IL26569A - Production of aromatic polymers and intermediates therefor - Google Patents

Description

ΈΔΧΕΉΧΆ -FORM - J5JQ..3.

PATENTS AND DESIGNS ORDINANCE PRODUCTION^OF_ ARO^TIC_ POLYMERS A D_ i T^SMEDIAXES.THEREFOR \ We, IMPERIAL CHEMICAL INDUSTRIES LIMITED, a British Company, of Imperial Chemical House, Millbank, London, S. W. 1. England DO HEREBY DECLARE the nature of this invention and in what manner the same is to be performed, to be particularly described and ascertained in and by the following statement :- Po 18742/1 004/19OO5/I9OO6/I 1 his invention relates to the production of aromatic polymers and intermediates therefor.

According to the invention, aromatic polymers whose molecular chains comprise benzenoid groups and oxygen or sulphur atoms and substances polymerisable to give such polymers are produced by a method in which a dihalogenobenzenoid compound having each halogen atom activated by an inert electron-attracting group is caused to react with a substantially equivalent amount of an alkali metal hydroxide, hydrosulphide or sulphide by the displacement of alkali metal halide in a polar liquid which is an ionising solvent for alkali metal phenoxides or thiophenoxides and is stable under the reaction conditions employed^ The halogen atoms in the dihalogenobenzenoid compound are preferably chlorine or fluorine. The fluorine derivatives generally are more reactive and enable the displacement of alkali metal halide to be carried out more quickly- bxit are more expensive^ Bromine derivatives are also relatively expensive and although they resemble the chlorine derivatives in performance they would seem to offer no advantages.. Iodine derivatives are generally less suitable.

Any dihalogenobenzenoid compound or mixture of dihalogenobenzenoid compounds is suitable for the invention provided the two halogen atoms are linked to benzene rings which have an electron-attracting group, preferably ortho or para to the halogen atom. The dihalogenobenzenoid compound can have the halogen atoms linked to the same benzenoid ring or to different benzenoid rings, so long as each is activated by an electron-attracting group.

Any electron-attracting group inert under the conditions of the reaction can be used as the activating group in these compounds. The more powerful electron-attracting groups give the highest reaction rates and are therefore preferred. Electron-donating groups should be absent P. I8742/1 OO /19OO5/1 OO6/1 114 group that activates one or more halogen atoms in the same ring, for example a nitro4, phenylsulphonyl, alkylsulphonyl , cyano , trifluoromethyl or rdtroso group, or heteronitrogen as in pyridine | or it may be a bivalent group that can activate halogen atoms in two different rings, for example a sulphone, sulphoxide, azo , carbonyl, vinylene, vinylidene, tetrafluoroethylene or organic phosphine oxide group; or it may be a bivalent group that can activate halogen atoms on the same ring, as in the case of difluorobenzoquinone and 1 ,4-, 1 ,5- or ,8-difluoroanthra-qu none.

In particular, the dihalogenobenzenoid compound may have the formula X X» in which X and X· are conveniently the same but may be different and are halogen atoms., and Y is -SO^-, -SO- or -CO- or a radical of the formula -Y' -A-Y"- in which Ys and Y" may be the same or different and each is -SO^-j -SO- or -CO- and A is a bivalent organic radical, which may be aliphatic, aromatic or heterocyclic and has both valencies linked to carbon atoms. For example A may be a bivalent aromatic radical derived from benzene, a f used-ring aromatic hydrocarbon containing not more than two aromatic rings (for example naphthalene, indene, fluorene or dibenzo-furan) , or a compound of the formula P.18742/ 9004/19OO5/I9OO6/I9 4 in which Z is a direct link, -0-, -S-, -SO,,-, -C0-T, a bivalent hydrocarbon or substituted hydrocarbon radical (e.g. alkylenes alkylidene or a bivalent cycloalipha ic or aromatic radical) s or a residue of an organic diol (i.e* the bivalent radical obtained by removing the hydrogen atoms from the two hydroxy groups) . The halogen atoms in the dihalogeno-benzenoid compounds are peierably in the para position to the bridging group Y„ because the essentially all-para polymers that can be made from them have better physical properties as thermoplastic materials.

Lower alkyl, alkoxy or alkylthio groups may be present as substituents on any of the aromatic rings but are preferably absent from the halogen-bearing rings and are also preferably absent altogether when the aromatic polymer is required to be stable at high temperatures.

