ChemInformVolume 30, Issue 18 Preparative Organic Chemistry ChemInform Abstract: Syntheses and Properties of O-Fluoro Alkyl N,N′-Dialkyl Isoureas. L. Badache, L. Badache Lab. Chim. Appl., CNRS, Ec. Natl. Super. Chim., F-34296 Montpellier, Fr.Search for more papers by this authorG. Bauduin, G. Bauduin Lab. Chim. Appl., CNRS, Ec. Natl. Super. Chim., F-34296 Montpellier, Fr.Search for more papers by this authorB. Boutevin, B. Boutevin Lab. Chim. Appl., CNRS, Ec. Natl. Super. Chim., F-34296 Montpellier, Fr.Search for more papers by this authorS. Rahal, S. Rahal Lab. Chim. Appl., CNRS, Ec. Natl. Super. Chim., F-34296 Montpellier, Fr.Search for more papers by this author L. Badache, L. Badache Lab. Chim. Appl., CNRS, Ec. Natl. Super. Chim., F-34296 Montpellier, Fr.Search for more papers by this authorG. Bauduin, G. Bauduin Lab. Chim. Appl., CNRS, Ec. Natl. Super. Chim., F-34296 Montpellier, Fr.Search for more papers by this authorB. Boutevin, B. Boutevin Lab. Chim. Appl., CNRS, Ec. Natl. Super. Chim., F-34296 Montpellier, Fr.Search for more papers by this authorS. Rahal, S. Rahal Lab. Chim. Appl., CNRS, Ec. Natl. Super. Chim., F-34296 Montpellier, Fr.Search for more papers by this author First published: 16 June 2010 https://doi.org/10.1002/chin.199918069Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. References L. Badache, G. Bauduin, B. Boutevin, S. Rahal, Syntheses and Properties of O-Fluoro Alkyl N,N′-Dialkyl Isoureas., J. Fluorine Chem., 1998, 92, 53-58. 10.1016/S0022-1139(98)00245-0 CASWeb of Science®Google Scholar Volume30, Issue18May 4, 1999 ReferencesRelatedInformation

The bulk radical copolymerization of tetrafluoroethylene (TFE) with 4,5,5-trifluoro-4-ene pentyl acetate (FAc), initiated by tert-butyl peroxypivalate to synthesize original, functionalized fluorinated poly(TFE-co-FAc), was investigated. FAc monomer was prepared from a five-step process. The copolymerization was carried out in batch at different initial monomer molar ratios ([TFE](o)/[FAc](o) ranging from 95/5 to 10/90 mol %) and at different initiator concentrations (ranging between 0.075 and 1.100 mol % about the monomers) at 70 degreesC. All the experiments revealed the production of fluorooligomers as evidenced by an allylic-transfer reaction from FAc. The microstructure of these copolymers (i.e., the molar percentage of both monomers in the copolymers) was assessed by F-19 NMR spectroscopy. From the kinetics of copolymerization, two key characteristics were determined. First, the reaction order to the initiator (being 1.07) and that of FAc monomer (0.85) showed a heterogeneous character of the copolymerization and monomolecular chain-transfer reaction to FAc. Second, from the Tidwell and Mortimer method, the reactivity ratios of both comonomers were determined, showing a tendency to alternance in a wide range of initial monomeric ratios (30/70-70/30): r(FAc) = 0.20 +/- 0.26 and r(TFE) = 0.18 +/- 0.15. Alfrey and Price's Q and e values of FAc were calculated by Greenley's technique [Q(FAc) = 0.098 (from Q(TFE) = 0.032) and e(FAc) = 1.23 (vs e(TFE) = 1.63)], indicating that FAc is a strong electron-withdrawing monomer as TFE. The normalized monomer-diad and triad fractions as a function of the polymer composition were obtained from the comonomer sequence-distribution procedure. The average molecular weights and molecular weight distributions as well as the thermal properties (glass-transition temperature and decomposition temperature) of the fluorocopolymers were assessed and are discussed. (C) 2004 Wiley Periodicals, Inc.

Diethanolamine and triethanolamine were selected among several low and high molecular weight polyols and amines tested as potential plasticizers of wheat gluten film. In comparison with glycerol, their use did not significantly affect the solubility in water, the opacity of the film (both increased very slightly) and the water vapor barrier properties. However, significant changes in mechanical properties were observed, i.e., increase in extensibility and elasticity. At 58% relative humidity (RH) and 20 g/100 g dry matter of di or triethanolamine, the elongation was five times higher than film plasticized with glycerol. At 98% RH, water appeared to compete with the amines to act as the plasticizer. Dynamic mechanical thermal analyses showed a glass transition temperature similar to that of the glycerol plasticized film. However, the observed broadening of thermal transition and the decrease in height of tanδ peak in the presence of amines, were related to differences in the type of the interactions with the proteins and to the basicity of the amino compounds.

