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Joseph-Achille

Stereochemistry refers to chemistry in three dimensions Its foundations were laid by Jacobus van t Hoff and Joseph Achille Le Bel m 1874 Van t Hoff and Le Bel mde pendently proposed that the four bonds to carbon were directed toward the corners of a tetrahedron One consequence of a tetrahedral arrangement of bonds to carbon is that two compounds may be different because the arrangement of their atoms m space IS different Isomers that have the same constitution but differ m the spatial arrangement of their atoms are called stereoisomers We have already had considerable experience with certain types of stereoisomers—those involving cis and trans substitution patterns m alkenes and m cycloalkanes... [Pg.281]

Joseph Achille Le Bel (IB47-1930I was born in Pechelbronn, France, and studied at the Ecole Polytechnique and the Sorbonne in Paris. Freed by his family s wealth from the need to earn a living, he established his own private laboratory. [Pg.8]

LDA, see Lithium diisopropylamide LDL, heart disease and, 1090-1091 Le Bel, Joseph Achille, 7-8 Leading strand, DNA replication and, 1107... [Pg.1303]

But what about the three-dimensional images or formulations of molecules What about "la chimie en l espace" introduced by Joseph Achille Le Bel, van t Hoff, and Wislicenus toward the end of the nineteenth century Were these carbon tetrahedra realistic "models" of real molecules in space Van t Hoff argued in favor of the carbon tetrahedron that if atoms were arranged in a plane, there would be more isomers of the type CR1R2R3R4 predicted in principle than are actually observed. With the tetrahedral structure, only two isomers are possible, related to each other as mirror images. 102... [Pg.119]

Figure 11. Jacobus Henricus van tHoff (1852-1911) Joseph Achille Le Bel... Figure 11. Jacobus Henricus van tHoff (1852-1911) Joseph Achille Le Bel...
The Fischer projection is a convenient way of showing the configurations of the linear forms of monosaccharides. This convention depicts the concepts of stereochemistry established by Jacobus Henricus van t Hoff and Joseph Achille Le Bel in a simplified form. While these abbreviated structural formulas are simple to write and easy to visualize, there are some guidelines that should be taken into account when converting a three-dimensional structure into a Fischer projection and in its manipulation (Fig. 1.2) ... [Pg.3]

Paper 9 Joseph Achille le Bel, On the Relations Which Exist between the Atomic Formulas of Organic Compounds and the Rotatory Power of Their Solutions. ... [Pg.15]

JOSEPH ACHILLE LE BEL (1847-1930). From Proceedings of the Royal Society of London Series A, Vol. GXXX, 1931. Courtesy of the Royal Society of London. [Pg.162]

From the chirality standpoint the next fundamental development occurred in 1874, when the tetrahedral carbon atom was proposed as a basis for molecular chirality by the Dutch and French chemists Jacobus Henricus van t Hoff (1852— 1911) [47, 48] and Joseph Achille LeBel (1847-1930) [49], respectively, independently and almost simultaneously. The discovery of the asymmetric carbon atom (van t Hoff s terminology) finally provided the explanation for the existence of optical isomers and for the chiral nature of the molecules of optically active substances, including many drugs. In his original 1874 pamphlet proposing the tetrahedron [47] van t Hoff listed camphor as a chiral molecule, but the structure he gave (19) was incorrect. [Pg.16]

Joseph-Achille Le Bel, born in Pechelbronn, France, was, with Dutch physical chemist Jacobus Hendricus van t Hoff, the cofounder of modern stereochemistry. They independently established the relation between optical activity and asymmetric carbon compounds. [Pg.721]


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