If desired the polymers can be prepared from mixtures of two or more dihalogenobenzenoid compounds, and these may contain different electron-attracting groups.

The alkali metal cation associated with the hydroxide, hydrosulphide or sulphide anion is conveniently potassium or sodium. Displacement of alkali metal halide often occurs more readily if the potassium cation is present in the reagent used, but the weight (and usually the price) per mole of a potassium compound is higher than for the corresponding sodium compound. Some or all of the alkali metal cation in the reagent may be replaced by an organic onium cation having a positively charged hetero-atom (for example a quaternary ammonium cation such as tetramethyl-amraonium) stable under the conditions of the reaction, and the term "alkali metal salt" as used herein is deemed to refer also to salts containing such onium cations.

In the reaction of the invention, one mole of the dihalogenobenzenoid compound is used for t¾?o moles of the alkali metal hydroxide or hydrosulphide or one mole of the alkali metal sulphide; i.e. the P.18742/ OO4/I9OO5/ 9006/ 9 14 the reagents suffer some decomposition or otherwise be lost from the reaction mixture it may be added initially in slight excess.

In the formation of a polymer, some oxygen atoms as well as sulphur atoms may be introduced into its molecular chain when an alkali metal hydrosulphide or sulphide is used, because these anions are hydrolysed to some extent by water to yield hydroxide anion which may itself take part in the reaction* Suitable polar liquids for the reaction include: the lower dialkyl and cyclic alkylene sulphoxides and sulphones (e.g. dimethyl sulphoxide and 1,1-dioxothiolan) , nitriles (e.g. benzonitrile) , diaryl ketones (e..-g« benzophenone) , diaryl sulphoxides and sulphones, ethers (eggc dioxane, diethylene glycol dimethyl ether, diphenyl ether, methoxy-phenyl ethers), non-olefinic tertiary alcohols (e.g. t-butanol) , and water. Mixtures of such substances may conveniently be used, e.g. when one or more components of the mixture would otherwise be solid at the reaction temperature. The liquid (or mixture of liquids) should preferably be a solvent also for the dihalogenobenzenoid compound and preferably also for the alkali metal hydroxide, hydrosulphide or sulphide. The amount of the liquid is relatively unimportant provided it is sufficient to dissolve alkali metal salts of phenols or thio-phenols produced in the reaction and is not too large to be economically disadvantageous. The total amount of solvent used is desirably sufficient to ensure that none of the starting materials are in the solid state in the reaction mixture* The liquid initially present in the reaction medium need not be the same as that present during the final formation of the polymer. The original liquid may be allowed to remain during the reaction.-, with the subsequent addition of any desired solvents, or it may be removedv e.g. by distillation.

Changing the liquid reaction medium may be convenient as it allows P.18742/19OO4/19OO5/ 9OO6/1 1 4 stages, being for example inconveniently volatile or unstable at polymerisation temperatures or incapable of dissolving the resultant polymer to the desired extent* For example, dimethyl sulphoxide is a convenient solvent but cannot be used at such high temperatures as 1 ,1-dioxothiolan (cyclic tetramethylene sulphone) which may therefore be substituted for it during the reaction.

The liquid reaction medium need not contain any solvent for polymer of high molecular weight even at the later stages of the reaction, although if it does not the product is of relatively low molecular weight unless the final stage of polymerisation is carried out in the melt; this may be explained if the molecular chains of the polymer cease to grow in the solid state* For the production of low polyme s the polar liquid may conveniently be water or a mixture of water and another liquid or liquids stable to heat under alkaline conditions. The dihalogenobenzenoid compounds are generally immiscible with water and the reaction mixture therefore usually consists of two phases. Vigorous stirring and the use of a suitable emulsifier are then helpful in maximising the interfacial area and hence reaction rate.

The rate of polymer formation in the reaction of the invention rises with rise of temperature and below 200°G is uneconomically slow.

It may however be advantageous to preheat the reaction mixture between 150°C and 200°C until inorganic hydroxide, hydrosulphide and sulphide anions are no longer present and then raise the temperature to produce the polymer. Temperatures up to 400°C may be employed, and 250-350°C is usually convenient.

The reaction should initially be carried out under pressure if necessary to prevent the escape of dihalogenobenzenoid compound and any volatile solvent or cosolvent. Heating in vacuum may however be P.18742/19OO4 I9OO5/I 006/19114 sulphoxide which decomposes at the temperatures required to produce high polymer.