Congenital tibial pseudarthrosis (CTP) remains one of the most challenging problems in paediatric orthopaedic surgery. With the abandonment of older grafting techniques in favor of vascularized fibular transplants or the Ilizarov method the final outcome has improved and made the prognosis for patients less cumbersome. Using the latter technique in 10 patients, a success rate of 90 % could be reached. Nevertheless, although solid healing occurs in most of the patients nowadays, this is often at the cost of multiple operations before a definite well united, equalized and normally aligned limb can be obtained.

Die kongenitale Tibiapseudarthrose (congenital tibial pseudarthrosis, CTP) ist und bleibt eine der größten Herausforderungen der operativen Kinderorthopädie. Nachdem ältere Transplantationstechniken zugunsten von vaskularisierten Fibulatransplantaten und der Methode nach Ilisarov, aufgegeben wurden, haben sich die Ergebnisse verbessert und die Prognose der Patienten ist aussichtsreicher geworden. Mit der neuesten Technik konnte bei 10 Patienten eine Erfolgsrate von 90 % erreicht werden. Obwohl bei den meisten Patienten heutzutage eine solide Ausheilung erreicht werden kann, bedarf es meist mehrfacher Operationen, bevor eine sicher zusammengewachsene, gleichlange und anatomisch korrekte Extremität erreicht werden kann.

Blends of poly(vinylidene fluoride) (PVDF) and some poly(vinyl alcohol-co-vinyl acetate) copolymers (PVAAc) with various molecular weights and acetate contents are studied by Fourier transform infrared spectroscopy (FTIR). First, two sets of blends of PVDF with two different copolymers at various concentrations are analysed. Then, 50/50 (wt/wt) blends of seven PVAAc with PVDF are studied. Two carbonyl bands are observed corresponding to free and bonded carbonyls. The rate of bonded carbonyls and the interaction enthalpies are determined. The results are in good agreement with the occurrence of a rather strong interaction between the carbonyls of the residual acetate groups and the hydroxyl groups of the copolymers. No interaction between the carbonyls and PVDF were observed. The experimental results are in a good agreement with the foresights of the Coleman–Graf–Painter interaction model.

Tetrafluoroethylene–propylene elastomers containing from 41 to 53mol% tetrafluoroethylene were prepared by emulsion copolymerization in batch operation, initiated by a redox system with tert-butylperoxybenzoate. Alternating copolymers in a wide range of monomer compositions were obtained. The composition curve has one azeotropic point at 46.7mol% tetrafluoroethylene. The reactivity ratio calculated from NMR and elemental analysis was found to be rTFE=0.014 and rP=0.18. Highly alternating structures of the copolymers synthesized were proved. Copolymer compositions calculated from NMR spectra correspond to those obtained by elemental analysis. The thermal properties were measured by DSC and TGA and discussed in connection with the copolymer structure.

Blends of poly(vinylidene fluoride) (PVDF) and some poly(vinyl alcohol–co-vinyl acetate) copolymers (PVAAc) with various molecular weights and acetate contents are studied by differential scanning calorimetry. First, two sets of blends of PVDF with two different PVAAc at various concentrations are analysed. Then, 50/50 (wt/wt) blends of each copolymer with PVDF are studied. Even though the glass transitions of both polymers are not observable, the PVDF melting and crystallization data give some indications about these blends: (1) the amorphous phases of both polymers seem to be, in any case, immiscible; (2) the crystallization of PVDF is modified by mixing with the copolymers (PVAAc), the most crystalline of them (with low acetate contents) improving its crystallinity ratio.

Bulk copolymerization of vinylidene fluoride (or 1,1-difluoroethylene (VDF)) with 4,5,5-trifluoro-4-ene pentyl acetate (FAc) initiated by di-tert-butyl peroxide is presented. A series of nine copolymerization reactions was investigated from initial [VDF] 0 /[FAc] 0 molar ratios ranging from 32/68 to 95/5. Both these comonomers copolymerized in this range of copolymerization. Moreover, these comonomers homopolymerized separately in these conditions. The copolymer compositions of these randomtype copolymers were calculated by means of 1 H and 19 F NMR spectroscopies and allowed one to quantify the respective amount of each monomeric unit in the copolymer. From the Tidwell and Mortimer method, the reactivity ratios, r i , of both comonomers were determined showing a higher incorporation of FAc in the copolymer (r FAc =3.26 ± 1.49 and r VDF = 0.17 ± 0.10 at 120 °C). Alfrey-Price's Q and e values of trifluorovinyl acetoxy monomer FAc were calculated to be 0.060 (from Q VDF = 0.008) or 0.040 (from Q VDF = 0.015) and +1.14 (vs e VDF = 0.40) or +1.23 (vs e VDF = 0.50), respectively, indicating that FAc is an electron-accepting monomer. The normalized monomer-diad and -triad fractions as a function of the polymer composition were obtained from the comonomer sequence distribution theory and this was evidenced by 19 F NMR analysis.

