Bisphenol salts

Polymerization via Nucleophilic Substitution Reaction. Halo- and nitro- groups attached to phthahmide groups are strongly activated toward nucleophilic substitution reactions. Thus polyetherimides ate synthesized by the nucleophilic substitution reaction of bishaloimides (59,60) and bisnitroimides (61,62) with anhydrous bisphenol salts in dipolar aptotic solvents. 

A preferred synthetic procedure to PAEH concerns the formation of the bisphenolate salt followed by the addition of the activated difluoro, dichloro or dinitro monomer. As an example, the heterocyclic bisphenol is stirred in a mixture of toluene and an aprotic polar solvent such as DMAc, NMP or diphenyl sulfone at 135-140 °C for several hours in the presence of 10 mol % excess of powdered anhydrous potassium carbonate (stoichiometric amount of sodium or potassium hydroxide can be used) under a Dean-Stark trap in a nitrogen atmosphere. Water is removed by azeotropic distillation. A stoichiometric quantity of the difluoro monomer is then added to the slightly cooled reaction mixture. The toluene is removed and the reaction is stirred at 155°C in DMAc for one to several hours. Polymer isolation is performed as previously described. This procedure minimizes hydrolysis of the difluoro monomer, gel formation and molecular weight equilibration of the polymer. 

The kinetics of aromatic polyether formation by the reaction of bisphenol salts with 4,4 -dichlorodiphenyl sulphone was studied by Schulze and Baron [205]. The potassium salts of three bisphenols were used, with dimethyl sulphoxide solvent. The rate was considerably faster in the early stages of the reaction, when the diphenoxide was present in higher concentrations than phenoxide chain ends. The faster reaction was assumed to be... 

Poly (etheretherketone) or PEEK, the structure of which is shown in Fig. 16.2, was originally developed primarily for composite applications. It is produced by the step-growth polymerization process of dialkylation of bisphenolate salts. PEEK is a semicrystalline thermoplastic with excellent mechanical and chemical resistance properties that are retained at high temperatures. It has a glass transition temperature or Tg at about 143 °C and melts around 343 °C. It is highly resistant to thermal... 

From Equation 1 it is apparent that the bisphenate formed must remain soluble in the system in order to achieve high molecular weight. Dimethyl sulfoxide has been used as the solvent of choice for the polymerization process. However, a large number of bisphenol salts have a limited solubility in such a solvent system. 

Development Center achieved this in the late 1970s [10], An important feature of this invention was the development of a process to make dianhydrides, specifically dianhydrides based on bisphenol-A. This was achieved by phase-transfer-catalyzed nucleophilic aromatic substitution, as shown in Eq. (8.4). Anitro group was displaced from a phthal-imide by a bisphenol salt to yield a difunctional imide compound, which, in turn, was converted to the bisphenol-A dianhydride (BPADA). Sodium nitrite is made as a by-product. 

As mentioned previously, the key to making BPADA was the development of nitro displacement chemistry, which forms ether hnkages as shown in Eq. (8.4). This chemistry allows bisphenol salts, commonly used to make polycarbonates and epoxies, to become monomers for polyimide synthesis. The bis AT-methyl imide intermediate is converted to the dianhydride that is used in imide polymerizations. Nitro displacement has been shown to work with many bisphenol salts to make a family of dianhydrides. The BPA dianhydride is commercially the most important. 

This can lead to solvation of the bisphenol salt in the dipolar aprotic-solvent or it can lead to hydrolysis of the bisphenol salt which produces sodium hydroxide. The latter can react with polymer end groups or with the activated dihalo compound such as dichlorodiphenyl sulfone. 

Polyethei sulfones (PES) piepaied fiom 4,4 -difluoiodiphenyl sulfone and bisphenol A (potassium salt, DMSO) react faster than the corresponding... 