The vessel used should be made of or lined with a material that is inert to alkali metal hydroxides, hydrosulphides or sulphides and also to alkali metal halides under the conditions employed* For example, glass is unsuitable as it tends to react with hydroxide anion at high temperatures, upsetting the stoichiometry of the polymerisation and contaminating the product with silicate. Some grades of stainless steel undergo surface crazing at these temperatures in the presence of alkali metal halide.j and vessels made of or lined with titanium or nickel or an alloy thereof or some similarly inert material would be preferable.

The polymerisation must be concluded under substantially anhydrous conditions to obtain products of high molecular weight. Water is formed in the reaction when an alkali metal hydroxide is used, and when an alkali metal sulphide or hydrosulphide is used it is convenient to employ a hydrated salt and to dissolve it initially in a little water. The water must then be removed, conveniently by distillation, e.g. direct or by azeotropic distillation. Any inert volatile liquid that forms an azeo-tropic mixture with water may be used; benzene, xylene and halogenated benzenes are convenient examples. This liquid need not itself be thoroughly removed after all the water has gone. Sometimes it is convenient3 particularly when an alkali metal hydrosulphide or sulphide is being used, to add initially only half an equivalent of the dihalogeno-benzenoid compound and then to remove as much v/ater as possible from the polymerisation mixture before adding the rest of the dihalogeno-benzenoid compound* It is often advantageous to keep the temperature below 150°C (preferably at about 100°-140°C) until all v/ater has been removed, and then to conclude the reaction at a temperature between 150°C and 350°CC Ρ.18742/1 004/19005/19006/ 14 The reduced viscosity of the polymer is desirably at least 0»3 (measured at 25°C at Λ% in a solvent such as dimethyl formamide) if it is to serve for structural purposes,, To neutralise any reactive oxygen- or sulphur-containing anions, a reagent therefor may be introduced at the termination of the polymerisation. Reactive monofunctional halides, for example methyl chloride, are particularly suitable* It has been found that an alkali metal salt of a 4-(4-halogenophenylsulphonyl)phenol or 4- (4-halogenobenzoyl) henol and hence the phenol itself are surprisingly readily obtained by the action of an alkali metal hydroxide on a bis-(4-halogenophenyl) sulphone or ketone in a polar liquid v/hich is an ionising solvent for the phenoxide and is stable under the conditions employed. Very little salt of bis-(4-hydroxy-phenyl) sulphone or ketone is formed.- except in the presence of excess alkali at high temperatures, because the second halogen atom in the bis-( -halo enophenyl) sulphone or ketone is unexpectedly much less susceptible than the first to alkaline hydrolysis, and the desired salt of a 4-(4-halogenophenylsulphonyl)phenol or 4-(4-halogenobenzoyl)phenol can be isolated in excellent yieldo Such salts in the solid state are novel and have been found to be valuable intermediates for the production of aromatic polymers, the molecular chains of which comprise para-phenylene groups, oxygen atoms, and sulphone or ketone groups„ When such a salt is heated at or above its melting point in the substantial absence of any diluent reactive under the conditions employed, polymer of high molecular weight can be obtained with the elimination of alkali metal halide. The starting material need not consist of a pure reagent but may comprise such materials mixed with each other and/or mixed with some preformed low polymer.

P.18742/1 OO4/I OO5/I90C6/ 14 The reaction to produce this polyraerisable salt may be carried out at temperatures up to 200°C but is preferably carried out below 50°C because above this temperature some polymer or some alkali metal salt of the bisphenol or both may be formed. Temperatures above room temperature and preferably above 60°C are desirable for the reaction to occur at an economic rate. With a liquid in which both starting materials are soluble, 100-140°C is generally convenient. However,, with water alone (which is not a solvent for the dihalogenobenzenoid compound) t temperatures above 150eC are convenient so that the dihalogenobenzenoid compound is molten> The alkali metal salt of the phenol is initially obtained dissolved in the reaction medium and is preferably isolated directly, although for the purpose of purification it may be more convenient in some cases to acidify and then isolate the free phenol. This can be converted back into an alkali metal salt by treatment with a suitable base (e.g* an alkali metal hydroxide or alkoxide).

A 4-(4-halogenophenylsulphonyl)phenol or 4-(4-halogenobenzoyl)-phenol is a useful product in its own right, possessing a halogen atom as well as the phenolic group; and can serve as a valuable chemical inter-mediate.. For example the halogen atom can be replaced by amino or substituted amino groups giving a wide variety of materials.

