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Hans R Kricheldorf - One of the best experts on this subject based on the ideXlab platform.
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Copolycarbonates of isosorbide and various diols
Journal of Polymer Science Part A: Polymer Chemistry, 2006Co-Authors: Saber Chatti, Hans R Kricheldorf, Gert SchwarzAbstract:Isosorbide and equimolar amounts of various diols were polycondensed with Diphosgene and pyridine. Bisphenol A, 3,3′-dimethyl bisphenol A, bisphenol C, 1,3-bis(4-hydroxybenzoyloxy)propane, and 1,4-cyclohexane diol were used as comonomers. The compositions were determined by 1H NMR spectroscopy; the random sequences were characterized by 13C NMR spectroscopy. For the high-molar-mass copolycarbonates of bisphenol A, 3,3′-dimethyl bisphenol A, and bisphenol C, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry proved that the chain growth was mainly limited by cyclization. Copolycarbonates with alternating sequences were obtained by the polycondensation of bisphenol A with isosorbide bischloroformiate or from isosorbide and bisphenol A bischloroformiate. In these cases, large amounts of cyclic oligo- and polycarbonates were also formed. The glass-transition temperatures were determined by differential scanning calorimetry measurements. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3616–3628, 2006
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Cyclic and Noncyclic Polycarbonates of Isosorbide (1,4:3,6-Dianhydro-d-glucitol)
Macromolecules, 2006Co-Authors: Saber Chatti, Gert Schwarz, Hans R KricheldorfAbstract:Three different synthetic methods were studied with respect to their usefulness for the preparation of poly(isosorbide carbonate) (PIC). Thermal polycondensations of isosorbide with dimethyl- or diethyl carbonate in bulk proved unsuccessful, regardless of the transesterification catalyst. Polycondensations of isosorbide with Diphosgene in pyridine gave polycarbonates, the molecular weights of which depended largely on the excess of Diphosgene. In all experiments, OH-terminated linear chains were the main products. Similar results were obtained from pyridine-promoted phosgenations in dioxane. However, polycondensations of equimolar mixtures of isosorbide and isomannide mainly yielded cyclic polymers. Pyridine-promoted polycondensations of isosorbide with isosorbide bischloroformate only gave low molar mass polycarbonates. At low temperatures, even-numbered linear chains were the main products, but higher temperatures gave even-numbered cycles. SEC measurements with triple detection evidenced the formation ...
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Polycondensations of Bisphenol-A with Diphosgene or Triphosgene in Water-Free Organic Solvents†
Macromolecular Chemistry and Physics, 2005Co-Authors: Hans R Kricheldorf, Sigrid Böhme, Gert SchwarzAbstract:Bisphenol-A was polycondensed with Diphosgene and excess pyridine in a mixture of dry dichloromethane and 1,4-dioxane. The stoichiometry was varied to optimize the molecular weight. According to MALDI-TOF mass spectra thefraction of cyclic polycarbonates increased with higher molecular weights. Analogous results were obtained with triphosgene. When pyridine was replaced by triethylamine, diethyl carbamoyl chloride was formed and an excess of Diphosgene (plus triethylamine) yielded polycarbonates having one or two diethylcarbamate endgroups. However, the content of cycles increased again with the molecular weight and peaked for the sample with the maximum molecular weight. 1 H NMR endgroup analyses confirmed the interpretation of the MALDI-TOF mass spectra. SEC measurement indicated high polydispersity indices (around 7) for samples rich in cycles.