The basic metal salts and soaps tend to be less cosdy than the alkyl tin stabilizers for example, in the United States, the market price in 1993 for calcium stearate was about 1.30— 1.60, zinc stearate was 1.70— 2.00, and barium stearate was 2.40— 2.80/kg. Not all of the coadditives are necessary in every PVC compound. Typically, commercial mixed metal stabilizers contain most of the necessary coadditives and usually an epoxy compound and a phosphite are the only additional products that may be added by the processor. The requited costabilizers, however, significantly add to the stabilization costs. Typical phosphites, used in most flexible PVC formulations, are sold for 4.00— 7.50/kg. Typical antioxidants are bisphenol A, selling at 2.00/kg Nnonylphenol at 1.25/kg and BHT at 3.50/kg, respectively. Pricing for ESO is about 2.00— 2.50/kg. Polyols, such as pentaerythritol, used with the barium—cadmium systems, sells at 2.00, whereas the derivative dipentaerythritol costs over three times as much. The P-diketones and specialized dihydropyridines, which are powerful costabilizers for calcium—zinc and barium—zinc systems, are very cosdy. These additives are 10.00 and 20.00/kg, respectively, contributing significantly to the overall stabilizer costs. Hydrotalcites are sold for about 5.00— 7.00/kg. 

The first aromatic sulfone polymer produced commercially was introduced as Bakelite polysulfone but now is sold by Union Carbide under the trade name Udel. It is made by reaction of the disodium salt of bisphenol A (BPA) with 4,4 -dichIorodiphenyl sulfone in a mixed solvent of chlorobenzene and dimethyl sulfoxide (eq. 12). 

Nucleophilic Substitution Route. Commercial synthesis of poly(arylethersulfone)s is accompHshed almost exclusively via the nucleophilic substitution polycondensation route. This synthesis route, discovered at Union Carbide in the early 1960s (3,4), involves reaction of the bisphenol of choice with 4,4 -dichlorodiphenylsulfone in a dipolar aprotic solvent in the presence of an alkaUbase. Examples of dipolar aprotic solvents include A/-methyl-2-pyrrohdinone (NMP), dimethyl acetamide (DMAc), sulfolane, and dimethyl sulfoxide (DMSO). Examples of suitable bases are sodium hydroxide, potassium hydroxide, and potassium carbonate. In the case of polysulfone (PSE) synthesis, the reaction is a two-step process in which the dialkah metal salt of bisphenol A (1) is first formed in situ from bisphenol A [80-05-7] by reaction with the base (eg, two molar equivalents of NaOH),... 

DMSO is an effective solvent for the polymerization as it affords good solubiUty for both the polymer and disodium bisphenol A [2444-90-8]. Typical polymerization temperatures for polysulfone are in the range 130—160°C. At temperatures below 130°C, the polymerization slows down considerably due to poor solubiUty of the disodium bisphenol A salt. 

The reaction of NaOH with bisphenol A generates water. This water must be thoroughly removed from the system to allow the reaction to be driven to completion, and more importandy, to preclude any residual water in the system from hydrolyzing part of the DCDPS monomer (2). Before the introduction of DCDPS for the polymerization step, all but traces of water must be removed. Failure to do so results in regeneration of NaOH, which rapidly reacts with DCDPS to form the monosodium salt of 4-chloro-4 -hydroxydiphenylsulfone [18995-09-0] (3) (6). 

NMP are examples of suitable solvents for PES and PPSF polymerizations. Chlorobenzene or toluene are used as cosolvents at low concentrations. These cosolvents form an azeotrope with water as they distill out of the reaction mixture, thereby keeping the polymerization medium dehydrated. Potassium carbonate is a suitable choice for base. The synthesis of PES and PPSE differ from the PSE case in that the reaction is carried out in a single-step process. In other words, the formation of the dipotassium salt of the bisphenol is not completed in a separate first step. Equations 2 and 3 represent polymerizations based on the dipotassium salts of bisphenol S and biphenol to make PES and PPSE, respectively. 

Other Accelerators. Amine isophthalate and thiazolidine thione, which are used as alternatives to thioureas for cross-linking polychloroprene (Neoprene) and other chlorine-containing polymers, are also used as accelerators. A few free amines are used as accelerators of sulfur vulcanization these have high molecular weight to minimize volatility and workplace exposure. Several amines and amine salts are used to speed up the dimercapto thiadiazole cure of chlorinated polyethylene and polyacrylates. Phosphonium salts are used as accelerators for the bisphenol cure of fluorocarbon mbbers. 

Quinone dioximes, alkylphenol disulfides, and phenol—formaldehyde reaction products are used to cross-link halobutyl mbbers. In some cases, nonhalogenated butyl mbber can be cross-linked by these materials if there is some other source of halogen in the formulation. Alkylphenol disulfides are used in halobutyl innerliners for tires. Methylol phenol—formaldehyde resins are used for heat resistance in tire curing bladders. Bisphenols, accelerated by phosphonium salts, are used to cross-link fluorocarbon mbbers. 