The polymeric products of low molecular weight which may be produced by the method of the invention e.g.. those formed in the presence of water or at temperatures below 2CQ°C also may find industrial uses directly, for example as sizes and finishes or as lubricant additives or thickeners for non-aqueous liquids. Products with a preponderance of halogen end-groups or of anionic oxygen- or sulphur-containing end-groups may be prepared by employing a slight excess of the dihalogenobenzenoid compound or of the alkali metal hydroxide, hydrosulphide or sulphide respectively.

P„187 2/ 9OO4/I9OO5/I OO6/I911 thiophenolic groups by acidification.

The low polymers are also useful as intermediates for the production of various high polymers,, A low polymer with predominantly anionic end-groups, for example, can react with a benzenoid compound containing at least three activated halogen atoms to give a thermoset material. Free phenolic end-groups may be linked further in conventional manner, e.g. with diisocyanates.

If the stoichiometry of the initial reaction is carefully preserved, so that activated halogen end-groups and anionic oxygen- or sulphur-containing end-groups are present in approximately equal numbers in the low polymers, these can be converted (like the alkali metal salts of the halogenophenols described above) directly into thermoplastic high polymers by heating at 200-400°C (preferably 250-350eC) in the substantial absence of water or any other liquid diluent reactive under the conditions employed. This reaction is conveniently carried out in an extruder.

The alkali metal halide resulting from the initial reaction with the dihalogenobenzenoid compound need not be removed before the subsequent anhydrous heating; together with further alkali metal halide formed in the latter step it can all be removed from the resultant high polymer by any suitable means. For example, it can be extracted from the high polymer using water, or the polymer itself can be dissolved in a strongly polar organic solvent (for example dimethyl formamide, 1-methyl-2-oxo-pyrrolidine, dimethyl sulphoxide, , -dioxothiolan or nitrobenzene) and then reprecipitated by addition to a liquid such as water which is miscible with the polymer solvent but itself a non-solvent for the polymer.

When the polymer is formed in solution, a convenient procedure is to add the reaction mixture (which may be decanted or filtered from solid alkali metal halide) to an excess of a liquid which is miscible P.18742/I9OO /I9OO5/I OO6/ 911 the reaction solvent is water-miscible,; or is raiscible with a liquid in which residual alkali metal halide also dissolves, the polymer can thus be obtained in one step<> Otherwise, as for example if the reaction mixture is poured into methanolβ the precipitated polymer initially contains alkali metal halide which can subsequently be washed out with water0 The following examples illustrate the invention, EXAMPLE 1 Bis-(4-chlorophenyl) sulphone (14.35 g? 0^0 mole), aqueous 141% w/w sodium sulphide solution (27 Polymers may similarly be obtained as in these examples from bis-(4-fluorophenyl) sulphone, bis-(4-chlorophenyl) sulphoxide, 4s4'-dichloro-berizophenone, 4,4'-bis-(4-chlorophenylsulphonyl)diphenyl, and 4-(4-chlorophenylsulphonyl)phenoxy- 9-chlorobenzophenone«, EXAMPLE 3 Bis-(4-chlorophenyl) sulphone (14* 35 g; 0*0 mole), aqueous potassium hydroxide solution (12.88 g; 0,10 mole of KOH) and dimethyl sulphoxide ( 100 cm^) were stirred together in a stainless steel reaction vessel under a blanket of nitrogen for 24 hours at 100°C. Benzene (140 cm^) was added and water (7 cm^) was removed as benzene-water azeo-trope and then most of the benzene was removed by distillation. , 1-Dioxothiolan (100 cm^) was added and dimethyl sulphoxide was distilled off at 5 °C under reduced pressure (1.5 torr). When the dimethyl sulphoxide had been removed, the mixture was stirred under nitrogen at 220°C for 24 hours, cooled, and poured into ethanol. The precipitated product was washed with ethanol and water and dried to yield a polymer (11.4 g) of reduced viscosity OdO at 1 in dimethyl formamide at 25° 0.

