Question

Dehydrogenation, dehydrohalogenation

Answer 1

Dehydrogenation: Dehydrogenation refers to the removal of hydrogen atoms from a molecule, resulting in the formation of a double bond. This process is often used to convert saturated hydrocarbons into unsaturated hydrocarbons. The most common example is the dehydrogenation of alkanes to alkenes. For instance, the dehydrogenation of ethane (C2H6) produces ethene (C2H4):

C2H6 → C2H4 + H2 

Dehydrogenation reactions are typically carried out using catalysts, such as platinum or palladium, at high temperatures. These catalysts facilitate the breaking of the C-H bonds and promote the formation of double bonds. Dehydrohalogenation: Dehydrohalogenation involves the elimination of a halogen atom (usually chlorine, bromine, or iodine) and a hydrogen atom from an organic molecule, leading to the formation of a double bond. This process is commonly used to synthesize alkenes or alkynes from alkyl halides. The reaction is often conducted using a strong base, such as potassium hydroxide (KOH) or sodium ethoxide (NaOCH2CH3), which abstracts a proton from the molecule, resulting in the removal of a halogen atom. 

For example, the dehydrohalogenation of 2-chloroethane (C2H5Cl) with potassium hydroxide can yield ethene (C2H4): C2H5Cl + KOH → C2H4 + KCl + H2O 

It's important to note that dehydrohalogenation can also occur in the presence of a strong base without the simultaneous removal of a proton, resulting in the formation of an alkene. 

Both dehydrogenation and dehydrohalogenation reactions are significant in organic chemistry as they provide synthetic pathways to produce unsaturated compounds, which are important in the production of polymers, pharmaceuticals, and various other chemical compounds.