concentration of the reaction mixture at this stage in terms of dian being 0.5 mol / l, total time I am carrying out the reaction for 6-7 hours.