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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Any carbon with four sigma bonds has an sp3 hybridization. Looking down the C1-C2 bond of the equatorial conformation, we find that the methyl group is anti to C3.

Estructura y Estereoquímica de Alcanos

The different arrangement formed by rotations about a single bond are called conformations, and a specific is called conformer. The chair conformation of cyclohexane has one methylene group puckered upward and another puckered downward.

For butane there will be two different staggered conformations: This kind of interference between two bulky groups is called steric strain or steric hindrance. The angle compression for butane is Newman Projection of Methylcyclohexane: 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. The angle strain and the torsional strain in cyclopropane make this ring size extremely reactive. At room temperature, this barrier is easily overcome, and the molecules rotate constantly.


Either of the chair conformations of trans-1,3-dimethylcyclohexane has one methyl group in an axial position and one in an equatorial position. Ethane, the two-carbon alkane, is composed of two methyl groups with overlapping sp3 hybrid orbitals forming a sigma bond between them. Conformations of Cyclopentane Caption: Groups like tert-butyl are so bulky that it ee force the chair conformation where it is in the equatorial position, regardless of other groups present.

Same Length Chains Caption: In solids, the packing of the molecules into a three dimensional structure affects the melting point. Because cicloakcanos their smaller surface areas, branched alkanes have lower boiling points than unbranched alkanes.

Isomería – Wikipedia

They are named by replacing the -ane ending of the alkane with -yl. When molecules can pack in neat order avoiding empty pockets the melting point will be higher than when the packing is not ordered. Nomenclature of Alkyl Groups Caption: Conformations with Extremely Bulky Groups Caption: 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 chair conformation is most stable, followed by the twist boat. Conformations of Cyclohexane Caption: Isomerix bond angles are In the symmetrical boat conformation of cyclohexane, eclipsing of bonds results in torsional strain. Cyclobutane adopts the folded conformation to decrease the torsional strain caused by eclipsing hydrogens.

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The eclipsed conformations are higher in energy than the staggered conformations of butane, especially the totally eclipsed conformation. The totally eclipsed conformation is about 1.


There are two possible geometric isomers for decalin: Three of these conformations are given specific names. Torsional energy of propane.

This puckered conformation reduces the eclipsing of adjacent CH2 groups. Substituents on a carbon chain are called alkyl groups. Cyclohexane can adopt four non-planar conformations: Their physical properties resemble those of cnformacional. Totally Eclipsed Conformation of Butane Caption: The axial bonds are directed vertically, parallel to the axis of the ring.

Chair interconversion would still produce an axial and an equatorial methyl. The equatorial bonds are directed outward, toward the equator of the ring.

Much like ethane the staggered conformations of propane is lower in energy than the eclipsed conformations. Some conformations can be more stable than others.

Numbering from left to right gives the first branch on C2; numbering from right to left gives the first branch on C3, so we number from left to right. When looking for the longest continuous chain, look to find all the different chains of that length.

Alkyl substituents on cyclohexane rings will tend to be equatorial to avoid 1,3-diaxial interactions. The conformation of cyclobutane is slightly folded. The ring strain of a planar cyclobutane results from two factors: Alcanos ramificados tienen p.