Markovnikovand Anti-Markovnikov Addition of Hydrochloric Acid to Styrene
Start Date
23-4-2026 12:00 AM
Description
Markovnikov and Anti-Markovnikov additions describe organic reactions where a halide (group 7 element) bonded to a hydrogen is added to a double bond, resulting in its elimination. Markovnikov addition describes where the halide bonds to the more stable carbon and the hydrogen to the less stable carbon of the double bond. In an Anti-Markovnikov addition, the placement is reversed by the addition of peroxide. While these mechanisms are well established, Lindenwood does not currently have a lab experiment demonstrating the different effects. The goal of this project was to develop a lab that demonstrates the differences. The additions were performed on styrene because its stable ring structure directs to the remaining double bond. This double bond has vinyl carbons that are classified as primary and secondary benzyllic. There being a large difference between the stability of the potential carbocations being formed should result in two very distinctly different products. This difference could be easily determined by IR and NMR analysis. Hydrochloric acid (HCl) was used due to its liquid form and prevalence. The products of both syntheses were distilled, then analyzed by IR spectroscopy to confirm the products. NMR analysis was unable to be run due to time restraints.
Research Highlights
The Problem: Lindenwood University currently lacks a laboratory experiment to reinforce classroom lectures regarding Markovnikov and anti-Markovnikov addition mechanisms.
The Method: Researchers developed a procedure using styrene and hydrochloric acid to synthesize 1-chloroethylbenzene and 2-chloroethylbenzene, utilizing fractional distillation for purification and infrared (IR) spectroscopy for product identification.
Quantitative Finding: The experimental procedure utilizes 2.5 ml of styrene, 5.5 ml of 35% hydrochloric acid, and 5.5 ml of acetic acid for Markovnikov addition; 1.75 ml of 35% hydrogen peroxide is added to achieve anti-Markovnikov addition.
Finding: IR spectroscopy confirmed the synthesis of the desired products, though samples exhibited solvent contamination from benzene and toluene; a transition from benzene to toluene as a solvent was implemented to enhance student safety during the procedure.
Recommended Citation
Malawey, Justin, "Markovnikovand Anti-Markovnikov Addition of Hydrochloric Acid to Styrene" (2026). 2026 Student Academic Showcase. 14.
https://digitalcommons.lindenwood.edu/src_2026/Posters/1/14
Markovnikovand Anti-Markovnikov Addition of Hydrochloric Acid to Styrene
Markovnikov and Anti-Markovnikov additions describe organic reactions where a halide (group 7 element) bonded to a hydrogen is added to a double bond, resulting in its elimination. Markovnikov addition describes where the halide bonds to the more stable carbon and the hydrogen to the less stable carbon of the double bond. In an Anti-Markovnikov addition, the placement is reversed by the addition of peroxide. While these mechanisms are well established, Lindenwood does not currently have a lab experiment demonstrating the different effects. The goal of this project was to develop a lab that demonstrates the differences. The additions were performed on styrene because its stable ring structure directs to the remaining double bond. This double bond has vinyl carbons that are classified as primary and secondary benzyllic. There being a large difference between the stability of the potential carbocations being formed should result in two very distinctly different products. This difference could be easily determined by IR and NMR analysis. Hydrochloric acid (HCl) was used due to its liquid form and prevalence. The products of both syntheses were distilled, then analyzed by IR spectroscopy to confirm the products. NMR analysis was unable to be run due to time restraints.