EXAMPLE 4 Bis-(4-chlorophenyl) sulphone (287 g$ 1 mole), potassium hydroxide (112 g; 2 moles) and water (1 »7 drn^) were shaken in a stainless steel autoclave for 18 hours at 195-200°C. The product was cooled and added P, 1874-2 9004/19005/ 006/191 4 was added until the ρΗ was -below 2-0 and more solid was precipitated. The whole was extracted with diethyl ether (2 dm^) after which a solid remained suspended in the aqueous phase? This solid was filtered off,, washed with water and dried to give a polymer (12 g) shown by infra-red spectroscopy to contain units of the formula Monomeric material was isolated from the ethereal phase as follows,, Potassium hydroxide solution O.ON, 2 dm^) was added to extract phenolic material from residual bis-(4-chlorophenyl) sulphone (of which 0, 15 mole was recovered). The aqueous alkaline solution was then acidified with concentrated hydrochloric acid to precipitate a mixture of phenolic material (17 g) which separated as a gum. This was digested with hot chloroform (0: 5 dm^) leaving a residue of bis-(4-hydroxyphenyl) sulphone (71 g; 0 ,28 mole) identified by infra-red spectroscopy. The solution v/as evaporated to yield 4-(4-chlorophenylsulphonyl)phenol (99 g» 0„37 mole) identified by infra-red spectroscopy,-.

EXAMPLE^ The rate of hydrolysis of bis-(4-chlorophenyl) sulphone (14.36 g; O. O5 mole) in the presence of 5 w/w aqueous potassium hydroxide (26 g, 0, 20 mole KOH) in solution in dimethyl sulphoxide (100 cm^ was ·. studied at 100°C, 120°C and 140°C. The extent of hydrolysis was measured by gravimetric estimation of chloride ion at various reaction times. In Figure 1 of the accompanying drawings, the results are presented as a graph in which the abscissa is the reaction time in hours and the ordinate is the amount of chloride ion as a percentage of the total amount of chlorine substituent in the bis-(4-chlorophenyl) sulphone.

At 140°C, complete hydrolysis was occurring. At 12G°C the two P.18742/19004/19OO5/I9OO6/I 1 and at 100°G hydrolysis beyond the half-way stage was very slow. The second chlorine substituent was hydrolysed only at about one-hundredt the rate of the first. In this experiment there were two liquid phases present initially but only one phase during the latter part of the hydrolysis.

EXAMPLE 6 The experiment described in Example 5 was repeated using only two molar equivalents of potassium hydroxides Two liquid .phases ¾rere present throughout. In Figure 2 of the drawings, where the abscissa and ordinate are as in Figure 1„ the results show that the removal of the chlorine substituent from potassium 4-(4-chlorophenylsulphonyl)phenoxidei either by formation of polymer or by hydrolysis to give the bisphenol and potassium chloride, is very slow at 100°C and at 140°C over 24 hours, since the curves for both these temperatures virtually level off with time at the stage of 5 ¾ formation of chloride ion.

EXAMPLE 7 The experiments described in Examples 5 and 6 were repeated using 1 ,1-dioxothiolan instead of dimethyl sulphoxide as solvent. The hydrolysis appeared to proceed more slowly, in spite of vigorous stirring. Two liquid phases were present throughout both experiments.

EXAMPLE 8 Pure bis-(4-chlorophenyl) sulphone (359 g» 1.25 mole), potassium hydroxide solution (64 g; containing 5«0 moles of KOH) and dimethyl sulphoxide (2.5 dm^) were stirred under nitrogen in a stainless steel vessel for 5 hours at 100°C and then poured into water (10 drn^). The milky solution was acidified with nitric acid and 4-(4-chlorophenyl-sulphonyl)phenol precipitated; analysis of the solution for chloride ion shov/ed 1°3> hydrolysis of the chlorine substituents in the starting material. The 4-(4-chlorophenylsulphonyl)phenol was extracted into ether.

P 18742/19004/ 9OO5/ 006/19 14 separate phenolic material from any unhydrolysed starting material) ~ and the sodium hydroxide solution was acidified once again to give 4=(4- chlorophenylsulphonyl)phenol (320 g: 95„ % yield), m.p. 143-145°C, probahly contaminated with a little bis-(4-hydroxyphenyl) sulphone. The product was dissolved in hot toluene, in which the bis-phenol is sparingly soluble (about 0. ), filtered hot and allowed to crystallise. Recrystallisation was carried out from chloroform containing active charcoal and yielded a product of m.p. 145-146eC It was soluble in cold aqueous potassium hydroxides sodium carbonate or potassium carbonate but insoluble in warm aqueous sodium bicarbonate and (like phenol itself) was precipitated from its solution in potassium hydroxide by carbon dioxide.

