View alcanos_ from CIENCIAS D at Marista University of Guadalajara. Estructura y conformaciones de los alcanos Conformacin Eclipsada. Estereoqumica de Cicloalcanos disustituidos: ESTABILIDAD DE LOS CICLOALCANOS Adolf. Calores de combustión: Alcano + Oxígeno Geometría molecular, Isomería conformacional, Conformación del ciclohexano, Tensión angular. La isomería ye una propiedá d’aquellos compuestos químicos n’especial les pero’l ciclohexano ye un alcano cíclicu o cicloalcano y el 1-hexeno ye un alqueno. . Los isómeros conformacionales xeneralmente nun son xebrables o.
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All ciclkalcanos carbon-carbon bonds are eclipsed, generating torsional strain that contributes to the total ring strain. These conformations have equal energies, and they are present in equal amounts. Cyclobutane adopts the folded conformation to decrease the torsional strain caused by eclipsing hydrogens. This puckered conformation reduces the eclipsing of adjacent CH2 groups.
Alcanos y Cicloalcanos by Adrian Marcelo Giurno on Prezi
At room temperature, this barrier is easily overcome, and the molecules rotate constantly. When looking for the longest continuous chain, look to find all the different cilcoalcanos of that length. The chair conformation of cyclohexane has one methylene group puckered upward and another puckered downward.
Propane is shown here as a perspective drawing and as a Newman projection looking down one of the carbon-carbon bonds.
Ethane, the two-carbon alkane, is composed of two methyl groups with overlapping sp3 hybrid orbitals forming a sigma alcaos between them. The conformation of cyclobutane is slightly folded.
Chair Conformations of cis-1,3-Dimethylcyclohexane Caption: In the symmetrical boat conformation of cyclohexane, eclipsing of bonds results in torsional strain. Interconversion between chair conformations require that cyclohexane go through its higher energy conformations. C5H12 C H 3 2 n-pentano iso-pentano neo-pentano Chapter 3. Two chair conformations are possible for cis-1,3-dimethylcyclohexane.
In this case both chairs have the same energy, and they are present in equal amounts. Alkanes dde an even cicloalcanow of carbons pack better than those with an odd number of carbons.
Estructura y Estereoquímica de Alcanos
Viewed from the Newman projection, the chair conformation has no eclipsing of the carbon-carbon bonds. Alcohols are compounds whose molecules have a hydroxyl. Three of these conformations are given specific names.
Ethane has two sp3 carbons.
In the actual molecule, the boat conformation is skewed to give the twist boat, a conformation with less eclipsing of bonds and less interference between the two flagpole hydrogens. Some common alkyl groups and their names. Angle Strain in Cyclopropane Caption: The most stable conformation is the chair because it has all the C-H bonds staggered.
Cyclohexane can adopt four non-planar conformations: Conformational Analysis of Propane Caption: Because of their smaller surface areas, branched alkanes have lower boiling points than unbranched alkanes. The anti conformation is lowest in energy, and the totally eclipsed conformation is highest in energy.
Butano tiene 2 conformaciones alternadas diferentes: Conformations with Extremely Bulky Groups Caption: Some conformations can be ciclialcanos stable than others. Cyclic compound with 4 carbons or more adopt non-planar conformations to relieve ring strain.
The Newman projection is the best way to judge the stability isomerka the different conformations of a molecule. The ring strain of a planar cyclobutane results from two factors: Chair interconversion would still produce an axial and an equatorial methyl. Chair Conformation of Cyclohexane Caption: The other eclipsed conformations are lower in energy than the totally eclipsed conformation but are still more unstable than the staggered conformations. The conformation of cyclopentane is slightly folded, like the shape of an envelope.
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Boat Conformation of Cyclohexane Caption: The methyl group is axial in one conformation, and equatorial in the other. Chair-chair interconversion of methylcyclohexane.
The eclipsed conformations are higher in energy than the staggered conformations of butane, especially the totally eclipsed conformation.
In solids, the packing alcanis the molecules into a three dimensional structure affects the melting point. The following figure shows the severe steric interactions in a chair conformation with a t-butyl group axial. When molecules can pack in neat order avoiding empty pockets the melting point will be higher than when the packing is not ordered.
Angle strain and torsional strain account for the high reactivity of 4-membered rings.