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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The anti conformation is lowest in energy, and the totally eclipsed conformation is highest in energy.
They are named by replacing the -ane ending of the alkane with -yl. Straight chain actually is zigzag. Ambas conformaciones tienen un metil axial y otro ecuatorial. Neopentane, most highly branchedFive possible isomers of hexane,18 isomers of octane and 75 for decane! Conformations of Cyclohexane Caption: Axial hydrogens are pointed straight up or down, parallel to the axis of the ring.
C5H12 C H 3 2 n-pentano iso-pentano neo-pentano Chapter 3. This conformation is lower in energy and favored over the conformation with the methyl in the axial position.
Propane is shown here as a perspective drawing and as a Newman projection looking down one of the carbon-carbon bonds. First in alphabet gets lowest number. Regardless of the other groups present, the most stable conformation has a t-butyl group in an equatorial position.
Wade03 estructura y estereoquimica de alcanos – [PPT Powerpoint]
Chair esterdoquimica would still produce an axial and an equatorial methyl. Viewed from the Newman projection, the chair conformation has no eclipsing of the carbon-carbon bonds. Chapter 3Bicyclic AlkanesFused rings share two adjacent carbons.
Sobre el proyecto SlidePlayer Condiciones de uso. Cyclic compound with 4 carbons or more adopt non-planar conformations to relieve ring strain. Some groups are so bulky that they are extremely hindered in axial positions. Cyclohexanes with tertiary-butyl substituents show that an axial t-butyl group is severely hindered.
The Newman Projection of Propane Caption: Any carbon with four sigma bonds has an sp3 hybridization. All the carbon-carbon bonds are eclipsed, generating torsional strain that contributes to the total ring strain.
The other eclipsed conformations are lower in energy than the totally eclipsed conformation but are still more unstable than the staggered conformations. Newman Projection of Methylcyclohexane: As they are numbered here, the odd-numbered carbons cicloalfanos their upward bonds axial and their downward bonds equatorial.
Often, the longest chain with the most substituents is not obvious. Melting points increase with increasing carbons less for odd- number of carbons. The chair conformation is alcannos stable, followed by the twist boat. Use di- tri- etc. Methane is perfectly tetrahedral, with the This interference is called a 1,3-diaxial interaction.
The C-C bond distance is 1. Compare this actual structure with the hypothetical planar structure in Figure The most stable conformation is the chair because it has all the C-H bonds staggered. All the C-H bonds are staggered in the chair conformation. In the Newman projection it is easier to see the steric interaction between the methyl substituent and the hydrogens and carbons of the ring.
The angle compression of cyclopropane is Solution The longest carbon chain contains eight carbon atoms, so this compound is named as an octane.
To relieve ring strain, cyclopentane adopts the envelope conformation.
Estructura y Estereoquímica de Alcanos
May be cycloalkyl attachment to chain. Chair Conformation estereoquijica Cyclohexane Caption: Three of these conformations are given specific names. Newman Projections of Butane Caption: Comparison of the boiling points of the unbranched alkanes blue with those of some branched alkanes red. The six-membered rings in cis- and trans-decalin assume chair conformations.
Chapter 3Number the CarbonsStart at the end closest to the first attached group.