Thermal Rearrangement
Thermal Rearrangement - Related Videos
![[3,3] Sigmatropic Rearrangement of 1,5-Dienes: Cope Rearrangement](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2Ffiles%2Fmedia%2Fscience-education%2Fscience-education-thumbs%2F12422.jpg%3Fv%3D2026-08-11%252008%253A27%253A10&w=750&q=75)
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[3,3] Sigmatropic Rearrangement of 1,5-Dienes: Cope Rearrangement
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2023
The Cope rearrangement is classified as a [3,3] sigmatropic shift in 1,5-dienes, leading to a more stable, isomeric 1,5-diene. The reaction involves a concerted movement of six electrons, four from two π bonds and two from a σ bond, via an energetically favorable chair-like transition state. From a molecular orbital perspective, the rearrangement can be viewed as the interaction between the ground state frontier orbitals of the allyl anion and cation. Under thermal conditions, the two π...
![[3,3] Sigmatropic Rearrangement of Allyl Vinyl Ethers: Claisen Rearrangement](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2Ffiles%2Fmedia%2Fscience-education%2Fscience-education-thumbs%2F13097.jpg%3Fv%3D2026-08-11%252008%253A27%253A10&w=750&q=75)
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[3,3] Sigmatropic Rearrangement of Allyl Vinyl Ethers: Claisen Rearrangement
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2023
The Claisen rearrangement is a [3,3] sigmatropic rearrangement of allyl vinyl ethers to unsaturated carbonyl compounds. The rearrangement is a concerted pericyclic reaction proceeding via a chair-like transition state. An aromatic Claisen rearrangement involves the conversion of allyl aryl ethers to an unstable ketone intermediate, which tautomerizes to give ortho-substituted phenols. However, ortho-substituted allyl aryl ethers exclusively yield para-substituted phenols via two sequential...
09:42
Analysis of Thermal Expansion via Dilatometry
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2023
Source: J. Jacob Chavez, Ryan T. Davis, and Taylor D. Sparks, Department of Materials Science and Engineering, The University of Utah, Salt Lake City, UT Thermal expansion is extremely important when considering which materials will be used in systems that experience fluctuations in temperature. A high or low thermal expansion in a material may or may not be desirable, depending on the application. For instance, in a common liquid thermometer, a material with a high thermal expansion would be...
01:57
Preparation of Diols and Pinacol Rearrangement
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2023
Compounds bearing two hydroxyl groups are known as diols. When the hydroxyl groups are located on adjacent carbon atoms, the diols are called vicinal diols or glycols. Under acidic conditions, vicinal diols undergo a specific reaction called pinacol rearrangement. The reaction begins with transferring a proton from the acid catalyst to one of the hydroxyl groups, producing an oxonium ion. In the second step, the oxonium ion loses H2O, forming a tertiary carbocation intermediate. In the...
10:32
Thermal Diffusivity and the Laser Flash Method
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2023
Source: Elise S.D. Buki, Danielle N. Beatty, and Taylor D. Sparks, Department of Materials Science and Engineering, The University of Utah, Salt Lake City, UT The laser flash method (LFA) is a technique used to measure thermal diffusivity, a material specific property. Thermal diffusivity (α) is the ratio of how much heat is conducted relative to how much heat is stored in a material. It is related to thermal conductivity (), how much heat is transferred through a material due to a temperature...
FAQs
The mechanism depends on how the molecule reorganizes after receiving thermal energy. In a concerted pathway, bond cleavage and bond formation occur in a coordinated sequence through a favorable transition state. Other reactions first generate reactive intermediates, which then undergo further changes. Distinguishing these possibilities helps chemists interpret product formation and predict how structural features influence reactivity.
Temperature supplies the energy needed to access a favorable transition state or form a reactive intermediate. As conditions change, competing pathways may become more or less accessible, influencing which connectivity or stereochemistry predominates. Studying temperature dependence therefore helps researchers evaluate reaction behavior and choose conditions that favor the desired molecular reorganization.
The arrangement of atoms and functional groups determines which bonds can reorganize and which transition state is most favorable. Structural differences can therefore affect both the connectivity and stereochemistry of the product. Examining these relationships allows chemists to connect molecular structure with chemical reactivity and design rearrangements that produce specific isomers or molecular frameworks.
A study begins with a suitable starting material, followed by heating to provide the thermal energy required for molecular reorganization. Researchers then examine the resulting compound or compounds to determine changes in connectivity and stereochemistry. Comparing outcomes across temperatures can reveal temperature dependence, selectivity, and evidence consistent with a concerted pathway or reactive intermediates.
Chemists use this strategy when a readily available starting material can be converted into a more useful isomer or structurally complex product. The transformation may relocate a functional group, change molecular connectivity, or help construct a larger framework. These capabilities make rearrangement reactions valuable when planning synthetic routes that depend on controlled changes in molecular structure.
Such investigations can show how heating changes reaction behavior, which products are favored, and whether the transformation affects connectivity, stereochemistry, or both. Temperature studies also contribute to mechanistic analysis by indicating how a reaction responds to thermal conditions. In synthetic chemistry, these observations support more efficient route design and improve understanding of structure-dependent reactivity.