Download or read book ETUDE PAR RMN DE LA CONFORMATION DES EXTRACTANTS A FONCTION AMIDE EN PHASE ORGANIQUE written by Claude Berthon and published by . This book was released on 1993 with total page 209 pages. Available in PDF, EPUB and Kindle. Book excerpt: CETTE ETUDE SE SITUE DANS LE CADRE DU RETRAITEMENT DES DECHETS RADIOACTIFS ET A ESSENTIELLEMENT FAIT APPEL A LA RMN. NOUS NOUS SOMMES INTERESSES AUX FACTEURS CONFORMATIONNELS AFIN DE COMPRENDRE LES PHENOMENES QUI CONTROLENT LA SELECTIVITE ET L'EFFICACITE DES EXTRACTANTS A FONCTION AMIDE. LES MONOAMIDES SYMETRIQUES SELECTIONNES DOBA (C#3H#7CON(CH#2CH(C#2H#5)C#4H#9)#2), DOIBA ((CH#3)#2CCHON(CH#2CH(C#2H#5)C#4H#9)#2) ET DOTA ((CH#3)#3CCH#2CON(CH#2CH(C#2H#5)C#4H#9)#2) EXISTENT EN PHASE ORGANIQUE SOUS FORME DE DEUX CONFORMERES QUASI EQUIVALENTS CIS ET TRANS. LE MALONAMIDE SELECTIONNE DMDBTDMA ((C#4H#9(CH#3)NCO)#2CHC#1#4H#2#9) PRESENTE QUATRE CONFORMERES EN RAISON DE LA DISSYMETRIE DE SES DEUX FONCTIONS AMIDES. DES INTERACTIONS FAIBLES ENTRE MOLECULES ET MONOAMIDES PERMETTENT LEUR ASSOCIATION SOUS FORME DE DIMERES. LE MALONAMIDE DONNE NON SEULEMENT DES DIMERES MAIS AUSSI DES AGREGATS. LA MODELISATION DE L'EXTRACTION DE L'ACIDE NITRIQUE A PERMIS DE DECRIRE LE SYSTEME EN PRENANT EN COMPTE SIX ESPECES CHIMIQUES: L,L#2,L#2(HNO#3),L(HNO#3),L(HNO#3)#2,L(HNO#3)#3 (L ETANT UN MONOAMIDE). LES LANTHANIDES (LN: LANTHANIDE) TRIVALENTS SONT COMPLEXES PAR LES MONOAMIDES SOUS LA FORME DE COMPLEXES NEUTRES L#3LN(NO#3)#3 ET L#2LN(NO#3)#3. LEUR PROPORTION DEPEND DE L'ENCOMBREMENT STERIQUE SUR LE CARBONYLE ET DU RAYON IONIQUE DU METAL. CECI EST AUSSI OBSERVE POUR L'EXTRACTION EN MILIEU FAIBLEMENT ACIDE DE PU#4#+ ET TH#4#+ PAR LES MONOAMIDES. LE COMPLEXE MAJORITAIRE EST: L#2AN(NO#3)#4 (AN: ACTINIDE) SAUF POUR LE SYSTEME TH#4#+-DOBA OU APPARAIT L'ESPECE SUPPLEMENTAIRE (DOBA)#3TH(NO#3)#4. DES CINETIQUES D'ECHANGE ENTRE LA MOLECULE D'EXTRACTANT ET LE COMPLEXE SONT OBSERVES. DES DIFFERENCES CONFORMATIONNELLES CARACTERISTIQUES DES COMPLEXES DE LANTHANIDES ET D'ACTINIDES PERMETTENT D'EXPLIQUER POURQUOI LES AN#4#+ SONT EXTRAITS ET PAS LES LN#3#+

Download or read book Government Reports Announcements Index written by and published by . This book was released on 1995 with total page 560 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Analyse et nouvelle approche pr dictive du ph nom ne de formation d une troisi me phase dans les syst mes d extraction akylmalonamide hydrocarbure acide eau written by Lydie Lefrançois and published by . This book was released on 1999 with total page 191 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dans le cadre du retraitement du combustible nucléaire usé, le procédé d'extraction liquide-liquide DIAMEX, envisagé pour la séparation des actinides III, utilise comme extractant le diméthyldibutyltétradécylmalonamide, noté DMDBTDMA. Le problème majeur intervenant dans ce procédé est l'apparition d'une troisième phase dans certaines conditions d'acidité de la phase aqueuse à traiter. L'objectif de ce travail a été d'étudier ce phénomène, du point de vue physico-chimique et de développer un modèle permettant de prévoir la démixtion. Des analyses ont permis de préciser par des techniques appropriées la composition des phases organiques avant et après démixtion. Elles indiquent qu'aux fortes acidités, la troisième phase contient la quasitotalité de l'extractant, de l'eau et de l'acide extraits tandis que la phase sumageante est très riche en solvant. L'étude stéréochimique du diamide par RMN a montré que la conformation Z est toujours majoritaire et le devient encore plus en troisième phase. Les barrières de rotation de la fonction amide ont été précisées. La molécule de DMDBTDMA s'organise sous forme d'agrégats inverses qui s'associent juste avant la démixtion comme l'indique les cassures observées dans les courbes de tension interfaciale. Des essais ont été faits pour tenter de caractériser la polarité des agrégats qui de toute évidence joue un rôle dans ce processus d'agrégation. Un modèle théorique a été développé à partir de la théorie de Flory-Huggins et des paramètres de solubilité. Cette approche conduit au calcul de X12, un paramètre d'interaction solvant/agrégat. La corrélation de X12 avec l'acidité permet d'attribuer à l'extractant un paramètre de solubilité dépendant de son état de protonation. Le modèle prédit correctement la courbe de démixtion et l'effet sur celle-ci de divers paramètres (acidité, nature du solvant, température, nature des anions en solution), tout en prenant en compte le nombre d'agrégation du DMDBTDMA, évalué entre 5 et 10.

