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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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Regardless of the other groups present, the most stable conformation has a t-butyl group in an equatorial position. The following figure shows the severe steric interactions in confomraciones chair conformation with a t-butyl group axial.

Chair Conformations of trans-1,3-Dimethylcyclohexane Caption: Alcanos ramificados tienen p. The six-membered rings in cis- and trans-decalin assume chair conformations.

All conformacionnes carbon-carbon bonds are eclipsed, generating torsional strain that contributes to the total ring strain. C5H12 C H 3 2 n-pentano iso-pentano neo-pentano Chapter 3. 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.


Análisis conformacional by Química Orgánica on Prezi

The more stable conformation has both methyl groups in equatorial positions. When looking for the longest continuous chain, look to find all the different chains of that length. Conformational Analysis of Ethane Caption: Los loa se encuentran debajo.

Chair Conformations of cis-1,3-Dimethylcyclohexane Caption: The eclipsed aalcanos is about 3. Los substituyentes axiales interfieren con los H axiales del C 3 y C 5. Some common alkyl groups and their names.

The high reactivity of cyclopropanes is due to the non-linear overlap of the sp3 orbitals. All the C-H bonds are staggered in the chair conformation. Alkanes with an even number of carbons pack better than those with an odd number of carbons. The torsional energy of ethane is lowest in the staggered conformation.

El Cis-1,3-dimetilciclohexano puede tener ambos grupos axiales o ecuatoriales. Folding gives partial relief from the eclipsing of bonds, as shown in the Newman projection. Torsional energy of butane.

Khan Academy on a Stick : conformaciones de butano

The C-C bond distance is 1. 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.

Often, the longest chain with the most substituents is not obvious.


This puckered conformation reduces the eclipsing of adjacent CH2 groups. Newman Projection of Methylcyclohexane: Angle strain in cyclopropane. Conformational Analysis of Butane Caption: Boat Conformation of Cyclohexane Caption: In the symmetrical boat conformation of cyclohexane, eclipsing of bonds results in torsional strain.

Estructura y Estereoquímica de Alcanos

The Newman Projection of Propane Caption: Methane alcanoa perfectly tetrahedral, with the Torsional strain in cyclopropane. Conformational Energy Diagram of Cyclohexane Caption: Conformations of Ethane Caption: La eclipsada es 3.

These conformations have equal energies, and they are present in equal amounts. Either of the chair conformations of trans-1,3-dimethylcyclohexane has one methyl group in an axial position and one in an equatorial position.

Melting Points of Alkanes Caption: The angle strain and the torsional strain in cyclopropane make this ring size extremely reactive.

To convert between these two conformations, the molecule must pass through the unstable half-chair conformation.