The potassium salt was isolated as a yellowish powder, n p* 274-276°C, by the reaction of an ethanolic solution of 4-(4-chlorophenylsulphonyl)phenol with an equimolar amount of potassium ethoxide (under anhydrous conditions) or of aqueous potassium hydroxide. The salt was soluble in cold dimethyl formamide, cold dimethyl sulphoxide, warm ,1-dioxothiolant warm ethanol and hot nitrobenzene. Exposure of the salt to the atmosphere (relative humidity about 5$) resulted in a weight increase of in 90 minutes, corresponding to the formation of a monohydrate, and the colour changed from yellow to pure white*.

To prepare a polymer,, the potassium salt of 4-(4-chlorophenylsulphonyl)phenol (3.Ο7 g; 0.01 mole) was heated in an evacuated glass tube for 1 hour at 30°Ce The tube was cooled and broken open. The product was crushed and warmed with dimethyl formamide (30 cm^) , in which potassium chloride is largely insoluble, to dissolve the polymer. The solution was filtered and poured into water ( crn^) with vigorous agitation. The precipitate was washed with water and dried to give a colourless polymer (2.2 g) having a reduced viscosity of 0„60 in a 1% solution in dimethyl formamide at 25°C, Ρ,, 18742/19004/1 005/1 006/ 14 EXAMPLE 9 Aqueous potassium hydroxide (26.00 containing 0.20 mole KOH) was added to a solution of bis-(4-chlorophenyl) sulphone (28.7 gi ■z 0,1 mole) in dimethyl stilphoxide (200 cm ) in a stainless steel vessel. The mixture was stirred under nitrogen for 24 hours at 1G0°C. Water and dimethyl sulphoxide were removed by distillation at about 1 torr while the temperature was raised to about 180°C„ The last traces of dimethyl sulphoxide were removed by crushing the product and heating it at about 180°C for 2 hours at about 10"-5 torr.

The dried solid was heated at 300°C for ° minutes in a stainless steel vessel under nitrogen. After cooling, the product was crushed and warmed with dimethyl formamide (300 cnr"5) to dissolve the polymer while potassium chloride and a sraall amount of resin remained undissolved and were filtered off. The solution was poured into water (1500 cur with vigorous agitation. The precipitate was washed with water and dried to give a colourless polymer (16 ,5 g) having a reduced viscosity of 0.49 in. a 1 solution in dimethyl formamide at 25°C.

The polymer was compression-moulded at 320°C for 5 minutes to give a tough transparent film*.

EXAMPLE 10 Bis-(4-chlorophenyl) sulphone was hydrolysed as described in Example 9 b aqueous potassium hydroxide in dimethyl sulphoxide over 24 hours at 100°C. The solution so obtained was cooled to room temperature and decanted through a filter to remove potassium chloride: on the assumption that the potassium salt of 4-(4∞chlorophenylsulphonyl)-phenol had been produced, this removed 97$ of the potassium chloride formed, the rest stayed in solution. The resulting mobile yellow solution was placed in a rotary evaporator and the pressure was reduced to below 1 torr as the temperature was progressively raised over P,18742 1900/19OO5/19OO6/I 114 remaining was a yellow solid containing about 40%' of the potassium salt of 4-(4-chlorophenylsulphonyl)phenol, about 60% of a low polymer of reduced viscosity 0,06 (in a Λ% solution in dimethyl formamide at 25°C) * about 0Λ% of dimethyl sulphoxide, and other substances in low concentration.

This product (11,.5 g) was polymerised at 280°C for 30 minutes in a glass tube which was continuously evacuated by a high-vacuum pump. The volatile substances evolved were collected (0o06 g) and consisted of about 40% water and 60$ dimethyl sulphoxide* The solid product from the polymerisation was crushed and warmed with dimethyl formamide (100 cm3) and filtered to remove insoluble material; this was entirely potassium chloride and no insoluble polymer was presents The solution of polymer in dimethyl formamide was poured itfith stirring into water (1 dm ) to precipitate the polymery which was washed with water and then with methanol and dried in vacuum at 15 °0,> The product (8*6 ; 99$ yield) had a reduced viscosity of 0,^52 in a Λ% solution in dimethyl formamide at 5°C¾ and gave a strong tough compression moulding, A similar polymerisation carried out without continuous evacuation (i.e.. without continuous removal of dimethyl sulphoxide or some harmful decomposition product) yielded a polymer of bad odour and colour and of lower molecular weight but containing up to 20 of polymeric material (probably cross-linked) insoluble in dimethyl formamide* EXAMPLE 11 Bis-(4-chlorophenyl) sulphone was hydrolysed as described in Example 3 b aqueous potassium hydroxide in dimethyl sulphoxide over 24 hours at 1QG°C~ The solution in dimethyl sulphoxide was cooled and decanted from solid potassium chloride and 1 ?1-dioxothiolan ( 5 cm3) was added- Dimethyl sulphoxide was removed by distillation at 10 torr and some 51-dioxothiolan was also allowed to distil to sweep away the P.137 -2/1 OO -/19OO5/1 0O6/1911 the product was an 80$ w/w solution of the crude potassium salt of 4-(4-chlorophenylsulphonyl)phenol in 1 , 1-dioxothiolan, When cold, the solution solidified as a brittle material completely soluble in water.

