69080 - Organic Chemistry II

Learning outcomes

After completion of this course students know basic methodologies for the preparation of aromatic and aliphatic organic molecules by applying concepts on the chemistry of aromatic compounds, carbonyl compounds and carboxylic acid derivatives. Students will be able to discuss the stereochemical features and anticipate structure reactivity correations in a molecule of medium complexity. They will also have basic knowledge of the most common classes of organic natural products and will be able to perform simple trasformations on them.

Course contents

Prerequisites: to attend profitably this course student should have passed the exam of general chemistry, being familiar with the concepts of acid-base equilibria, chemical bond, chemical Equilibrium and reaction rate, and possibly have passed the exam of organic chemistry I, already possessing a good background in structure-reactivity correlations of the most common functional groups.

Program

I Semester

The chemistry of aromatic compounds:

·        Valence bond (resonance) and LCAO qualitative treatment of the delocalized bond. P bonds in ethylene, allyl systems (free-radical, cation, anion), 1,3-butadiene and conjugated polyenes. Hydrogenation and combustion heat in the experimental determination of delocalization energy.

·        Aromaticity, Frost circle, main classes of aromatic compounds, from benzene to heteraromatic compounds, polycyclic aromatic hydrocarbons up to graphite, fullerene and nanotubes.

·       The reactivity of aromatic compounds: electrophilic aromatic substitution, nucleophilic aromatic substitution, substituent effect on reaction rates and regioselectivity.

·        Benzene derivatives: main redox processes  and interconversion reactions between benzene derivatives. Cross-coupling reactions to diphenyls, an introduction.

Chemistry of carbonyl compounds and carboxylic acids

·        Carbonyl compounds, carboxylic acids, their derivatives and interconversions. 

·        Keto-enol tautomerism and analogous heteroallylic rearrangements.

·        Acid- and base-catalyzed aldol reaction, inter- ed intramolecular aldol reactions, aldol dehydration. Enamine-based organocatlytic aldol reactions. Mannich and Strecker reactions

·        Malonic and acetoacetic synthesis.

·        Regioselective formation of enolates in unsymmetrically substituted ketones. Stereoselective formation of E or Z enolates of ketones or esters.

·        Alkylating agents. C/O Alkylation of enolates, solvent effect, hard-soft properties of alkylating agents.

·       Two-step aldol reaction. Stereocontrolled reactions and Zimmermann-Traxler mecahnism with lithium and boron enolates. Analogy with the chemistry of allyl boron reagents.

·        Enolate acylation: one-pot reactions (Claisen, Dieckman) and two-step procedures via preformed enolates.

·        a ,β-unsaturated carbonyl compounds and carboxylic acid derivatives: resonance and molecular orbital treatment; 1,2 vs 1,4 addition (Michael and analogous reactions). Sequential one-pot  tricomponent reactions based on conjugate addition processes.

·        Silyl enol ethers and their applications in carbon-carbon bond forming reactions.

·        Short survey on umpolung reagents; alfa-haloketones, aliphatic nitrocompounds, isonitriles, cyanide ion.

Rearrangements.

·        [1,2] Migrations to electron poor centers

·        [1,2] and [3,2] Migrations to electron-rich centers.

·        Pericyclic reactions, definitions.

·        [3,3] Cope, Claisen and related sigmatropic rearrangements. Applications in organic synthesis.

II Semester

Stereochemistry:

·        Classification of isomers.

·        Compounds containing more stereogenic centers. Meso compounds.

·        Homotopic, enantiotopic and distareotopic groups

·        Planar molecules with h omotopic, enantiotopic and distareotopic faces.

·        Axial chirality

·        Planar chirality.

Crabohydrates

·        Monosaccharides: structure, stereochemistry, Fisher projections.

·        Furanosides and pyranosides; emiacetal structures. Mutarotation.

·        Enediol tautomerism. Aldol reaction of dihydroxyacetone and glyceraldehyde.

·        Kiliani-Fisher synthesis of monosaccharides.

·        Analysis of monosaccharides.

·        Monosaccharide derivatives. Glucuronic acid and detoxification mechanisms.

·        Most common di- and polysaccharides.

Nucleic acids

·        Nucleobases, structures, tautomeric forms, hydrogen bonding.

·        Nucleosides and nucleotides.

·        Examples of oxidative damage of DNA.

·        ATP, cGMP, coenzyme A, NADPH.

·        Simple and double strands. Double helix structure of DNA

Aminoacids and peptides:

·        Proteinogenic alfa-aminoacids: classification, structure, physical properties (pI, titration curve, electrophoresis)

·        Preparation of racemic alfa-aminoacids and racemate resolution. Enenatioselective syntheses.

·        Peptide bond. Synthesis of a dipeptide. Protective groups for NH2 e COOH groups. Coupling agents.

·        Primary structure of a peptide, Edman degradation.

·        Secondary, tertiary and quaternary structure of proteins.

·        Protein roles in biology.

Lipids:

·        Fatty acids, structure, physical properties. Micelles and surfactants. Neutral surfactants.

·        Fatty acids biogenesis.

·        Triacyl glycerols, saponification.

·        Phospholipids bilayres, liposomes and membranes.

Readings/Bibliography

Lessons handouts and presentations are  available to students who can deepen the course topics using recommended books such as:

• W.H.Brown, B.L.Iverson, E.V.Anslyn, C.S.Foote, CHIMICA ORGANICA, Edises

• J. McMurry, CHIMICA ORGANICA,Piccin

• P.Y.Bruice, CHIMICA ORGANICA, Edises

Teaching methods

This course is organized in two teaching units (I and II semester, of the II year). The first teaching unit consists of lectures followed by in-class practices on the applications of the main concepts. Lessons in the first semester are characterized by a methodological approach and are focused on these three topics: chemistry of aromatic compounds, chemistry of carbonyl compounds, carboxylic acids and their derivatives with emphasis in reactions leading to the formation of carbon-carbon bonds, rearrangements. Lessons of the second semester are characterized by a descriptive approach of the sterochemical features of organic molecules and offer a prospect on the most important classes of organic natural products.

Assessment methods

The course 69080 - CHIMICA ORGANICA 2 together with the course 69081 - LABORATORIO DI CHIMICA ORGANICA form the integrated course of CHIMICA ORGANICA 2 CON LABORATORIO (C.I.).

The final exam is designed to assess student knowledge and skills in fundamental organic chemistry and consists of a written 2-hours long test (no handouts or books are allowed) followed by an oral exam. The written test consists of 10 items, 5 relative to the 69080 course and 5 relative to the 69081 course.

Each question has associated a maximum score of 3. Only the students who get a written test evaluation no lower than 18 can take the oral test.

The oral exam will consist of two questions, one per teaching unit. The oral exam lasts about 30 minutes. To get the top score the student must posses a good scientific language, readiness in dealing with the question, and provide adequate answers.

The student's final score is calculated as the arithmetic average of his/her written and oral test scores.

Teaching tools

Multimedia supported lectures.

Links to further information

https://www.unibo.it/sitoweb/claudio.trombini/didattica/programma/2019/322472

Office hours

See the website of Claudio Trombini