Alkenes from alkanes through elimination from "summary" of Organic Chemistry by William H. Brown,Brent L. Iverson,Eric Anslyn,Christopher S. Foote
Alkenes can be formed from alkanes by using a process known as elimination. This involves the removal of two hydrogen atoms from the alkane, resulting in a double bond and an alkene. By doing so, the reactant is converted to a product with fewer hydrogen atoms.- These elimination reactions involve breaking the single bond between two adjacent atom to make an alkene molecule. This reaction requires applying heat or ultraviolet light energy in order for it to occur.
- Alkenes are organic compounds composed of two carbon atoms linked with a double bond. They can be created from alkanes, which have single bonds between their carbon atoms, through elimination reactions.
- Another type of alkene formation is called dehydrohalogenation where the hydrogen atom is removed along with one halogen atom via heating. It usually happens when R-Br is treated with KOH in alcohol as solvent.
- On the other hand, another way to obtain alkenes from alkanes is known as the dehydration of alcohols. This process involves removing water molecules from the alcohol. A common example is E2 elimination of ethanol.
- The best starting materials for these types of elimination reactions are often primary and secondary halogenoalkanes because they contain polarization at the C-X (X being the halogen. so the electron density is greater around the halogen atom making it easier to break the bond.
- With a -elimination reaction, removing the hydroxyl group leaves behind a carbocation which is then attacked by a nucleophile. Depending on what product we want, the reaction conditions will be adjusted accordingly.
- Dehydrogenation is different than the other methods in that it involves removing hydrogen atoms rather than halogens or alcohol components. It usually occurs when unsaturated hydrocarbons are exposed to metals such as palladium or aluminum at high temperatures.