When this material was heated in nitrogen for 7 hoirs at 240°C, a polymer was formed having a reduced viscosity of 0o22 (in a 1$ solution in dimethyl formamide at 25°C)» If the material was first diluted with 1 , 1-dioxothiolan to give a concentration of 5$» heating under similar conditions yielded a polymer of reduced viscosity 0„ 18. In neither case was any polymer formed insoluble in dimethyl formamideo EXAI-IPLE 1 A solution of the potassium salt of 4-(4-chlorophenylsulphonyl) henol in dimethyl sulphoxide was prepared and decanted from potassium chloride as described in Example 10,, Most of the water and dimethyl sulphoxide were then removed by distillation at 25 torr, and when cold the product was powdered and placed in a rotary evaporator and the temperature was raised to 2.60°C while the pressure was 0, 1 torr. The product was a hard brittle prepolymer containing about 99$ low polymer (reduced viscosity 0,2 at 1$ in dimethyl formamide at 25°C) and about 1$ of the potassium salt of 4-(4-ehlorophenylsulphonyl)phenol; the concentration of dimethyl sulphoxide was less than 0, $ and probably less than 0„01 „ This prepolymer (5«0 g) was heated in vacuo for 30 minutes at 280°C in a glass tube. It was then cooled and dissolved in dimethyl formamide and separated from potassium chloride which was filtered off. The polymer was precipitated by adding the solution to waters the product (3·5 g) had a reduced viscosity of 0„58 (in a 1$ solution in dimethyl formamide at 25°C) and no polymer was formed insoluble in dimethyl formamide.

The prepolymer ( * 0 g) ¾ when heated in nitrogen for 30 minutes at 2S0°C in a glass tube and worked up as before, yielded a polymer (3»6 g) of reduced viscosity 0.-.62. No insoluble polymer i^ s formed.

P. 8742/1 004/1 005/ 9006/1911 The prepolymer (5.0 g) and 1 , -dioxothiolan (6-1 g) were stirred together and the temperature was raised to 220°C, when all the prepolymer appeared to have dissolved and the concentration of the solution was about 45$ w/w: Further polymerisation was carried out at 240°C for 4 hours; the solution was cooled and water was added to precipitate a polymer (3 ·7 g after washing and drying) having a reduced viscosity of 0,4-2.

EXAMPLE 13 Pure bis-(4-chlorophenyl) sulphone (14, 36 g; 0,05 mole) f aqueous sodium hydroxide (8 99 g» 0*10 mole NaOH) - and dimethyl sulphoxide ( 100 crn^) were stirred under nitrogen for 24 hours at 100°C in a stainless steel vessel, A tandem experiment shoied that 48 ,2$ of the chlorine initially present in the bis-(4-chlorophenyl) sulphone was present as chloride anion under these reaction conditions, Most of the dimethyl sulphoxide and water were removed by distillation at 20 torr; and the product was finally dried in a rotary evaporator at a temperature rising to 270°C at a pressure of 0.1 torr. The product was a yellow powder comprising about 20 of very low polymer and about 80 of the sodium salt of 4-(4-chlorophenylsulphonyl)phenol.

This product (lOf.02 g) was heated for 30 minutes at 300°C invacuq and worked up as described in Example 10 to give polymer (6. ,62 g; 8 yield) of reduced viscosity 0.26 (at 1$ in dimethyl formamide at 25°C).

