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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Parentheses are used around the complex branch name. The totally eclipsed conformation is about 1. La ciclolcanos es 3. The methyl group is axial in one conformation, and equatorial in the other.

Estructura y Estereoquímica de Alcanos – ppt video online descargar

Pure conformers cannot be isolated in most cases, because the molecules are constantly rotating through all the possible conformations. These conformations have equal energies, and they are present in equal amounts. Los botones se encuentran debajo. Longer ccicloalcanos alkanes have greater surface area and can have more surface contact and more induced dipoles than branched alkanes with smaller surface areas.

Alcanos con par de C tienen p. Chair-chair interconversion of methylcyclohexane. Butano tiene 2 conformaciones alternadas diferentes: Los substituyentes axiales interfieren con los H axiales del C 3 y C 5. To relieve ring strain, cyclopentane adopts the envelope conformation.

When molecules can pack in neat order avoiding empty pockets the melting point will be higher than when the packing is not ordered. Methane is perfectly tetrahedral, with the If two substituents are equidistant, look for the next closest group.


The other eclipsed conformations are lower in energy than the totally eclipsed conformation but are still more unstable than the staggered conformations. The angle compression for butane is Melting points increase with increasing carbons less for odd- number of carbons. The following figure shows the severe steric interactions in a chair conformation with a t-butyl group axial.

The bond angles are Much like ethane the staggered conformations of propane is lower in energy than the eclipsed conformations. To use this website, you must agree to our Privacy Policyincluding cookie policy.

Estructura y Estereoquímica de Alcanos

Chapter 3Boiling Points of AlkanesBranched alkanes have less surface area contact,so weaker intermolecular forces. Angle Strain in Cyclopropane Caption: There is steric hindrance between these hydrogens so the molecule twists a little producing the twist boat conformation which is 1.

Conformations of Cyclopropane Caption: The Newman Projection of Propane Caption: All the carbon-carbon bonds are eclipsed, generating torsional strain that contributes to the total ring strain.

Alcohols are compounds whose molecules have a hydroxyl. As they are numbered here, the odd-numbered carbons have their upward bonds axial and their downward bonds equatorial.

When a esfereoquimica of propane rotates, the torsional energy varies much like it does in ethane, but with 0.

In the Newman projection it is easier to see the steric interaction between the methyl substituent and the hydrogens and carbons of the ring. Cyclohexane can adopt four non-planar conformations: Any carbon with four sigma bonds has an sp3 hybridization. The more stable conformation has both methyl groups in equatorial positions. For ethane, only 3.


Looking down the C1-C2 bond of the equatorial conformation, we find that the methyl group is anti cicpoalcanos C3. The different arrangement formed by rotations about a single bond are called conformations, and a specific is called conformer.

Wade03 estructura y estereoquimica de alcanos – [PPT Powerpoint]

An equatorial methyl group will be re to the C3. Structures of some cycloalkanes. Numbering from left to right gives the first branch on C2; numbering from right to left gives the first branch on C3, so we alanos from left to right. El Cis-1,3-dimetilciclohexano puede tener ambos grupos axiales o ecuatoriales. Chair Conformations of cis-1,3-Dimethylcyclohexane Caption: The melting point curve for n-alkanes with even numbers of carbon atoms is slightly higher than that for alkanes with odd numbers of carbons.

The Newman projection looks straight down the carbon-carbon bond. Conformations of Cyclopentane Caption: C5H12 C H 3 2 n-pentano iso-pentano neo-pentano Chapter 3. Ignore di- tri- etc.

Often, the longest chain with the most substituents is not obvious. Since the methyl group occupies more space than a hydrogen, the torsional strain will be 0.