Alkenes and Hydrogen?

Question

What happens if you add H2 to an alkene? Would the bonds break and would it result in an alkane? An example would be helpful. Also, is it possible to add H2 to benzene?

Answer 1

When you add H2 to an alkene, it does result to an alkane. It can be done using Palladium (Pd), or Platinum (Pt) as a catalyst for the reaction.

If you want, however, to be stereospecific on the type of alkane you produce, say a CIS, or a TRANS, special types of catalyst should be used.

If you want a Cis-oriented molecule, use H2 and a LINDLAR catalyst.

If you want to reduce an alkene to a Trans-oriented alkane, you need not use H2, you could just use Na or Li in NH3(liquid). Lithium, I think, would be much better to use, since it would not react violently because of the presence of the liquid in NH3.

With regards to benzene, H2 can be used, but it's a very SLOW reaction. I suggest using Rhodium (Rh) as a catalyst. Hence, it will remove all the double bonds in the benzene ring, completely converting it to a cyclohexane.

Hope that helped! =)

Answer 2

When you add H2 to an alkene, the double bond breaks and two new C-H bonds are formed. It is called a reduction reaction.

H2 can also be added to Benzene.

Answer 3

The direct answer on your question as this is worded is : No you will no longer. yet, alkenes will conveniently react with hydrogen decrease than stress in the presence of a catalyst to variety the alkane. Finely divided platinum and pallaium are fective at room temperature. Nickel calls for temperature between 200 and 3 hundred°C. C2H4 + H2 (catalyst/stress) ? C2H6