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Syntheses of cyclic polycarbonates by the direct phosgenation of bisphenol M
Journal of Polymer Science Part A: Polymer Chemistry, 2005Co-Authors: Hans R Kricheldorf, Gert Schwarz, Sigrid Böhme, Claus-ludolf SchultzAbstract:Bisphenol M was subjected to interfacial polycondensations in an NaOH/CH2Cl2 system with triethylamine as a catalyst. Regardless of the catalyst concentration, similar molecular weights were obtained, and matrix-assisted laser desorption/ionization time-of-flight mass spectra exclusively displayed mass peaks of cycles (detectable up to 15,000 Da). With triethyl benzyl ammonium chloride as a catalyst, linear chains became the main products, but the contents of the cycles and the molecular weights strongly increased with higher catalyst/bisphenol ratios. When the pseudo-high-dilution method was applied, both Diphosgene and triphosgene yielded cyclic polycarbonates of low or moderate molecular weights. Size exclusion chromatography measurements, evaluated with the triple-detection method, yielded bimodal mass distribution curves with polydispersities of 5–12. Furthermore, a Mark–Houwink equation was elaborated, and it indicated that the hydrodynamic volume of poly(bisphenol M carbonate) was quite similar to that of poly(bisphenol A carbonate)s with similar concentrations of cyclic species. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1248–1254, 2005
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Polymers of carbonic acid 32: Influence of catalysts on propagation and cyclization in the interfacial polycondensation of Bisphenol A with Diphosgene
Journal of Polymer Science Part A: Polymer Chemistry, 2003Co-Authors: Hans R Kricheldorf, Gert Schwarz, Sigrid Böhme, Claus-ludolf SchultzAbstract:Bisphenol A was polycondensed with Diphosgene in a dichloromethane/ aqueous NaOH system. Temperature, time, and molar ratios of the reactants were optimized according to a previously elaborated optimization of the hydrolytic polycondensation of bisphenol A bischloroformate. Five of the following catalysts were examined: triethylamine, 4-(N,N-dimethylamino)pyridine (DMAP), ethyldiisopropylamine (EDPA), tetrabutylammonium hydrogen sulfate, and triethylbenzylammonium chloride (TEBA-Cl). Triethylamine and DMAP accelerated the hydrolysis of Diphosgene by formation of a hydrophilic acylammonium salt. Therefore, the molecular weights decreased with higher concentration of these tert-amines. However, the molecular weights increased (weight-average molecular weight up to 10 6 ) with higher concentrations of tetraalkylammonium salts because these catalysts favor chain growth in the organic phase via naked phenoxide ions without catalyzing the hydrolysis of Diphosgene. EDPA gave poor results under all circumstances. Cyclic polycarbonates were discovered in all samples. Their fraction increased with the average molecular weight of the samples. When samples prepared with triethylamine or TEBA-Cl were fractionated, cycles having molar masses up to 15,000 Da were detected by matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy.
Pierre-alexandre Glaude - One of the best experts on this subject based on the ideXlab platform.
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Thermal Decomposition of Phosgene and Diphosgene
Journal of Physical Chemistry A, 2018Co-Authors: J.-c. Lizardo-huerta, Baptiste Sirjean, L. Verdier, René Fournet, Pierre-alexandre GlaudeAbstract:Phosgene (COCl2) is a toxic compound used or formed in a wide range of applications. The understanding of its thermal decomposition for destruction processes or in the event of accidental fire of stored reserves is a major safety issue. In this study, a detailed chemical kinetic model for the thermal decomposition and combustion of phosgene and Diphosgene is proposed for the first time. A large number of thermo-kinetic parameters were calculated using quantum chemistry and reaction rate theory. The model was validated against experimental pyrolysis data from the literature. It is predicted that the degradation of Diphosgene is mainly ruled by a pericyclic reaction producing two molecules of phosgene, and, to a lesser extent, by a roaming radical reaction yielding CO2 and CCl4. Phosgene is much more stable than Diphosgene under high-temperature conditions and its decomposition starts at higher temperatures. Decomposition products are CO and Cl2. An equimolar mixture of these latter can be considered as a surrogate of phosgene from the kinetic point of view, but the important endothermic effect of the decomposition reaction can lead to different behaviors, for instance in case of auto-ignition under high pressure and high temperature.
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Thermal Decomposition of Phosgene and Diphosgene
The journal of physical chemistry. A, 2017Co-Authors: J.-c. Lizardo-huerta, Baptiste Sirjean, L. Verdier, René Fournet, Pierre-alexandre GlaudeAbstract:Phosgene (COCl2) is a toxic compound used or formed in a wide range of applications. The understanding of its thermal decomposition for destruction processes or in the event of accidental fire of stored reserves is a major safety issue. In this study, a detailed chemical kinetic model for the thermal decomposition and combustion of phosgene and Diphosgene is proposed for the first time. A large number of thermo-kinetic parameters were calculated using quantum chemistry and reaction rate theory. The model was validated against experimental pyrolysis data from the literature. It is predicted that the degradation of Diphosgene is mainly ruled by a pericyclic reaction producing two molecules of phosgene and, to a lesser extent, by a roaming radical reaction yielding CO2 and CCl4. Phosgene is much more stable than Diphosgene under high-temperature conditions, and its decomposition starts at higher temperatures. Decomposition products are CO and Cl2. An equimolar mixture of the latter molecules can be considere...
