The addition of HCl to 3-hexyne occurs as an anti-addition.Give the structure ,stereochemistry and name of the product.

When hydrochloric acid (HCl) is added to 3-hexyne, the reaction proceeds through an anti-addition mechanism, resulting in a specific product. Let's break down the process step by step to understand the structure, stereochemistry, and name of the resulting compound.

Understanding the Reaction

3-Hexyne is an alkyne with the formula C₆H₁₀ and has a triple bond between the second and third carbon atoms. When HCl is added to this alkyne, the reaction involves the electrophilic addition of H⁺ from HCl to one of the carbon atoms in the triple bond, followed by the addition of Cl^- to the other carbon atom.

Mechanism of Addition

• The triple bond acts as a nucleophile, attacking the proton (H⁺) from HCl.
• This results in the formation of a carbocation intermediate at the more substituted carbon (C-2).
• Next, the chloride ion (Cl^-) attacks the carbocation, leading to the final product.

Product Structure

The product formed from this reaction is 2-chloro-3-hexene. The structure can be represented as follows:

Stereochemistry of the Product

Due to the anti-addition mechanism, the chlorine atom and the hydrogen atom are added to opposite sides of the double bond. This results in a specific stereochemistry for the double bond in 2-chloro-3-hexene. The product can exist as two geometric isomers: the E (trans) and Z (cis) forms.

Naming the Compound

The IUPAC name for the product is 2-chloro-3-hexene. The "2-chloro" indicates the position of the chlorine substituent, while "3-hexene" refers to the hexene chain with the double bond starting at the third carbon.

Summary of Key Points

• Starting material: 3-hexyne (C₆H₁₀)
• Reagent: HCl
• Product: 2-chloro-3-hexene
• Stereochemistry: Anti-addition leading to E and Z isomers

This reaction exemplifies how the addition of HCl to an alkyne can lead to a product with specific stereochemical characteristics, showcasing the fascinating behavior of organic compounds during chemical reactions.