Solvent for Displacement Reactions. As the most polar of the common aprotic solvents, DMSO is a favored solvent for displacement reactions because of its high dielectric constant and because anions are less solvated in it (87). Rates for these reactions are sometimes a thousand times faster in DMSO than in alcohols. Suitable nucleophiles include acetyUde ion, alkoxide ion, hydroxide ion, azide ion, carbanions, carboxylate ions, cyanide ion, hahde ions, mercaptide ions, phenoxide ions, nitrite ions, and thiocyanate ions (31). Rates of displacement by amides or amines are also greater in DMSO than in alcohol or aqueous solutions. Dimethyl sulfoxide is used as the reaction solvent in the manufacture of high performance, polyaryl ether polymers by reaction of bis(4,4 -chlorophenyl) sulfone with the disodium salts of dihydroxyphenols, eg, bisphenol A or 4,4 -sulfonylbisphenol (88). These and related reactions are made more economical by efficient recycling of DMSO (89). Nucleophilic displacement of activated aromatic nitro groups with aryloxy anion in DMSO is a versatile and useful reaction for the synthesis of aromatic ethers and polyethers (90). 

It is prepared from the polycondensation of the disodium salt of bisphenol A and 4,4-dichlorodiphenyl sulfone in a polar aprotic solvent such as dimethyl sulfoxide (26). 

The terminal R groups can be aromatic or aliphatic. Typically, they are derivatives of monohydric phenoHc compounds including phenol and alkylated phenols, eg, /-butylphenol. In iaterfacial polymerization, bisphenol A and a monofunctional terminator are dissolved in aqueous caustic. Methylene chloride containing a phase-transfer catalyst is added. The two-phase system is stirred and phosgene is added. The bisphenol A salt reacts with the phosgene at the interface of the two solutions and the polymer "grows" into the methylene chloride. The sodium chloride by-product enters the aqueous phase. Chain length is controlled by the amount of monohydric terminator. The methylene chloride—polymer solution is separated from the aqueous brine-laden by-products. The facile separation of a pure polymer solution is the key to the interfacial process. The methylene chloride solvent is removed, and the polymer is isolated in the form of pellets, powder, or slurries. 

The resins are made by batch processes employing Friedel-Crafts reactions or nucleophilic aromatic substitution. Udel resin and Radel R resin are produced by the nucleophilic displacement of chloride on 4,4 -dichlorodiphenyl sulfone by the potassium salts of bisphenol A and 4,4 -biphenol, respectively (97) ... 

Dehydrofluorination by primary and secondary aliphatic amines occurs at room temperature and is the basis of diamine cross linkmg, which occurs by dehydrofluonnation and subsequent nucleophihc substitution of the double bond The locus of dehydrofluonnation is a VDF unit flanked by two perfluoroolefin units This selectively base-sensitive methylene group also undergoes elimination as the first step in phase-transfer-catalyzed cross-hnking with quaternary ammo mum or phosphomum salts, bisphenols, and morganic oxides and hydroxides as HF acceptors [31, 32]... 

Chemical Name 4,4 -(2-pyridinylmethylene)bisphenol bis(hydrogen sulfate) (ester) disodium salt... 

Polycarbonates (PC) are another group of condensation thermoplastics used mainly for special engineering purposes. These polymers are considered polyesters of carbonic acid. They are produced by the condensation of the sodium salt of bisphenol A with phosgene in the presence of an organic solvent. Sodium chloride is precipitated, and the solvent is removed by distillation ... 

Polyether sulfones can be prepared by the reaction of the sodium or potassium salt of bisphenol A and 4,4-dichlorodiphenyl sulfone. Bisphenol A acts as a nucleophile in the presence of the deactivated aromatic ring of the dichlorophenylsulfone. The reaction may also be catalyzed with Friedel-Crafts catalysts the dichlorophenyl sulfone acts as an electrophile ... 

Epoxy adhesives are prepared in two steps. S -2 reaction of the disodium salt of bisphenol A with cpichlorohydrin forms a "prepolymer," which is then "cured" by treatment with a triaminc such as I-I2NCH2CH2NHCH2CH2NEI2-... 

The reaction generates easily oxidizable alkali phenates. Thus, the polymerization must be conducted in an inert atmosphere. The sodium and potassium salts of the bisphenols are widely used because they are more soluble in polar aprotic solvents. 

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