Some O-fluoro alkyl N,N′-dialkyl isoureas are prepared by reacting fluorinated alcohols RFCH2CH2OH with dicyclohexyl- and diisopropyl-carbodiimides. N,N′-diisopropyl isoureas are checked as alkylation agents for amino acids and amines. They do not work at temperatures lower than 50°C and decompose into urea and fluorinated olefin at higher temperatures. N,N′-diisopropylisoureas hydrochlorides act as efficient surfactants in aqueous solutions.

Ilizarov's method of monofocal compression was used in 30 humeri with a diaphyseal pseudarthrosis. Twenty-one patients had previous surgery but had loosening of the osteosynthesis material. Nine patients initially were treated with a hanging cast, resulting in interfragmentary distraction. Fourteen nonunions were hypertrophic, and 16 were atrophic, of which six were infected. A complete circular frame was used only in the first nine patients, whereas the remaining 21 patients were treated with the modified semicircular fixator. Union was obtained in all but two patients, with an average consolidation time of 4.5 months (range, 2.5-10 months). No patient required additional bone grafting. Apart from superficial pin tract infection seen in most of the patients, three had a minor temporary sensory neurologic problem. Four patients experienced a second fracture after removal of the fixator that required a second application of an Ilizarov frame. Although similar results with regard to union are reported after plate osteosynthesis, there was no radial nerve palsy or deep infection in this series, indicating that the treatment by the Ilizarov technique is associated with less complications. The authors' findings suggest that the Ilizarov method is a reliable treatment for humeral nonunions, even after multiple previous operations or in the event of infection.

The telomerization of C2F4 with C6F13I by various initiators has been achieved. These results have shown the effect of the temperature on the mechanism of the reaction. With t-butylperoxide (DTBP) at 130 degrees C, we have observed that the apparent relative reactivity of C8F17I (monoadduct) is constant versus time. On the contrary, with cyclohexyl percarbonate (CHPC) at 47 degrees C, it decreases continuously. On the other hand the ratio of the initial rates of consumption of monomer to telogen is close to 1 at high temperature while it is near to 2 at low temperature. These results clearly demonstrate that the mechanism proceeds by monoaddition in the first case (DTBP) while it is by propagation in the second case ( CHPC). Secondly, we have proposed a mathematical simulation of these two kinds of reaction and discussed the validity of these laws.

Two sets of hydrophobic porous films were prepared in various conditions of composition and elongation from mixtures of hdPE, silica and diluent. The influence of different parameters on membrane flux, permeability and porosity were studied. Especially, the influences of elongation rate and amount of silica filler were confirmed. On the other hand, the diluent does not appear to be efficient in creating pores. Moreover, the intrinsic properties of the polymer can modify very markedly the properties of the membranes. (C) 1997 Elsevier Science Ltd.

A new method based on the measurement of maximum conversion rate of the least reactive monomer (N-vinylpyrrolidone; NVP) was used to determine the reactivity ratio of glycidyl methacrylate (MAG), that of NVP being considered to be zero. Despite a peculiar experimental difficulty due to the occurrence of NVP homopolymerization, the monomer reactivity ratio of MAG was found to be between 2.87 and 4.05 (at a 95% probability level), in good agreement with data from the literature.

To determine the reactivity ratios in the radical copolymerization of the reaction product of acetylsalicyclic acid with 2,3-epoxypropyl methacrylate and N-vinylpyrrolidone, all available methods are used and compared. Using as criteria the accuracy of the confidence interval and the impossibility of obtaining in any case negative values for a reactivity ratio, the Tidwell-Mortimer method is recommended.

This paper deals with the application of the previously presented model and computer program for predicting 19F NMR chemical shifts to a set of essentially new experimental values recently published in this journal.

This paper presents two programs which allow the ready empirical calculation of fluorine chemical shifts. The first program deals with the management of paramagnetic increment files and the second with the calculation itself.

La calorimétrie différentielle à balayage est appliquée à l'étude de la polymérisation en masse du méthacrylate de méthyle et du méthacrylate de pentafluorophényle (MAPF) en présence de 2,2-azobis(2-méthylpropionitrile) (AIBN) et de peroxydicarbonate de bis(4-tertiobutylcyclohexyle). Les vitesses globales de polymérisation des deux monomères avec l'AIBN sont comparées ainsi que celles du MAPF avec les deux amorceurs. On trouve pour les enthalpies de polymérisation des deux monomères dans le domaine 50–60° des valeurs voisines de 50 kJ · mol−1.