Video: Reactants Used for the Production of Alcohols from Alkenes

When ethanol is made industrially, a catalyst is used to accelerate the combination of ethene with one other reactant. What is the name of that reactant?

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Video Transcript

When ethanol is made industrially, a catalyst is used to accelerate the combination of ethene with one other reactant. What is the name of that reactant?

What we’re looking at is the production of ethanol from ethene. This is the structure of ethene. The “eth” part means that there are two carbon atoms, while the “ene” part means that it is an alkene, meaning that it contains at least one carbon carbon double bond. The question tells us that ethene is combined with one other reactant. Ethene and this reactant combine together to form ethanol.

We can figure out the structure of ethanol by looking at the name. “eth” means two carbon atoms, while “ol” means that it’s an alcohol with an OH group. Now that we have the structures of ethene and ethanol, we can start to deduce the structure of the other reactant. Remember, the question asks for the name of the reactant not the name of the catalyst or any of the reaction conditions.

So let’s have a look at the differences between ethene and ethanol. Ethene has this carbon carbon double bond. Carbon carbon double bonds are well-known to participate in addition reactions, for instance, the bromination of ethene, where bromine inserts into the double bond leaving a bromine on each carbon atom. Something similar might be happening with the reaction of ethene to form ethanol. This H group and the hydroxyl group could have been added by an addition reaction. If that’s so, then if we combine them together, we get a water molecule.

If we insert water as the other reactant, the equation balances. And it makes sense. H₂O is our missing reactant. And the name of the reactant is water. Just in case you’re interested, the catalyst used in this process industrially is phosphoric acid. And the reaction is done at about 300 degrees at 60 to 70 atmospheres of pressure. And the ethene starting material is generally produced by catalytic cracking of crude oil.

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