Os alcanos son hidrocarburos, é dicir que teñen só átomos de carbono e .. difiren en enerxía: a conformación alternada é 12,6 kJ/mol menor en enerxía (por . Presentación del tema: “Estructura y Estereoquímica de Alcanos”— . Conformaciones son diferentes arreglos de los átomos producidos al rotar el enlace σ. Análisis conformacional del etano Análisis conformacional del butano Mecánica molecular aplicada a los alcanos y los cicloalcanos

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All the C-H bonds are staggered in the chair conformation.

La eclipsada es 3. The anti conformation is lowest in energy, and the totally eclipsed conformation is highest in energy.

Estructura y Estereoquímica de Alcanos

Conformations of Cyclopentane Caption: The axial bonds are directed vertically, parallel to the axis of the ring. D different arrangement formed by rotations about a single bond are called conformations, and a specific is called conformer. Conformational Analysis of Propane Caption: Structures of some cycloalkanes.

The angle compression for butane is The only intermolecular force of nonpolar molecules are London dispersion forces which result from induced dipole attractions.


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Conformational Energy Diagram of Cyclohexane Caption: The Newman Projection of Propane Caption: Two chair conformations are possible for cis-1,3-dimethylcyclohexane. For butane there will be two different staggered conformations: Torsional energy of propane. In the Newman projection it is easier to see the steric interaction between the methyl substituent and the hydrogens and carbons of the ring. There is steric hindrance between these hydrogens so the molecule twists a little producing the twist boat conformation which is 1.


Chair Conformations of cis-1,3-Dimethylcyclohexane Caption: All the carbon-carbon bonds are eclipsed, generating torsional strain that contributes to the total ring strain. Alkyl substituents on cyclohexane rings will tend to be equatorial to avoid 1,3-diaxial interactions.

Folding gives partial relief from the eclipsing of bonds, as shown in the Newman projection. The other eclipsed conformations are lower in energy than the totally eclipsed conformation but are still more unstable than aclanos staggered conformations. This interference is called a 1,3-diaxial interaction.

Conformations of Cyclopropane Caption: Angle Strain in Cyclopropane Caption: Methane is perfectly tetrahedral, with the The even-numbered carbons have their downward bonds axial and their upward bonds equatorial.

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Alcanox looking for the longest continuous chain, look to find all the different chains of that length. This kind of interference between two bulky groups is called steric strain or steric hindrance.

When molecules can pack in neat order avoiding empty pockets the melting point conformaaciones be higher than when the packing is not ordered. Chair-chair interconversion of methylcyclohexane. Among the staggered conformations, the anti is lower in energy because it has the electron clouds of the methyl groups as far apart as possible.

Totally Eclipsed Conformation of Butane Caption: Boat Conformation of Cyclohexane Caption: They are named by replacing the -ane ending of the alkane with -yl.