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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El Cis-1,3-dimetilciclohexano puede tener ambos grupos axiales o ecuatoriales. Angle strain in cyclopropane.

conformaciones de butano

Pure conformers cannot be isolated in most lis, because the molecules are constantly rotating through all the possible conformations. This kind of interference between two bulky groups is called steric strain or steric hindrance.

The even-numbered carbons have their downward bonds axial and their upward bonds equatorial. To convert between these two conformations, the molecule must pass through the unstable half-chair conformation.

Newman Projection of Methylcyclohexane: When a bond of propane rotates, the torsional energy varies much like it does in ethane, but with 0. The following figure shows the severe steric interactions in a chair conformation with a t-butyl group axial.



Ambas conformaciones tienen un metil axial y otro ecuatorial. Viewed from the Newman projection, the chair conformation has no eclipsing of the carbon-carbon bonds.

Chair-chair interconversion of methylcyclohexane. Rotations about the center bond in butane give different molecular shapes. Compare this actual structure with the hypothetical planar structure in Figure The six-membered rings in cis- and trans-decalin assume chair conformations.

The axial bonds are directed vertically, parallel to the axis of the ring. Chair Conformations of trans-1,3-Dimethylcyclohexane Caption: There is steric hindrance between these hydrogens so the molecule twists a little producing the twist boat conformation which is 1. To use this website, you must agree to our Privacy Policyincluding cookie policy.

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Los botones se encuentran debajo. Los substituyentes axiales interfieren con los H axiales del C 3 y C 5. Two chair conformations are possible for cis-1,3-dimethylcyclohexane.

The chair conformation is most stable, followed by the twist boat. Comparison of the boiling points of the unbranched alkanes blue with those of some branched alkanes red. In the symmetrical boat conformation of cyclohexane, eclipsing of bonds results in torsional strain. Conformational energy of cyclohexane.

Regardless of the other groups present, the most stable conformation has a t-butyl group in an equatorial position. Conformational Analysis of Ethane Caption: The angle compression of cyclopropane is The high reactivity of cyclopropanes is due to the non-linear overlap lls the sp3 orbitals. Ethane, the two-carbon alkane, is composed of two methyl groups with overlapping sp3 hybrid orbitals forming a sigma bond between them.


When looking for the longest continuous chain, look to find all the different chains of that length.

Angle strain and torsional strain account for the high reactivity of 4-membered rings. The more stable conformation has both methyl groups in equatorial positions. The four hydrogen atoms are covalently bonded confromaciones the central carbon atom, with bond lengths of 1. For butane there will be two different staggered conformations: The Newman projection looks straight down the carbon-carbon bond.

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