PPT-Aromaticity

and the Novel BoronNitrogen Bond A Benzene Mimic Jeremy Schifberg Liu Group Background Aromaticity Definition A chemical property whereby a conjugated ring exhibits a strongerthanexpected stabilization due to its electrons being free to cycle around the ring atoms A hybrid of a single and a double bond is formed with each bond in the ring identical to the next. brPage 2br Figure 2 MBIUS AROMATICITY IN TRANSITION STATES brPage 3br Scheme 1 HO HO Figure 3 brPage 4br ELUCIDATION OF THE FIRST M BIUS AROMATIC INTERMEDIATE exo Scheme 2 SYNTHESIS OF THE FIRST MBIUS AROMATIC MOLECULE 7 Figure 4 Cl OH Cl brPage 5br Dr. . Sheppard. CHEM . 2412. Summer 2015. Klein (2. nd. ed. .) . sections. : 18.1, 18.2, 18.8, 18.3, 18.4, 18.5. Aromatic Compounds. Originally distinguished because of smell. Then noticed trends in reactivity. Aromaticity. TNT. 8-methyl-N-vanillyl-6-nonenamide (. Capsaicin). Buckminsterfullerene. Key points & objectives:. Aromatic molecules are cyclic, conjugated, flat, and unusually stable. 4n + 2 electrons (. M.ARULSELVAN. Syllabus. Benzene and Aromaticity. 4.1 Concept of aromaticity:. . . -Huckel's rule for aromaticity, . -identification of aromatic, . -Non-aromatic and anti aromatic systems based on planarity, conjugation and Huckel's rule.. (. Benzene. ). 140 pm. 140 pm. 140 pm. 140 pm. 140 pm. 140 pm. All C—C bond distances = 140 pm. Benzene. empirical formula. = CH. 140 pm. 140 pm. 140 pm. 140 pm. 140 pm. 140 pm. . 146 pm. 134 pm. Conjugation and Aromaticity. Which resonance form contributes more? .  . A B C D. A = C > B E. B > A = C. Conjugation and Aromaticity. Do you expect a difference in bond lengths?.  . a. yes b. no. at the nucleus From equation (2), it is clear that a radiation of frequency & = "B0/2! possess the right amount of energy to effect a transition from lower energy state to higher energy $ state. Abso Aromaticity. of . Metallasilapentalynes. Advisor: Jun Zhu Reporter: . Xuerui. Wang. Outline. Background . Computational Method. Results and Discussion. Conclusion . Background. 1982. Thorn ,D , L.; Hoffman, R. . Heterocyclic. Chemistry. Heterocyclic. Chemistry. Five-. membered. . Heterocycles. Pyrrole. , Furan and . Thiophene. Heterocyclic Chemistry. Five Membered Heterocycles-Introduction. The main reason for the study of pyrrole came from the work on the structure of haem; the blood respiratory pigment, and the chlorophyll; the green photosynthetic pigment of plants..