Question Video: Naming the Product of the Addition Reaction of Ethene and Chlorine Gas | Nagwa Question Video: Naming the Product of the Addition Reaction of Ethene and Chlorine Gas | Nagwa

Question Video: Naming the Product of the Addition Reaction of Ethene and Chlorine Gas Chemistry • Third Year of Secondary School

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What is the name of the product formed during this addition reaction between ethene and chlorine gas?

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Video Transcript

What is the name of the product formed during this addition reaction between ethene and chlorine gas? (A) 1,1-Dichloroethane, (B) chloroethane, (C) chloroethene, (D) 1,1-dichloroethene, or (E) 1,2-dichloroethane.

An addition reaction is a type of chemical reaction where two or more molecules combine to form a larger molecule without any by-products forming. In this addition reaction, ethene is being combined with chlorine gas. As chlorine is a halogen, we can further classify this type of addition reaction as a halogenation reaction, an addition reaction involving the addition of one or more halogens.

The chlorine atoms in this reaction will be added to ethene. Ethene is an alkene, a compound which contains an electron-rich carbon–carbon double bond.

Let’s consider what happens during the halogenation of a generic alkene with a generic diatomic halogen. Over the course of this reaction, the 𝜋 bond between the two carbon atoms will break, as will the bond between the two halogen atoms. This loss of bonds allows for the formation of two new carbon–halogen single bonds. The product of this reaction no longer contains a carbon–carbon double bond, but it does contain two halogen atoms that are attached to adjacent carbon atoms.

With this in mind, let’s take another look at the reaction provided in the question. We know that the 𝜋 bond between the two carbon atoms will break along with the bond between the two chlorine atoms. This will allow for the formation of two new carbon–chlorine single bonds. The product of this reaction no longer contains a carbon–carbon double bond, but it does contain two carbon–chlorine single bonds.

Now that we know the product, we need to determine its name. The longest continuous chain of carbon atoms in this compound is two-carbon-atoms long, so the name will contain the term eth- to indicate that the longest continuous chain is two-carbon-atoms long. The carbon atoms are joined together by a single bond. So we’ll use the suffix -ane to indicate the type of bond between the carbon atoms. There are two chlorine substituents bonded to ethane, so we can add dichloro- to the name. Chloro- is the name of a chlorine substituent, and di- indicates that there are two of these substituents.

Finally, we need to indicate where the chlorine atoms are located in the molecule. One chlorine atom is bonded to carbon number one, and one chlorine atom is bonded to carbon number two. Adding these position numbers to the beginning of the name, we get the name 1,2-dichloroethane. This matches answer choice (E).

Therefore, the name of the product formed during the addition reaction between ethene and chlorine gas is 1,2-dichloroethane, answer choice (E).

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