A similar polymerisation carried out at 35°0 gave a polymer (3«8l g; 42$ yield) having a reduced viscosity of 0< ; together with a resin (4 . Ο g) insoluble in dimethyl formamide,, ECMPLE_14 Pure 4-(4-chlorophenylsulphonyl)phenol (21 87 g; 0.- 10 mole) -prepared as described in Example 8 ; was dissolved in ethanol (50 cw ) and aqueous sodium hydroxide (54.48 g; 0; 10 mole NaOH) was added-- The P.18742/19ΟΟ4/19ΟΟ5/19ΟΟ6/191 4 pressure and finally dried at 200°C for 24 hours under high vacuura, The sodium salt of 4-(4-chlorophenylsulphonyl) henol was obtained as an off-white solid of m.p, 320-325°C, Titration with 0.1N hydrochloric acid gave the purity as 99$· This pure sodium salt (Ο.96 g) was heated in vacuo above 3 °C for 0 minutes. The product was cooled, dissolved in dimethyl formamide and filtered to remove undissolved sodium chloride, and the polymer was precipitated by adding the solution to methanol. The precipitate was washed repeatedly with methanol and water and dried at 120°C in vacuo to give a polymer (0-75 g? 98 yield) having a reduced viscosity of 0,47 in a % solution of dimethyl formamide at 25°C.

Claims (14)

1. Having now particularly described and ascertained the nature of our said invention and in what manner the same is to be performed, we declare that what we claim is : 1 A method for the production of aromatic polymers whose molecular chains comprise benzenoid groups and oxygen or sulphur atoms and substances polymerisable to give such polymers, in which a dihalogeno-benzenoid compound having each halogen atom activated by an inert electron-attracting group is caused to react with a substantially equivalent amount of an alkali metal hydroxide, hydrosulphide or sulphide by the displacement of alkali metal halide in a polar liquid which is an ionising solvent for alkali metal phenoxides or thiophenoxides and is stable under the reaction conditions employed*

2., A method according to Claim 1, in which the polar liquid is also a solvent for the polymer produced.

3. A method according to Claim 1, in which the polar liquid is water or a mixture of water and another liquid or liquids stable to heat under alkaline conditions.

4. A method according to any of Claims 1 to 3 or the production of aromatic polymers, the molecular chains of which comprise para-phenylene groups oxygen atoms, and sulphone or ketone groups, and substances polymerisable to give such polymers, in which a bis-(4-halo ehophenyl) sulphone or ketone is caused to react with an alkali metal hydroxide by the displacement of alkali metal halide- 5- A method according to Claim 4¾- in which the reaction is carried out at a temperature below 200°C to produce a polymerisable substance

5. containing an alkali metal salt of a 4-(4-halogenophenylsulphonyl)phenol or 4-(4-halogenobenzoyl)phenolc

6. A method according to Claim 4 or Claim 5» which bis-(4-chloro-phenyl) sulphone is caused to react with potassium or sodium hydroxide. 7» A method for the production of aromatic polymers, the molecular chains of which comprise para-phenylene groups, oxygen atoms, and sulphone or ketone groups, in which an alkali metal salt of a 4-(4-halogenophenyl- -

7. displacement of alkali metal halide at a temperature above 200S>C in the substantial absence of any diluent reactive under the conditions employed.

8. , A method according to any of Claims 4 to 7 n which a aromatic polymer is produced by a reaction which is initially carried out at a temperature below 200°C in a polar liquid which is an ionising solvent for alkali metal phenoxides and is stable at the temperature employed,, this diluent being removed before the polymerisation is concluded at a temperature above 200°C in the substantial absence of liquid diluent. 9<- A method according to any of Claims 4 to 7 which an aromatic polymer is produced by a reaction itfhich is initially carried out at a temperature

9. 200°C in a polar liquid which is an ionising solvent for alkali metal phenoxides and is stable at the temperature employed., this diluent being replaced if necessary before the polymerisation is concluded at a temperature above 200CC in the presence of a diluent substantially unreactive under the conditions employed.

10. A polymerisable solid containing an alkali metal salt of a -(4-halogenophenylsulphonyl)phenol or 4-(4-halogenobenzoyl)phenol.

11. A polymerisable solid according to Claim 10, containing the potassium salt of 4-(4-chlorophenylsulphonyl)phenol.

12. - A polymerisable solid according to Claim 10, containing the sodium salt of 4-(4-chlorophenylsulphonyl)phenol0

13. 3. A method according to any of Claims 1 to 8 substantially as herein described with reference to the examples,,

14. An aromatic polymer or a .substance polymerisable to give such a polymer, when produced by a method as claimed in any of Claims 1 to 9 or by an obvious chemical equivalent thereof. DATED the 22nd September, 1966