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Thermal Decomposition of Phosgene and Diphosgene
2017Co-Authors: J.-c. Lizardo-huerta, Baptiste Sirjean, L. Verdier, René Fournet, Pierre-alexandre GlaudeAbstract:Phosgene (COCl2) is a toxic compound used or formed in a wide range of applications. The understanding of its thermal decomposition for destruction processes or in the event of accidental fire of stored reserves is a major safety issue. In this study, a detailed chemical kinetic model for the thermal decomposition and combustion of phosgene and Diphosgene is proposed for the first time. A large number of thermo-kinetic parameters were calculated using quantum chemistry and reaction rate theory. The model was validated against experimental pyrolysis data from the literature. It is predicted that the degradation of Diphosgene is mainly ruled by a pericyclic reaction producing two molecules of phosgene and, to a lesser extent, by a roaming radical reaction yielding CO2 and CCl4. Phosgene is much more stable than Diphosgene under high-temperature conditions, and its decomposition starts at higher temperatures. Decomposition products are CO and Cl2. An equimolar mixture of the latter molecules can be considered as a surrogate of phosgene from the kinetic point of view, but the important endothermic effect of the decomposition reaction can lead to different behaviors, for instance, in the case of autoignition under high pressure and high temperature
J.-c. Lizardo-huerta - One of the best experts on this subject based on the ideXlab platform.
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Thermal Decomposition of Phosgene and Diphosgene
Journal of Physical Chemistry A, 2018Co-Authors: J.-c. Lizardo-huerta, Baptiste Sirjean, L. Verdier, René Fournet, Pierre-alexandre GlaudeAbstract:Phosgene (COCl2) is a toxic compound used or formed in a wide range of applications. The understanding of its thermal decomposition for destruction processes or in the event of accidental fire of stored reserves is a major safety issue. In this study, a detailed chemical kinetic model for the thermal decomposition and combustion of phosgene and Diphosgene is proposed for the first time. A large number of thermo-kinetic parameters were calculated using quantum chemistry and reaction rate theory. The model was validated against experimental pyrolysis data from the literature. It is predicted that the degradation of Diphosgene is mainly ruled by a pericyclic reaction producing two molecules of phosgene, and, to a lesser extent, by a roaming radical reaction yielding CO2 and CCl4. Phosgene is much more stable than Diphosgene under high-temperature conditions and its decomposition starts at higher temperatures. Decomposition products are CO and Cl2. An equimolar mixture of these latter can be considered as a surrogate of phosgene from the kinetic point of view, but the important endothermic effect of the decomposition reaction can lead to different behaviors, for instance in case of auto-ignition under high pressure and high temperature.
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Thermal Decomposition of Phosgene and Diphosgene
The journal of physical chemistry. A, 2017Co-Authors: J.-c. Lizardo-huerta, Baptiste Sirjean, L. Verdier, René Fournet, Pierre-alexandre GlaudeAbstract:Phosgene (COCl2) is a toxic compound used or formed in a wide range of applications. The understanding of its thermal decomposition for destruction processes or in the event of accidental fire of stored reserves is a major safety issue. In this study, a detailed chemical kinetic model for the thermal decomposition and combustion of phosgene and Diphosgene is proposed for the first time. A large number of thermo-kinetic parameters were calculated using quantum chemistry and reaction rate theory. The model was validated against experimental pyrolysis data from the literature. It is predicted that the degradation of Diphosgene is mainly ruled by a pericyclic reaction producing two molecules of phosgene and, to a lesser extent, by a roaming radical reaction yielding CO2 and CCl4. Phosgene is much more stable than Diphosgene under high-temperature conditions, and its decomposition starts at higher temperatures. Decomposition products are CO and Cl2. An equimolar mixture of the latter molecules can be considere...
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Thermal Decomposition of Phosgene and Diphosgene
2017Co-Authors: J.-c. Lizardo-huerta, Baptiste Sirjean, L. Verdier, René Fournet, Pierre-alexandre GlaudeAbstract:Phosgene (COCl2) is a toxic compound used or formed in a wide range of applications. The understanding of its thermal decomposition for destruction processes or in the event of accidental fire of stored reserves is a major safety issue. In this study, a detailed chemical kinetic model for the thermal decomposition and combustion of phosgene and Diphosgene is proposed for the first time. A large number of thermo-kinetic parameters were calculated using quantum chemistry and reaction rate theory. The model was validated against experimental pyrolysis data from the literature. It is predicted that the degradation of Diphosgene is mainly ruled by a pericyclic reaction producing two molecules of phosgene and, to a lesser extent, by a roaming radical reaction yielding CO2 and CCl4. Phosgene is much more stable than Diphosgene under high-temperature conditions, and its decomposition starts at higher temperatures. Decomposition products are CO and Cl2. An equimolar mixture of the latter molecules can be considered as a surrogate of phosgene from the kinetic point of view, but the important endothermic effect of the decomposition reaction can lead to different behaviors, for instance, in the case of autoignition under high pressure and high temperature
Silvia Mantovani - One of the best experts on this subject based on the ideXlab platform.
