Download Wade03 estructura y estereoquimica de alcanos . leccin 5. alcanos y cicloalcanos – orgnica 2 leccin 5. Documents. estereoquímica introducción los isómeros estructurales se definen como isómeros, todos aquellos compuestos químicos que poseen igual fórmula global, . Estereoquímica es el término aplicado a los aspectos tridimensionales de la estructura CAPÍTULO TRES Conformaciones de alcanos y cicloalcanos.
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This conformation is lower in energy and favored over the conformation with the methyl in the axial position. When a bond of propane rotates, the torsional dstereoquimica varies much like it does in ethane, but with 0. 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.
Estructura y Estereoquímica de Alcanos
Post on Apr views. The totally eclipsed conformation is about 1. For butane there will be two different staggered conformations: Los botones se encuentran debajo. Angle strain and torsional strain account for the high reactivity of 4-membered rings.
Their physical properties resemble those of alkanes. There are two possible geometric isomers for decalin: Conformations of Cyclopropane Caption: The Newman projection looks straight down the carbon-carbon bond.
Any carbon with four sigma bonds has an sp3 hybridization.
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Methane is perfectly tetrahedral, with the The molecular formula of alkanes is CnH2n, two hydrogen less than an open chain alkane. Conformational Analysis of Ethane Caption: Name the branch off the branch using a locator number. The lowest-energy conformer is most aclanos.
For ethane, only 3. The only intermolecular force of nonpolar molecules are London dispersion forces which result from induced dipole attractions.
Alkyl substituents on cyclohexane rings will tend to be equatorial to avoid 1,3-diaxial interactions. The angle strain and the torsional cicloalcanow in cyclopropane make this ring size extremely reactive.
Chair-chair interconversion of methylcyclohexane.
Wade03 estructura y estereoquimica de alcanos
C5H12 C H 3 2 n-pentano iso-pentano neo-pentano Chapter estereoquimiica. Nomenclature of Alkyl Groups Caption: The angle compression for butane is In this case both chairs have the same energy, and they are present in equal amounts. This puckered conformation reduces the eclipsing of adjacent CH2 groups.
Home Education Wade03 estructura y estereoquimica de alcanos.
Chapter 3End of Chapter 3Chapter estreeoquimica. Some conformations can be more stable than others. Butano tiene 2 conformaciones alternadas diferentes: Chair Conformation of Cyclohexane Caption: The Newman projection is the best way to judge the stability of the different conformations of a molecule.
First in alphabet gets lowest number. Sobre el proyecto SlidePlayer Condiciones de uso. Propane esereoquimica shown here as a perspective drawing and as a Newman projection looking down one of the carbon-carbon bonds. Chair Conformations of trans-1,3-Dimethylcyclohexane Caption: The four hydrogen atoms are covalently bonded to the central carbon atom, with bond lengths of 1. Axial hydrogens are pointed straight up or down, parallel to the axis of the ring.
Looking down the C1-C2 bond of the equatorial conformation, we find that the methyl group is anti to C3. No angle esterwoquimica and no torsional strain. Longer chained alkanes have greater surface area and can have estereoqimica surface contact and more induced dipoles than branched alkanes with smaller surface areas.
Ethane, the two-carbon alkane, is composed of two methyl groups with overlapping sp3 hybrid orbitals forming a sigma bond between them. Use di- tri- etc.
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Ignore di- tri- etc. To convert between these two conformations, the molecule must pass through the unstable half-chair conformation.
Either of the chair conformations of trans-1,3-dimethylcyclohexane has one methyl group in an axial position and one in an equatorial position. Two chair conformations are possible for cis-1,3-dimethylcyclohexane. Angle Strain in Cyclopropane Caption: Angles would beif planar. Cyclobutane adopts the folded conformation to decrease the torsional strain caused by eclipsing hydrogens.
At room temperature, this barrier is easily overcome, and the molecules rotate constantly.
The chair conformation of cyclohexane has one methylene group puckered upward and another puckered downward. Interconversion between chair conformations require that cyclohexane go through its higher energy conformations. Conformations of Cyclobutane Caption: