ALKENE THEORY
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- Germán Fernández
- ALKENE THEORY
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Alkenes are hydrocarbons that contain carbon-carbon double bonds. The word olefin is frequently used as a synonym.
Alkenes abound in nature. Ethene is a compound that controls plant growth, seed germination and fruit ripening.
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- Germán Fernández
- ALKENE THEORY
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Alkenes are named by replacing the -ane ending of the corresponding alkane with -ene. The simplest alkenes are ethene and propene, also called ethylene and propylene at the industrial level.
![alkenes nomenclature 1](/images/stories/organica-i/alquenos/nomenclatura/nomenclatura-alquenos-1.png)
![alkenes 2 nomenclature](/images/stories/organica-i/alquenos/nomenclatura/nomenclatura-alquenos-2.png)
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- Germán Fernández
- ALKENE THEORY
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Each ring or cycle of a molecule implies the loss of two hydrogens with respect to an alkane of formula CnH2n+2 . The degree of unsaturation is the number of cycles and double bonds present in a molecule.
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- Germán Fernández
- ALKENE THEORY
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The following models show the structure, distances, and bond angles of ethene. Each of the carbons in the molecule is $sp^2$ hybridized. Its geometry is flat, with bond angles close to 120º.
![alkenes-bond-structure alquenos-estructura-enlace](/images/stories/organica-i/alquenos/estructura-enlace/alquenos-estructura-enlace-01.png)
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- Germán Fernández
- ALKENE THEORY
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Alkenes have melting and boiling points close to the corresponding alkanes.
![alkenes-physical-properties alquenos-propiedades-fisicas](/images/stories/organica-i/alquenos/propiedades-fisicas/alquenos-propiedades-fisicas-01.png)
Dipole moment in alkenes. In carbon $sp^2$ the electrons in the s orbital are closer to the nucleus and are strongly attracted to it, so that a carbon $sp^2$ has a tendency to attract electrons towards itself, which generates dipole moments.
![alkenes-physical-properties alquenos-propiedades-fisicas](/images/stories/organica-i/alquenos/propiedades-fisicas/alquenos-propiedades-fisicas-02.png)
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- Germán Fernández
- ALKENE THEORY
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The heats released in the following hydrogenation reactions give us an idea about the different stability of alkenes.
![stability alkenes 01](/images/stories/organica-i/alquenos/estabilidad/estabilidad-alquenos-01.png)
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- Germán Fernández
- ALKENE THEORY
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Alkenes can be prepared from haloalkanes and alkyl sulfonates by bimolecular elimination (E2). In the following example 2-bromo-2-methylbutane reacts with sodium methoxide to form a mixture of 2-methyl-2-butene and 2-methyl-1-butene.
![synthesis-alkenes-e2 sintesis-alquenos-e2](/images/stories/organica-i/alquenos/sintesis-e2/sintesis-alquenos-e2-01.png)
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- Germán Fernández
- ALKENE THEORY
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The treatment of alcohols with mineral acids at high temperatures causes the loss of water, which occurs through E1 or E2 mechanisms.
![dehydration-alcohols-01.png deshidratacion-alcoholes-01.png](/images/stories/organica-i/alquenos/deshidratacion-alcoholes/deshidratacion-alcoholes-01.png)