2,2,3,3-Tetrabromopentane can be prepared by an addition reaction of excess Br 2 with an alkyne. Draw the structure of the alkyne and name it.

All right. Hi, everyone. So this question says, if an addition reaction involving excess co two with an all kind produces 3344 tetra Chloro Hexane provide the all kind structure and its name. So the first thing I want to do here is go ahead and actually draw our product, right? Our 3344 tetra chloral exane, our product in this case is a six carbon parent chain with a total of four chlorine atoms attached to it, right? So two of them are on carbon three of the perry chain and the other two are on carbon four of the parent chain. So now this he lied was the product of a reaction involving elemental chlorine or cl two in excess as well as an all kind. Now recall that all kinds are hydrocarbon molecules with carbon, carbon tural bonds. So before we get into the specific reaction that we're dealing with here, I want to point a few things out because sometimes an all kind reaction can be familiar to or similar to allen reactions. So first, let me discuss a similar reaction involving all keen, specifically, we can talk about the halogen generation of an old king. So if I take my all keen here with a carbon carbon double bond, and I react this with, well, not specifically chlorine, right, any halogen. So X two, then what happens here is that each halogen atom attaches itself to each carbon of the double bond. So I end up with a molecule that has two halogen atoms on adjacent carbon. So the reason why I'm bringing this up now is because with all kinds, it's a similar halogen nation process. But when there is an excess of halogen, then the same addition can happen twice, right? So if I take an all kind here with a triple wand and I react this with one mole of halogen, then I'm going to end up with two halogen atoms on adjacent cartin, right? But I'm still going to have a double bond in between my two carbons here. So when there is an excess of halogen present, then addition can happen twice, right? So two more carbons or two more halogens, excuse me, can add on to both carbons of the starting all kind. So that is exactly what's happening here, right? Because I have too much, but because I have four chlorine atoms on two adjacent carbons, then those two carbons must have had a triple bond in between them. So for the identity of the all kind, right, it's still going to be a six carbon chain, but there will be a double bond in between or triple bond, excuse me, in between carbon three and four. So there you have it. So now with respect to the name, right, this is a six carbon pairing chain, right? So the base name would be hexane, but because there is a triple bond in this molecule, the suffix A&E gets replaced with Y and E. So that's heck sign, right? However, I still have to specify where the triple bond is. So because the triple bond is in between carbons three and four, I would use the smaller number in my Iupac name and I can do so in between the prefix XX and the suffix Yne. So that is hex dash three dash I with dashes to separate numbers from letters and there you have it. If I scroll up one more time, then the achy required to produce 3344 Tetra Chloro exane from an excess of CL two was hex three in. So with that being said, thank you so very much for watching and I hope you found this helpful.

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13. Alkenes, Alkynes, and Aromatic Compounds

Halogenation Reaction

GOB Chemistry

13. Alkenes, Alkynes, and Aromatic Compounds

Halogenation Reaction

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Problem 61

Textbook Question

2,2,3,3-Tetrabromopentane can be prepared by an addition reaction of excess Br₂ with an alkyne. Draw the structure of the alkyne and name it.

Verified step by step guidance

Identify the product structure: The given compound, 2,2,3,3-Tetrabromopentane, has four bromine atoms attached to the second and third carbons of a pentane chain. This indicates that the starting alkyne must have a triple bond between the second and third carbons, as bromine adds across the triple bond in an addition reaction.

Determine the alkyne structure: To form 2,2,3,3-Tetrabromopentane, the alkyne must have five carbon atoms in total, with the triple bond located between the second and third carbons. The structure of the alkyne is CH3-C≡C-CH2-CH3.

Name the alkyne: The IUPAC name for the alkyne is 2-pentyne. The numbering starts from the end of the chain closest to the triple bond to give the lowest possible number to the triple bond.

Explain the reaction: When excess Br2 reacts with an alkyne, the bromine molecules add across the triple bond in two steps. First, the triple bond is converted to a double bond with two bromine atoms added. Then, the double bond reacts with more Br2 to form a single bond with four bromine atoms added in total.

Verify the product: After the addition of excess Br2 to 2-pentyne, the final product is 2,2,3,3-Tetrabromopentane, confirming that the starting alkyne is correctly identified as 2-pentyne.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Alkynes

Alkynes are hydrocarbons that contain at least one carbon-carbon triple bond. They are unsaturated compounds characterized by the general formula CnH2n-2. The presence of the triple bond gives alkynes unique reactivity, making them suitable for various addition reactions, such as halogenation with bromine.

Addition Reactions

Addition reactions involve the addition of atoms or groups to a molecule, typically across a double or triple bond. In the case of alkynes, the triple bond can react with halogens like Br2, resulting in the formation of a saturated compound. This type of reaction is crucial in organic synthesis for modifying molecular structures.

Bromination

Bromination is a specific type of addition reaction where bromine (Br2) is added to a compound. For alkynes, this process can lead to the formation of dibrominated products, such as 2,2,3,3-tetrabromopentane. Understanding bromination is essential for predicting the products of reactions involving alkynes and for naming the resulting compounds.

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