유기화학실험2 prelab_ Diphenylacetylene from Stilbene

문서 내 토픽

1. Bromination of stilbene

실험 A에서는 (E)-stilbene을 bromination하여 meso-1,2-dibromo-1,2-diphenylethane을 합성한다. 이 반응에서는 bromonium ion intermediate가 형성되며, C=C가 Br2에 친핵체로 작용하여 Br2의 결합을 끊고 Br-를 만든다. 이 과정에서 bridged bromonium ion이 C+형태의 중간체를 만들며 안정해진다.
2. Diphenylacetylene synthesis

실험 B에서는 실험 A에서 얻은 meso-1,2-dibromo-1,2-diphenylethane을 이용하여 diphenylacetylene을 합성한다. 이 반응에서는 E2 반응이 두 번 일어나는데, OH-가 strong base로 작용하여 H+를 가져오고 Br을 good leaving group으로 만들어 내보낸다. 이 과정이 2회 반복되며 diphenylacetylene을 만들어낸다.
3. Stereospecificity

Stereospecificity란 출발 물질의 stereo chemistry가 생성물의 stereochemistry에 영향을 미쳐 특정 product만을 생성해내는 것을 말한다. 실험에서는 meso compound인 1,2-dibromo-1,2-diphenylethane이 생성되는데, 이는 tetrahedral stereogenic centers를 갖는 achiral compound이다.
4. TLC analysis

실험에서는 hexane:MC = 2:1의 eluent로 starting material, 실험 A의 product, 실험 B의 product, co spot을 만들어 TLC를 전개하고, UV visualization으로 결과를 확인한다. 분자량이 클수록 고정상과 더 상호작용하여 Rf값이 낮게 나올 것이다.
5. Pyridinium bromide perbromide

실험에서는 pyridinium bromide perbromide를 이용하는데, 이는 질량을 용이하게 잴 수 있고 실온에서 안정하기 때문에 다루기가 편하다.

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1. Bromination of stilbene

Bromination of stilbene is an important organic reaction that involves the addition of bromine molecules to the carbon-carbon double bond of the stilbene molecule. This reaction is commonly used in organic synthesis to introduce bromine atoms into organic compounds, which can then be further functionalized or used as intermediates in the synthesis of more complex molecules. The stereochemistry of the reaction is an important consideration, as the addition of bromine can occur in either a cis or trans orientation relative to the existing substituents on the double bond. Understanding the factors that influence the stereochemical outcome of the bromination reaction, such as the reaction conditions, the presence of catalysts or other additives, and the nature of the starting material, is crucial for controlling the product distribution and optimizing the synthesis. Additionally, the bromination of stilbene can be used as a model system to study the mechanisms and kinetics of electrophilic addition reactions, which are fundamental to organic chemistry.
2. Diphenylacetylene synthesis

The synthesis of diphenylacetylene is an important reaction in organic chemistry, as it allows for the preparation of a versatile building block for the construction of more complex organic molecules. Diphenylacetylene is a symmetrical alkyne compound with two phenyl groups attached to the carbon-carbon triple bond. The synthesis of diphenylacetylene typically involves the dehydrohalogenation of a dihalogenated precursor, such as 1,1-diphenyl-2,2-dibromoethene, or the Sonogashira coupling reaction between iodobenzene and phenylacetylene. The choice of synthetic route and the specific reaction conditions can have a significant impact on the yield and purity of the final product. Understanding the factors that influence the reactivity and selectivity of these reactions, such as the nature of the starting materials, the choice of catalysts or reagents, and the reaction conditions, is crucial for developing efficient and reliable synthetic methods for diphenylacetylene and related alkyne compounds. These compounds have a wide range of applications in organic synthesis, materials science, and other fields, making the development of robust and scalable synthetic methods an important area of research.
3. Stereospecificity

Stereospecificity is a fundamental concept in organic chemistry that describes the ability of a chemical reaction to preserve the stereochemical configuration of the reactants in the products. This is an important consideration in the synthesis of chiral molecules, as the stereochemistry of a compound can have a significant impact on its physical, chemical, and biological properties. Understanding the factors that influence the stereospecificity of a reaction, such as the reaction mechanism, the presence of chiral auxiliaries or catalysts, and the steric and electronic properties of the reactants, is crucial for the development of efficient and selective synthetic methods. The study of stereospecificity also provides insights into the underlying principles of organic reactivity and can be used to design new reactions and strategies for the synthesis of complex, stereochemically-defined molecules. Overall, the concept of stereospecificity is a fundamental aspect of organic chemistry that has far-reaching implications for the synthesis of pharmaceuticals, natural products, and other important classes of compounds.
4. TLC analysis

Thin-layer chromatography (TLC) is a widely used analytical technique in organic chemistry that allows for the separation, identification, and purification of organic compounds. TLC analysis is a powerful tool for monitoring the progress of chemical reactions, determining the purity of reaction products, and identifying the components of complex mixtures. The technique relies on the differential partitioning of compounds between a stationary phase (typically a silica or alumina-based adsorbent) and a mobile phase (a solvent or solvent mixture). By carefully selecting the appropriate stationary and mobile phases, as well as the experimental conditions, it is possible to achieve effective separation and characterization of a wide range of organic compounds. TLC analysis provides valuable information about the polarity, solubility, and reactivity of the compounds under investigation, which can be used to guide the development of synthetic strategies, purification methods, and analytical procedures. The simplicity, versatility, and cost-effectiveness of TLC make it an indispensable tool in the arsenal of organic chemists, and its continued evolution and integration with other analytical techniques, such as mass spectrometry and NMR spectroscopy, ensures its ongoing relevance in modern organic chemistry research and practice.
5. Pyridinium bromide perbromide

Pyridinium bromide perbromide (PBP) is a versatile reagent in organic synthesis, commonly used for the bromination of organic compounds. PBP is a crystalline solid that acts as a source of electrophilic bromine, making it a useful alternative to elemental bromine or other bromine-containing reagents. The advantages of using PBP include its ease of handling, stability, and selectivity in certain bromination reactions. PBP can be employed in a wide range of organic transformations, such as the bromination of alkenes, aromatic compounds, and heterocycles, as well as in the oxidation of alcohols to aldehydes or ketones. The reactivity and selectivity of PBP-mediated brominations can be influenced by factors such as the nature of the substrate, the reaction conditions, and the presence of other functional groups. Understanding the mechanisms and scope of PBP-mediated reactions is crucial for developing efficient and selective synthetic methods, as well as for exploring new applications of this versatile reagent in organic chemistry. Overall, pyridinium bromide perbromide is an important tool in the synthetic chemist's toolkit, with the potential to enable the synthesis of a diverse range of bromine-containing organic compounds.