[서강대 유기화학실험 A+ 레포트] Exp11.Wittig-Horner Reaction

문서 내 토픽

1. Wittig Reaction

Wittig reaction은 ketone 또는 aldehyde를 phosphorus ylide와 반응시켜 alkene을 만드는 반응입니다. 이 반응은 알데히드나 케톤을 알켄으로 전환하는데 사용됩니다. 반응 결과 O-P 사이의 결합이 만들어지며, 이 결합이 반응의 driving force 역할을 합니다. 반응 메커니즘은 ylide 탄소 원자가 카보닐 탄소를 공격하여 betaine intermediate를 형성하고, 이후 oxaphosphetane을 거쳐 alkene과 triphenylphosphine oxide가 생성됩니다.
2. Wittig-Horner Reaction

Wittig-Horner 반응은 Wittig 반응과 유사하게 ketone 또는 aldehyde를 alkene으로 전환할 수 있습니다. 다만 phosphorus ylide 대신 phosphonate-stabilized carbanion을 사용합니다. 이 반응에서는 E-alkene만 선택적으로 생성됩니다. 반응 메커니즘은 phosphonate ester와 강염기의 반응으로 phosphonate-stabilized carbanion이 형성되고, 이것이 aldehyde와 반응하여 E-alkene을 생성합니다.
3. Karplus Equation

Karplus 방정식은 NMR에서 J-coupling constant와 dihedral torsion angle 간의 관계를 나타내는 식입니다. 이 식을 통해 NMR 결과에서 관찰된 J-coupling constant로부터 dihedral angle을 계산할 수 있으며, 이를 바탕으로 화합물의 입체구조를 예측할 수 있습니다. 본 실험에서는 olefin proton의 coupling constant를 구하여 cis와 trans 여부를 확인하였습니다.
4. Bothner-By Equation

Bothner-By 방정식 또한 NMR에서 J-coupling constant와 dihedral torsion angle 간의 관계를 나타내는 식입니다. Karplus 방정식과 함께 사용하면 화합물의 입체구조를 보다 정확히 예측할 수 있습니다.
5. 실험 과정

본 실험에서는 NaOMe와 dry DMF를 반응시켜 phosphonate-stabilized carbanion을 만든 후, 이를 cinnamaldehyde와 반응시켜 trans,trans-1,4-Diphenyl-1,3-butadiene를 생성하였습니다. 실험 과정에서 수분 유입을 막기 위해 N2 gas를 사용하였고, 생성물 분리 시 용해도 차이를 이용하였습니다. 생성물의 순도와 구조는 TLC, NMR, IR 분석을 통해 확인하였습니다.

Easy AI와 토픽 톺아보기

1. Wittig Reaction

The Wittig reaction is a powerful organic chemistry tool that allows for the synthesis of alkenes from aldehydes or ketones and phosphorus ylides. It is a highly versatile reaction that can be used to construct a wide range of alkene-containing compounds, including many natural products and pharmaceuticals. The reaction proceeds through the formation of a betaine intermediate, which then collapses to form the desired alkene product. One of the key advantages of the Wittig reaction is its ability to selectively form either the E or Z isomer of the alkene, depending on the specific reaction conditions and the nature of the starting materials. This selectivity makes the Wittig reaction a valuable tool for the stereoselective synthesis of complex organic molecules. Overall, the Wittig reaction is an important and widely used transformation in organic chemistry, with applications in both academic and industrial settings.
2. Wittig-Horner Reaction

The Wittig-Horner reaction is a variation of the classic Wittig reaction, which is used to synthesize alkenes from aldehydes or ketones and phosphorus ylides. The Wittig-Horner reaction uses a phosphonate ester instead of a phosphonium ylide, which can offer some advantages in terms of reactivity and selectivity. One key advantage of the Wittig-Horner reaction is that it can often be carried out under milder conditions compared to the traditional Wittig reaction, which can be important for the synthesis of sensitive or complex molecules. Additionally, the Wittig-Horner reaction can sometimes provide better control over the stereochemistry of the alkene product, with a preference for the E-isomer in many cases. Overall, the Wittig-Horner reaction is a valuable tool in the organic chemist's toolbox, complementing the classic Wittig reaction and providing additional options for the stereoselective synthesis of alkenes.
3. Karplus Equation

The Karplus equation is a fundamental tool in organic chemistry and nuclear magnetic resonance (NMR) spectroscopy. It describes the relationship between the dihedral angle of a molecule and the magnitude of the scalar coupling constant (J-coupling) between the corresponding nuclei. This relationship is particularly important for understanding the stereochemistry and conformational preferences of organic molecules, as the J-coupling values observed in NMR spectra can provide valuable information about the three-dimensional structure of a compound. The Karplus equation has been extensively studied and refined over the years, and it has found widespread application in the structural elucidation of complex organic molecules, the determination of stereochemistry, and the analysis of conformational dynamics. As a result, the Karplus equation is considered an essential part of the organic chemist's toolkit, enabling the interpretation of NMR data and the deduction of important structural features of molecules.
4. Bothner-By Equation

The Bothner-By equation is a mathematical expression that relates the chemical shift difference between two coupled nuclei in an NMR spectrum to the dihedral angle between the corresponding bonds in the molecular structure. This relationship is particularly useful for determining the stereochemistry and conformational preferences of organic molecules. The Bothner-By equation builds upon the Karplus equation, which describes the relationship between dihedral angle and scalar coupling constant (J-coupling), by providing a similar correlation for the chemical shift difference (Δδ) between coupled nuclei. The Bothner-By equation has found widespread application in the structural elucidation of complex organic compounds, as the chemical shift differences observed in NMR spectra can provide valuable information about the three-dimensional arrangement of atoms within a molecule. Overall, the Bothner-By equation is an important tool in the field of organic chemistry, complementing the Karplus equation and enabling a more comprehensive understanding of molecular structure and conformation.
5. 실험 과정

실험 과정은 화학 연구에 있어 매우 중요한 부분입니다. 실험 과정을 통해 이론적 지식을 실제로 검증하고, 새로운 발견을 할 수 있기 때문입니다. 실험 과정에는 실험 설계, 실험 수행, 데이터 수집 및 분석, 결과 해석 등 다양한 단계가 포함됩니다. 각 단계에서 주의 깊은 관찰과 정확한 기록이 필요하며, 실험 오류를 최소화하기 위한 노력이 요구됩니다. 또한 실험 결과를 바탕으로 가설을 검증하고, 새로운 가설을 제시하는 과정이 중요합니다. 실험 과정은 화학 연구의 핵심이며, 실험 기술의 숙련도와 창의성이 연구 성과에 큰 영향을 미칩니다. 따라서 화학자들은 실험 기술을 지속적으로 향상시키고, 실험 과정에서 발생할 수 있는 문제를 해결하는 능력을 갖추어야 합니다.