catalytic (de)hydration/cracking

Question

1catalytic hydration係咪即係以水作為catalyst 的reaction?
例如:
ethene+H2O=ethanol
這是catalytic hydration?

2 catalytic dehydration 係咪即係catalytic hydration的 opposite?
例如:
ethanol=ethene+H2O
這是catalytic dehydration?

3
呢個reaction:ethanol=ethene+H2O
係咪reversible?

4
係咪無論有OH group 果d(如ethanol,but-1-ol)果d 羅去做cracking
就得到 alkene group?
咁catalytic hydration 係咪即係許cracking 發生?

5
咁我倒轉羅alkene 做cracking 係咪就得唔到 alkanol group?

THX

Answer 1

First of all, I suggest you should understand the definitions of different terms.

Catalytic Hydration is a reaction that adds H2O in hydrocarbon in presence of catalyst.

Catatytic Dehydration is a reaction that removes H2O in hydrocarbon in presence of catalyst.

Cracking a break down process of large hydrocarbon molecules.

1) CH2=CH2 + H20 -> CH3CH2OH under conc. H2SO4

Acid act as catalyst in this reaction, not water.

2) Theoretically, yes, but not all catalystic reaction can be reversible.

3) Yes

4) No. Cracking breaks down large hydrocarbon. If you run cracking on long chain alcohols, it may produce alkene. However, as short as ethanol. No cracking should be occurred.

5) Never. Cracking of alkene only give you smaller hydrocarbons, but never creating alcohols.