Alkyl Group Migration
Alkyl Group Migration - Related Videos
02:45
Alkyl Halides
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2023
Structural Properties Alkyl halides are halogen-substituted alkanes wherein one or more hydrogen atoms of an alkane is replaced by a halogen atom such as fluorine, chlorine, bromine, or iodine. The carbon atom in an alkyl halide is bonded to the halogen atom, which is sp3-hybridized and exhibits a tetrahedral shape. Unlike alkyl halides, compounds in which a halogen atom is bonded to an sp2 -hybridized carbon atom of a carbon-carbon double bond (C=C) are called vinyl halides. Whereas aryl...
07:07
Assessment of Endothelial Cell Migration After Exposure to Toxic Chemicals
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Cited by 9 •
2015
Investigation of early endothelial cell (EEC) migration is important to understand the pathophysiology of certain illnesses and to potentially identify novel strategies for therapeutic intervention. The following protocol describes techniques to assess cell migration that have been adapted for the investigation of EEC.
02:27
Preparation of Alkynes: Alkylation Reaction
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2025
Introduction Alkylation of terminal alkynes with primary alkyl halides in the presence of a strong base like sodium amide is one of the common methods for the synthesis of longer carbon-chain alkynes. For example, treatment of 1-propyne with sodium amide followed by reaction with ethyl bromide yields 2-pentyne. The reaction takes place in two steps: 1. The first step is the deprotonation of the terminal alkyne by the strong base forming an acetylide ion. 2. The second step is a nucleophilic...
08:24
The Transwell Migration Assay
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2023
Cells migration in response to chemical cues is crucial to development, immunity and disease states such as cancer. To quantify cell migration, a simple assay was developed in 1961 by Dr. Stephen Boyden, which is now known as the transwell migration assay or Boyden chamber assay. This set-up consists an insert which separates the wells of a multiwell plate into top and bottom compartments. Cells whose migration is to be studied are seeded into the top compartment and the chemoattractant...
01:22
Mass Spectrometry: Alkyl Halide Fragmentation
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2025
Chlorine isotopes exist as 35Cl and 37Cl in a 3:1 ratio, while bromine isotopes exist as 79Br and 81Br in a 1:1 ratio. The mass spectrum of alkyl halides typically produces two distinct molecular ion peaks, the molecular ion peak, [M], and the molecular ion plus two, [M + 2] peak. The relative heights of these two peaks are proportional to the isotopic abundance ratios of the halide. For example, 2‐chloropropane and 1‐bromopropane display two peaks with relative peak heights in a 3:1 and 1:1...
FAQs
In a typical 1,2-shift, the alkyl group moves to a neighboring electron-deficient center while carrying the electron pair from its original bond. The original bond therefore breaks as a new bond forms at the adjacent site. This coordinated movement changes the molecular skeleton and can produce a structure with a more stable or more reactive arrangement.
Migration can place the alkyl group at an adjacent electron-deficient position while reorganizing the carbon framework. In reactions that proceed through or involve carbocation stabilization, this rearrangement may lead to a more stable carbocation-containing structure. That stabilization helps explain why migration can influence which product structure forms under particular reaction conditions.
The group that migrates is not selected independently of the substrate or reaction environment. Migration aptitude helps determine which alkyl substituent moves, while stereochemistry describes how the three-dimensional arrangement changes during that movement. Because both depend on the substrate and reaction conditions, different starting structures can produce different rearranged products.
An alkyl group migration changes connectivity within the molecule rather than merely modifying an existing functional feature. The moving substituent transfers its bonding electron pair to a neighboring electron-deficient center, so the carbon skeleton is reorganized. This distinction matters when predicting products, because the rearranged framework may be more stable or more reactive than the starting arrangement.
Product prediction begins by identifying the migrating alkyl substituent, the neighboring electron-deficient center, and the bond whose electron pair moves during the 1,2-shift. Chemists then consider migration aptitude, stereochemistry, substrate structure, and reaction conditions. These factors help determine the new molecular connectivity and whether the rearrangement produces a more stable or reactive structure.
These rearrangements are useful when a synthesis requires deliberate reorganization of a carbon framework. By changing molecular connectivity, they help chemists construct structures that may be difficult to obtain without rearrangement. Their value extends to designing selective synthetic routes, where migration aptitude, stereochemistry, substrate features, and reaction conditions guide the desired product structure.
The Wagner–Meerwein and pinacol rearrangements are important reaction classes in which alkyl group migration underpins molecular reorganization. They provide examples of how a substituent can shift within a reacting structure while changing the carbon framework. Studying these reactions connects the general 1,2-shift mechanism with practical strategies for predicting products and planning synthesis.
Analyzing a migration reveals how the substrate, electron-deficient center, and reaction conditions influence molecular reorganization. It can indicate which carbon framework is favored, which substituent is likely to move, and how stereochemistry may affect the outcome. This information supports interpretation of product structures and helps chemists evaluate whether a rearrangement can contribute to a selective synthetic route.