How do you knock off a halogen from a hydrocarbon chain?

[Simfish]

Without introducing any other atoms or double bonds into the chain? (just replace the halogen with a hydrogen atom). Assume for now that the halogen was introduced in the middle of the carbon chain.

 

[Simfish]

Okay I think I solved it.

Dehydrohalogenation removes the halogen and the attached carbon forms a double bond with another carbon. But then hydrogenation of this double bond into a single bond is spontaneous (it just needs a catalyst to speed up).

 

[DDTea]

Pretty much. Yes, it's going to be two separate reactions. Next, you need to reduce the double bond somehow, as by catalytic hydrogenation: i.e., high pressure H2 + a suitable transition metal (Ni, Pd, Pt, Rh, etc).

 

[chemisttree]

That's one way. Another is to treat with Na or K or Li and work up with water. Your way is better for large quantities.

 

[DeeNos]

One way to knock off a halogen from a hydrocarbon chain without introducing any other atoms or double bonds is through a process called dehalogenation. This involves using a reducing agent, such as sodium or lithium, to replace the halogen atom with a hydrogen atom.

The first step in this process is to create a solution of the hydrocarbon chain and the reducing agent. This can be done by dissolving the hydrocarbon in a solvent, such as ether or benzene, and adding the reducing agent to the solution. The reducing agent will then react with the halogen atom, forming a salt and releasing the halogen from the hydrocarbon chain.

Next, the solution is heated to a high temperature, typically around 300-500 degrees Celsius. This high temperature causes the hydrogen atom to bond with the carbon in the hydrocarbon chain, replacing the halogen atom. This reaction can also be catalyzed by a metal, such as palladium or nickel, which helps to speed up the reaction.

After the reaction is complete, the solution is cooled and the resulting product is filtered to remove any remaining reducing agent or byproducts. The final product is a hydrocarbon chain with a hydrogen atom in place of the halogen, and no additional atoms or double bonds have been introduced into the chain.

In summary, dehalogenation is a useful method for removing halogens from hydrocarbon chains without introducing any other atoms or double bonds. This process can be used in various industries, such as in the production of plastics and other organic compounds.