Download or read book Transportation and the Future written by United States. Department of Transportation. Assistant Secretary for Governmental Affairs and published by . This book was released on 1979 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Modern Tools for the Synthesis of Complex Bioactive Molecules written by Janine Cossy and published by John Wiley & Sons. This book was released on 2012-10-09 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: All the latest tools needed to plan and perform the synthesis of complex bioactive molecules Focusing on organic, organometallic, and bio-oriented processes, this book explores the impact and use of the latest synthetic tools for the synthesis of complex biologically active compounds. Readers will discover step by step how these synthetic tools have provided new, elegant solutions to many synthetic puzzles. Moreover, they will discover innovative methods that make it possible to control the exact connectivity of atoms within a molecule in order to set precise three-dimensional arrangements. Modern Tools for the Synthesis of Complex Bioactive Molecules features sixteen chapters, each one written by one or more leading experts in organic synthesis from around the world. It covers a broad range of topics that enable readers to take advantage of the latest methods for synthesizing complex molecules, including: Modern catalysis, emphasizing key transformations such as C-H functionalizations, cross-couplings, gold-catalyzed reactions, metathesis-based syntheses, and asymmetric organocatalysis Eco-compatible transformations, including rearrangements and domino reactions Tools for the synthesis of carbohydrates and alkaloids New techniques, including the use of fluorous tags and engineered biosynthesis The last two chapters explore target- and diversity-oriented organic synthesis as well as the use of DNA-based asymmetric catalysis, which are all promising tools for the successful synthesis of complex bioactive molecules. Modern Tools for the Synthesis of Complex Bioactive Molecules is ideal for students and researchers who need to plan and perform the synthesis of complex molecules as efficiently as possible. The book's expert advice will help these readers quickly resolve a broad range of problems that can arise in organic syntheses.

Download or read book Reactions and Syntheses written by Lutz F. Tietze and published by John Wiley & Sons. This book was released on 2015-06-22 with total page 667 pages. Available in PDF, EPUB and Kindle. Book excerpt: The second edition of this classic text book has been completely revised, updated, and extended to include chapters on biomimetic amination reactions, Wacker oxidation, and useful domino reactions. The first-class author team with long-standing experience in practical courses on organic chemistry covers a multitude of preparative procedures of reaction types and compound classes indispensable in modern organic synthesis. Throughout, the experiments are accompanied by the theoretical and mechanistic fundamentals, while the clearly structured sub-chapters provide concise background information, retrosynthetic analysis, information on isolation and purification, analytical data as well as current literature citations. Finally, in each case the synthesis is labeled with one of three levels of difficulty. An indispensable manual for students and lecturers in chemistry, organic chemists, as well as lab technicians and chemists in the pharmaceutical and agrochemical industries.

Download or read book Masters Theses in the Pure and Applied Sciences written by Wade H. Shafer and published by Springer. This book was released on 1976 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt: Masters Theses in the Pure and Applied Sciences was first conceived, published, and dis· seminated by the Center for Information and Numerical Data Analysis and Synthesis (CINDAS) *at Purdue University in 1957, starting its coverage of theses with the academic year 1955. Beginning with Volume 13, the printing and dissemination phases of the ac· tivity were transferred to University Microfilms/Xerox of Ann Arbor, Michigan, with the thought that such an arrangement would be more beneficial to the academic and general scientific and technical community. After five years of this joint undertaking we had concluded that it was in the interest of all concerned if the printing and distribution of the volume were handled by an international publishing house to assure improved service and broader dissemination. Hence, starting with Volume 18, Masters Theses in the Pure and Applied Sciences has been disseminated on a worldwide basis by Plenum Publishing Corporation of New York, and in the same year the coverage was broadened to include Canadian universities. All back issues can also be ordered from Plenum. We have reported in Volume 20 (thesis year 1975) a total of 10,374 theses titles from 28 Canadian and 239 United States universities. We are sure that this broader base for theses titles reported will greatly enhance the value of this important annual reference work. The organization of Volume 20 is identical to that of past years. It consists of theses titles arranged by discipline and by university within each discipline.

Download or read book Bioactive Heterocycles written by and published by . This book was released on with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effects of Early Experience written by Marshall R. Jones and published by . This book was released on 1970 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt: