Synthesis of the polyformal of bisphenol A

Hay, Allan S.; Williams, Frank J.; Relles, Howard M.; Boulette, Bernice; Donahue, P. E.; Johnson, Douglas S.

doi:10.1002/pol.1983.130210609

Cited by 38 publications

(14 citation statements)

References 2 publications

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“…In 1976, Dehmlow and Schmidt2 reported the synthesis of a series of dialkly and diaryl formals from the reaction of alkoxide and phenoxide anions with methylene chloride in the presence of a phase‐transfer catalyst (PTC). Following this model reaction, Hay et al3 reported that the 4,4′‐isopropylidenediphenol (BPA)‐type polyformal can be readily synthesized from BPA, sodium hydroxide, and methylene chloride. From this synthesis route, high molecular weight polyformals have been prepared without the use of dangerous phosgene.…”

Section: Introductionmentioning

confidence: 99%

Results of the Jostent coronary stent graft implantation in various clinical settings: Procedural and follow‐up results

Gercken

Lansky

Buellesfeld

et al. 2002

Cathet Cardio Intervent

146

136

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The Jostent coronary stent graft (CSG) is composed of a PTFE layer sandwiched between two stainless steel stents, initially introduced for the treatment of coronary perforations and aneurysms with excellent results. By providing a mechanical barrier, this stent design also may be beneficial in the treatment of complex ulcerated lesions and in-stent restenosis by preventing debris protrusion and neointimal proliferation through the stent struts. To evaluate the safety and efficacy of this stent graft, we implanted 78 CSGs in 70 patients for a broad range of indications, including coronary perforations, aneurysms, degenerated saphenous vein grafts, complex lesions, and in-stent restenosis. The primary angiographic success rate (95.9%) was high, and using intravascular ultrasound (IVUS) guidance during stent implantation and high inflation pressures (19.3 +/- 3.2 atm), stent expansion with optimal symmetry was achieved in 94.7%. One limitation of the Jostent CSG was the side-branch occlusion rate (18.6%) and the resulting non-Q-wave infarction rate in seven cases (mean CK elevation, 238 U/l), acute Q-wave MI in two cases, and transient ventricular fibrillation in one patient after occlusion of the proximal RCA side branch without further complications. Subacute stent thrombosis occurred in four cases (5.7%) 7 to 70 days after stent implantation, despite using combined antiplatelet therapy with aspirin (ASA), ticlopidine, and/or clopidogrel for 30 days. Angiographic follow-up was available in 56 patients (80.0%) after a mean of 159 +/- 49 days, and follow-up IVUS was available in 38 cases. The overall restenosis rate (> 50% diameter stenosis) was 31.6% manifest primarily as edge restenosis (29.8% stent edge vs. 8.8% stent center; P < 0.001). IVUS examinations showed a minimal late lumen loss of 0.4 +/- 2.2 mm(2) within the center of the stent graft vs. 3.2 +/- 2.3 mm(2) at the stent edges (P < 0.001). The restenosis rate in the prespecified subgroups was 33.3% for saphenous vein grafts (2/6 lesions), 30.0% in complex lesions (6/20 lesions), and 38.5% (10/26 lesions) for the treatment of in-stent restenosis. Implantation of the Jostent CSG is feasible and safe, even in complex lesion subsets, and is associated with high primary success rates provided major side branches are avoided. The use of this stent may require an extended time course of antiplatelet therapy. Frequent focal stent edge renarrowing influences the overall restenosis rate. However, in treatment of complex in-stent restenosis and vein graft lesions, stent grafts may offer benefit over conventional therapies. Covered stents such as the JoMed coronary stent graft may become essential for bailout treatment of coronary perforations.

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Section: Introductionmentioning

confidence: 99%

Results of the Jostent coronary stent graft implantation in various clinical settings: Procedural and follow‐up results

Gercken

Lansky

Buellesfeld

et al. 2002

Cathet Cardio Intervent

146

136

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“…A low molecular weight coupling reagent is added to a mixture of poly(phenylene oxide) and a second homopolymer with phenolic hydroxyl endgroups such as 7 (9) or 8 (10) in the presence of sodium hydroxide and catalyst. The resultant copolymer from 1 and 8 has two glass transition temperatures (T 's at 97° and 202°) which indicates two phases are present.…”

Section: White and Loucksmentioning

confidence: 99%

Coupling and Capping Reactions on Poly(2,6-dimethyl-1,4-phenylene Oxide)

White

Loucks

1985

ACS Symposium Series

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The phenolic hydroxy1 endgroups in poly(2,6-dimethyl -1,4-phenylene oxide) react with various mono, di-and trifunctional acylating (or related) reagents under phase transfer catalysis conditions to produce capped and/or coupled products in high yields. Acetic anhy dride, even at low concentrations, acetylated the hydroxyl endgroups almost quantitatively. Bifunctional reagents (e.g., isophthaloyl chloride) coupled the polymer producing a viscosity increase consistent with a two-fold increase in molecular weight. Trifunctional reagents (e.g., phosphorous oxychloride) produced a branched polymer and tripled the molecular weight. Typical increases in intrinsic viscosity of the polymer with trifunctional coupling were from 0.25 d1/g to 0.50 d1/g. With bifunctional poly(phenylene oxide)s, even larger molecular weight increases were attained. Quaternary ammoni um and phosphonium halides were used as the phase transfer catalysts. For effective cou pling, high-shear mixing and high concentrations of polymer and base were used.The terminal phenolic groups of oligomers of poly(2,6-dimethyl-l,4-phenylene oxide), 1, (1, 2) react efficiently with multifunctional coupling reagents to form polymers with increased molecular weights. A high degree of coupling has been attained by adding a stoichiometric quantity of a coupling reagent such as phthaloyl chloride under anhydrous conditions to the preformed anion of the phenolic hydroxyl end group of the polymer.(3) A more convenient procedure which utilizes phase transfer catalysis (PTC) (4-6) and does not require anhydrous conditions or exact stoichiometric ratios of reactants is described in this report. The reaction is of the general type:0097-6156/85/0282-0187$06.00/0

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“…6 Structurally related aromatic polyformal has been obtained from bisphenol A and dichloromethane. 7,8 This polymer also has prominent physical properties comparable to those of bisphenol A-based polycarbonate. 7,8 One of us has already reported on the preparation and characterization of a series of hexafluoroisopropylidene-group-containing polycarbonates 9 and polyformals 10 derived from 2,2-bis(4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane (bisphenol AF), bisphenol A, or both.…”

Section: Introductionmentioning

confidence: 97%

“…7,8 This polymer also has prominent physical properties comparable to those of bisphenol A-based polycarbonate. 7,8 One of us has already reported on the preparation and characterization of a series of hexafluoroisopropylidene-group-containing polycarbonates 9 and polyformals 10 derived from 2,2-bis(4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane (bisphenol AF), bisphenol A, or both. The physical properties of bisphenol Abased polycarbonate and polyformal, such as their solubility, mechanical, surface, and optical properties, and thermal stability, were successfully improved by fluorine substitution.…”

Section: Introductionmentioning

confidence: 97%