Critical Perspective: Named Reactions Discovered and Developed by Women

Named organic reactions. As chemists, we’re all familiar with them: who can forget the Diels−Alder reaction? But how much do we know about the people behind the names? For example, can you identify a reaction named for a woman? How about a reaction discovered or developed by a woman but named for her male adviser? Our attempts to answer these simple questions started us on the journey that led to this Account. We introduce you to four reactions named for women and nine reactions discovered or developed by women. Using information obtained from the literature and, whenever possible, through interviews with the chemists themselves, their associates, and their advisers, we paint a more detailed picture of these remarkable women and their outstanding accomplishments. Some of the women you meet in this Account include Irma Goldberg, the only woman unambiguously recognized with her own named reaction. Gertrude Maud Robinson, the wife of Robert Robinson, who collaborated with him on several projects including the Piloty−Robinson pyrrole synthesis. Elizabeth Hardy, the Bryn Mawr graduate student who discovered the Cope rearrangement. Dorothee Felix, a critical member of Albert Eschenmoser’s research lab for over forty years who helped develop both the Eschenmoser−Claisen rearrangement and the Eschenmoser−Tanabe fragmentation. Jennifer Loebach, the University of Illinois undergraduate who was part of the team in Eric Jacobsen’s lab that discovered the Jacobsen−Katsuki epoxidation. Keiko Noda, a graduate student in Tsutomu Katsuki’s lab who also played a key role in the development of the Jacobsen−Katsuki epoxidation. Lydia McKinstry, a postdoc in Andrew Myers’s lab who helped develop the Myers asymmetric alkylation. Rosa Lockwood, a graduate student at Boston College whose sole publication is the discovery of the Nicholas reaction. Kaori Ando, a successful professor in Japan who helped develop the Roush asymmetric alkylation as a postdoc at MIT. Bianka Tchoubar, a critically important member of the organic chemistry community in France who developed the Tiffeneau−Demjanov rearrangement. The accomplishments of the women in this Account illustrate the key roles women have played in the discovery and development of reactions used daily by organic chemists around the world. These pioneering chemists represent the vanguard of women in the field, and we are confident that many more of the growing number of current and future female organic chemists will be recognized with their own named reactions

Disordered porous solids : from chord distributions to small angle scattering

Disordered biphasic porous solids are examples of complex interfacial media. Small angle scattering strongly depends on the geometrical properties of the internal surface partitioning a porous system. Properties of the second derivative of the bulk autocorrelation function quantitatively defines the level of connection between the small angle scattering and the statistical properties of this interface. A tractable expression of this second derivative, involving the pore and the mass chord distribution functions, was proposed by Mering and Tchoubar (MT). Based on the present possibility to make a quantitative connection between imaging techniques and the small angle scattering, this paper tries to complete and to extend the MT approach. We first discuss how chord distribution functions can be used as fingerprints of the structural disorder. An explicit relation between the small angle scattering and these chord distributions is then proposed. In a third part, the application to different types of disorder is critically discussed and predictions are compared to available experimental data. Using image processing, we will consider three types of disorder : the long-range Debye randomness, the “ correlated " disorder with a special emphasis on the structure of a porous glass (the vycor), and, finally, complex structures where length scale invariance properties can be observed.Les solides poreux biphasiques sont des exemples de milieux interfaciaux complexes. La diffusion aux petits angles (SAS) dépend fortement des propriétés géométriques de l'interface partitionant le milieu poreux. Les propriétés de la dérivée seconde de la fonction d'autocorrélation de densité définit quantitativement le niveau de connection entre la diffusion aux petits angles et les caractéristiques statistiques de cette interface. Une expression utilisable de cette seconde dérivée, impliquant les distributions de cordes associées à la phase massique et au réseau de pores, fut proposée par Mering et Tchoubar (MT). Mettant à profit la possibilité actuelle d'une comparaison quantitative entre les techniques d'imagerie et la diffusion aux petits angles, ce papier tente de compléter et d'étendre l'approche MT. Dans un premier temps, nous montrons en quoi la connaissance de ces distributions de cordes permet de distinguer certains types de désordres structuraux. Une relation explicite entre le spectre de diffusion aux petits angles et les distributions de cordes est alors proposée. Dans une troisième partie, l'application à différents types de désordre est discutée et les prédictions du modèle comparées aux résultats expérimentaux disponibles. Par utilisation du traitement d'images, nous nous intéressons à trois types de désordre : le milieu aléatoire de Debye, pour ses propriétés à grandes distances, le désordre “ corrélé " avec une attention particulière pour le cas d'un verre poreux (le Vycor) et enfin des organisations complexes où des propriétés d'invariance d'échelle de longueur peuvent être observées

CdSxSe1-x nanocrystals in a silicate glass

A dilute system of CdSxSe1-x nanocrystals with low anisotropy and low size dispersion has been studied by SAXS. The presence of angularities at the surface of the nanoparticles is evidenced from the limit at zero of the chord distribution function. Moreover in a model of spherical particles the size given by the average chord does not agree with that given by the integral parameters. A cubic particle shape has been used to evaluation of the size distribution. This distribution agrees with the expected one, and allows to confirm the validity of a polyedral model for the treatment of the SAXS data. Structural information on the particle surface can be deduced from the presence of the angularities

X-ray scattering functions of fractal structures : comparison between simulations and experiments

Small angle X-ray scattering (S.A.X.S.) functions of aluminum hydroxide aggregates Al (OH)x, are quantitatively compared with the ones obtained from numerical simulations on cluster-cluster (C1-C1) aggregation models. While the x = 2.6 case is fitted by the standard 3d model, the x = 2.5 case can be fitted by a newly developed « tip-to-tip » 3d model, which considers cluster polarizability.Les spectres de diffusion aux petits angles produits par deux solutions d'hydroxyde d'aluminium Al (OH)x (avec x = 2,5 et x = 2,6 ) sont comparées quantitativement à ceux déduits à partir de simulations numériques relatives aux modèles d'agrégation par collage d'amas (C1 - C1). Nous montrons que si l'échantillon x = 2,6 est bien représenté par le modèle standard C1-Cl 3d, par contre les agrégats formés à x = 2,5 correspondent à un modèle 3d récemment développé, dit « par collage de pointes » qui fait intervenir la polarisabilité des amas

X-ray scattering functions of fractal structures : comparison between simulations and experiments

11 ref.International audienc

Structural characterization of Aluminium hydroxide aggregates by S.A.X.S. : Comparison between simulations of fractal structures and experiments

International audienc

Small-angle- X-ray scattering investigations of silica/water inteface : evolution of the structure with pH

27 ref.International audienc

Détermination par D.P.A.X. de la structure fractale d'agrégats obtenus par collage d'amas. Etude de deux solutions d'hydroxyde d'aluminium Al(OH)x avec x = 2,5 et 3

We have studied the structure and the power-law correlation of two typical aluminium hydroxide colloidal aggregates, Al(OH)2.5 and Al(OH) 3, by small angle X-ray scattering. The reliability of this method according to the X-ray scattering scale is discussed.Détermination, par diffusion aux petits angles des rayons X, de la structure et de la fractalité des agrégats colloïdaux présents dans les gels d'hydroxyde d'aluminium Al(OH)2,5 et Al(OH)3