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Conversion of Bis(trichloromethyl) Carbonate to Phosgene and Reactivity of Triphosgene, Diphosgene, and Phosgene with Methanol1
The Journal of organic chemistry, 2000Co-Authors: Lucia Pasquato, Giorgio Modena, Livius Cotarca, Pietro Delogu, Silvia MantovaniAbstract:Triphosgene was decomposed quantitatively to phosgene by chloride ion. The reaction course was monitored by IR spectroscopy (React-IR), showing that Diphosgene was an intermediate. The methanolysis of triphosgene in deuterated chloroform, monitored by proton NMR spectroscopy, gave methyl chloroformate and methyl 1,1,1-trichloromethyl carbonate in about a 1:1 ratio, as primary products. The reaction carried out in the presence of large excess of methanol (0.3 M, 30 equiv) was a pseudo-first-order process with a kobs of 1.0 × 10-4 s-1. Under the same conditions, values of kobs of 0.9 × 10-3 s-1 and 1.7 × 10-2 s-1 for the methanolysis of Diphosgene and phosgene, respectively, were determined. The experimental data suggest that, under these conditions, the maximum concentration of phosgene during the methanolysis of triphosgene and Diphosgene was lower than 1 × 10-5 M. Methyl 1,1,1-trichloromethyl carbonate was synthesized and characterized also by the APCI-MS technique.
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conversion of bis trichloromethyl carbonate to phosgene and reactivity of triphosgene Diphosgene and phosgene with methanol 1
Journal of Organic Chemistry, 2000Co-Authors: Lucia Pasquato, Giorgio Modena, Livius Cotarca, Pietro Delogu, Silvia MantovaniAbstract:Triphosgene was decomposed quantitatively to phosgene by chloride ion. The reaction course was monitored by IR spectroscopy (React-IR), showing that Diphosgene was an intermediate. The methanolysis of triphosgene in deuterated chloroform, monitored by proton NMR spectroscopy, gave methyl chloroformate and methyl 1,1, 1-trichloromethyl carbonate in about a 1:1 ratio, as primary products. The reaction carried out in the presence of large excess of methanol (0.3 M, 30 equiv) was a pseudo-first-order process with a k(obs) of 1.0 x 10(-)(4) s(-)(1). Under the same conditions, values of k(obs) of 0.9 x 10(-)(3) s(-)(1) and 1.7 x 10(-)(2) s(-)(1) for the methanolysis of Diphosgene and phosgene, respectively, were determined. The experimental data suggest that, under these conditions, the maximum concentration of phosgene during the methanolysis of triphosgene and Diphosgene was lower than 1 x 10(-)(5) M. Methyl 1,1,1-trichloromethyl carbonate was synthesized and characterized also by the APCI-MS technique.
R Gourhan - One of the best experts on this subject based on the ideXlab platform.
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thermal decomposition of chloropicrin Diphosgene and phosgene between 100 and 530 c
Journal of Analytical and Applied Pyrolysis, 2000Co-Authors: Frederique Battinleclerc, François Baronnet, G Paternotte, J.p. Leclerc, R GourhanAbstract:Abstract The gas-phase pyrolysis of chloropicrin, Diphosgene and phosgene has been investigated in a static reactor at temperatures between 100 and 530°C, at an initial pressure of 25 torr and for reaction times ranging from 10 to 120 min. Phosgene is the main carbon containing reaction product of the pyrolyses of chloropicrin and Diphosgene and its decomposition leads to the formation of carbon monoxide and chlorine. A kinetic scheme for the decomposition of phosgene has been proposed and has permitted satisfactory modelling of the experimental results obtained. The study clearly shows the possible industrial use of this process to destroy chemical weapons and a first range of temperatures and reaction times has been selected for future reactor design.
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Thermal decomposition of chloropicrin, Diphosgene and phosgene between 100 and 530°C
Journal of Analytical and Applied Pyrolysis, 2000Co-Authors: Frédérique Battin-leclerc, François Baronnet, G Paternotte, J.p. Leclerc, R GourhanAbstract:Abstract The gas-phase pyrolysis of chloropicrin, Diphosgene and phosgene has been investigated in a static reactor at temperatures between 100 and 530°C, at an initial pressure of 25 torr and for reaction times ranging from 10 to 120 min. Phosgene is the main carbon containing reaction product of the pyrolyses of chloropicrin and Diphosgene and its decomposition leads to the formation of carbon monoxide and chlorine. A kinetic scheme for the decomposition of phosgene has been proposed and has permitted satisfactory modelling of the experimental results obtained. The study clearly shows the possible industrial use of this process to destroy chemical weapons and a first range of temperatures and reaction times has been selected for future reactor design.