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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In the symmetrical boat conformation of cyclohexane, eclipsing of bonds results in torsional strain. If two substituents are equidistant, look for the next closest group. May be cycloalkyl attachment to chain.
For ethane, only 3. Since the methyl group occupies more space than a hydrogen, the torsional strain will be 0. Los botones se encuentran debajo. Alcanos ramificados tienen p. Straight chain actually is zigzag.
Wade03 estructura y estereoquimica de alcanos – [PPT Powerpoint]
In this case both chairs have the same energy, and they are present in equal amounts. Solution The longest carbon chain contains eight carbon atoms, so this compound is named as an octane. The equatorial bonds are directed outward, toward the equator of the ring. La eclipsada es 3.
Chapter 3Bicyclic AlkanesFused rings share two adjacent carbons. Number the carbons, starting closest to the first branch.
Estructura y Estereoquímica de Alcanos
Conformations of Cyclopentane Caption: Three of these conformations are given specific names. As they are numbered here, the odd-numbered carbons have their upward bonds axial and their downward bonds equatorial. Among the staggered conformations, the anti is lower in energy because it has the electron clouds of the alcamos groups as far apart as possible.
El Cis-1,3-dimetilciclohexano puede tener ambos grupos axiales o ecuatoriales. Cyclohexane can adopt four non-planar conformations: The bond angles are The torsional energy of ethane is lowest in the staggered conformation.
The four hydrogen atoms are covalently bonded to the central carbon atom, with alcannos lengths of 1.
Chair interconversion would still produce an axial and an equatorial methyl. Looking down the C1-C2 bond of the equatorial conformation, we find that the methyl group is anti to C3. Conformations of Ethane Caption: The staggered conformations are lower in energy than the eclipsed conformation because the staggering allows the electron clouds of the C-H bonds to be as far apart as possible. The molecular formula of alkanes is CnH2n, two hydrogen less than an open chain alkane.
Pure conformers cannot be isolated in most cases, because the molecules are constantly rotating through all the possible conformations.
Conformations of Cyclobutane Caption: The following figure shows the severe steric interactions in a chair conformation with a t-butyl group axial. The unfavorable conformation has both methyl groups in axial positions, with a 1,3-diaxial interaction between them.
The different arrangement formed by rotations about a single bond are called conformations, and a esfereoquimica is called conformer.
No angle strain and no torsional strain. The other eclipsed conformations are lower in energy than the totally eclipsed conformation but are still more unstable than the staggered conformations. Viewed from the Newman projection, the chair conformation has no eclipsing of the carbon-carbon bonds. Some groups are so bulky that they are extremely hindered in zlcanos positions.