Bisphenol methylene chloride reaction

Preparation of siloxane-carbonate segmented copolymers by interfacial polymerization involves the reaction of carboxypropyl-terminated siloxane oligomers with bisphenol-A and phosgene, in the presence of a strong base and a phase transfer catalyst, in water/methylene chloride solvent system l50 192), as shown in Reaction Scheme XIV. 

The reaction between a dihydroxy compound (bisphenol) and phosgene, which is performed on an industrial scale, proceeds even at room temperature.The reaction is generally carried out in a biphasic medium consisting of methylene chloride (with dissolved phosgene) and aqueous sodium hydroxide (with dissolved bisphenol sodium salt) and a phase transfer catalyst (e.g.triethylamine).The procedure is termed interfacial polycondensation (see Sect.4.1.2.3 and Examples 4-5,4-12,and 4-13). 

Syntheses of Bisphenol-A Carbonate Oligomers in Aqueous Caustic. Oligomers made by the aqueous caustic method were made in an apparatus identical with that used in the interfacial method experimental conditions were similar. Methylene chloride, though, was not added to the reaction mixture. The product precipitated on formation and was isolated by filtration. 

The preparative method used in these syntheses and in the scaleup evaluation was a two-step sequential batch technique (Figure 6) (see Experimental). BPDSC and bisphenol A, both sparingly soluble, were suspended in methylene chloride. No reaction occurred until the acid acceptor was added slowly to this mixture. Once the initial exothermic... 

Today, most polycarbonate is produced by an interfacial adaptation of the reaction in equation 4 (7 ). The bisphenol plus 1-3 raol% monofunctional phenol, which controls molecular weight, is dissolved or slurried in aqueous sodium hydroxide methylene chloride is added as a polymer solvent, a tertiary amine is added as a catalyst, and phosgene gas is dispersed in the rapidly stirred mixture. Additional caustic solution is added as needed to maintain basicity. The growing polymer dissolves in the methylene chloride, and the phenolic content of the aqueous phase diminishes. 

Polycarbonates are synthesized by interfacial polycondensation of bisphenol A and phosgene. The reaction is conducted in methylene chloride/water, and sodium hydroxide is used as a hydrogen chloride scavenger. Polycarbonates can also be synthesized by means of solution polymerization, using pyridine as the... 

Copolymerizations were carried out interfacially in a laboratory Waring blender. A typical reaction was conducted as follows To a stirred solution of 1.5 g sodium hydroxide in 200 ml water in the blender was added 3.500 g of bisphenol-A. Then, 2.0 g tetraethyl ammonium chloride was added, followed by 150 mJl of methylene cjiloride. A solution of 9.900 g of a -10,000 gm/mole (Mn) polysulfone oligomer in 100 ml methylene chloride was then introduced. Next, a solution of 3.3172 g of terephthaloyl chloride in 100 mH of methylene chloride was added to the reaction mixture and stirred vigorously. Agitation was stopped after approximately 5 minutes of... 

In this method a solution of bisphenol A in aqueous sodium hydroxide is dispersed in an organic solvent such as methylene chloride by rapid stirring. A small quantity of tertiary amine (e.g., triethylamine) or quaternary ammonium base (e.g., tetramethylammonium hydroxide) is added to the system as catalyst and then phosgene is passed in at about 25°C. When reaction is complete the organic phase, which contains the polymer, is separated and the polymer is isolated as in the solution method described above. 

As expected, there are some interesting blends that do not fit the classifications chosen for this chapter and will be summarized in this section. PHE/PVME blends were shown to be miscible with lest behavior observed [ 180]. Partial methylation or benzylation of the secondary hydroxyls of PHE lowered the position of the lest and thus reduced the inherent miscibihty [1140]. PHE was also shown to exhibit miscibility with poly(4-vinyl pyridine), presumably due to the hydrogen bonding potential expected from this combination [223]. The polyformal from the reaction product of tetramethyl Bisphenol S and methylene chloride was foimd to be miscible with styrene-acrylonitrile copolymers (24, 28 and 42 wt% AN) and also poly(vinyl chloride) [1141]. 

Aromatic polycarbonates are prepared from various bisphenols, the most widely used being bisphenol A. The synthesis of aromatic polycarbonates is based on the reaction of bisphenol with carbonic acid derivatives such as phosgene, diphosgene, carbonic acid esters and chloroformic acid esters. The most important process for production of aromatic polycarbonate is the so-called interfacial process , first developed by Bayer. In this process, bisphenol A is phosgenated in the presence of methylene chloride in controlled conditions. 

Another method for the polycondensation involves the reaction between COCI2 and bisphenol A in methylene chloride solution in the presence of pyridine to trap the HCl produced. 

In the interfacial process, bisphenol A is dissolved in the aqueous sodium hydroxide phase of a two-phase system with methylene chloride. As phosgene is pumped into the mixture, the sodium chloride condensation by-product dissolves in the aqueous phase, and the growing polymer dissolves in the organic phase. A tertiary amine is used as the catalyst. When the reaction is complete, the methylene chloride solution is extracted with acid to remove basic components and then washed with water. The solvent is then flashed off and recycled, leaving the solid. 

Hay and co-workers (5,(5) described the preparation of poly-formals from the reaction of bisphenols and excess methylene chloride with sodium hydroxide or potassium hydroxide in the... 

---