69080 - Organic Chemistry II

Academic Year 2017/2018

  • Teaching Mode: Traditional lectures
  • Campus: Bologna
  • Corso: First cycle degree programme (L) in Chemistry and Materials Chemistry (cod. 8006)

Learning outcomes

Al termine del corso, lo studente conosce metodologie fondamentali per la preparazione di molecole organiche aromatiche o alifatiche applicando le nozioni acquisite sulla chimica dei composti aromatici e dei composti carbonilici, carbossilici e dei rispettivi derivati. Lo studente sarà in grado inoltre di analizzare una molecola organica di media complessità per quanto attiene alle sue caratteristiche stereochimiche e alle relazioni struttura-reattività. Conoscerà le più importanti classi di sostanze organiche naturali da un punto di vista descrittivo e sarà inoltre in grado di eseguire semplici trasformazioni su di esse.

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 Teaching Unit (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 Teaching Unit (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.

·        Terpenes, structure and biogenesis.

·        Cationic rearrangements. The squalene route to lanosterol.

·        Fundamental steroids.

Readings/Bibliography

Lessons handouts and presentations are  available to students who then deepen main 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, respectively of the II year). Each teaching unit consists of lectures followed by in-class practices on the applications of the main concepts. The first unit is characterized by a methodological approach and is 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. The second unit is characterized by a descriptive approach of the sterochemical features of organic molecules and offers a prospect on the most important classes of organic natural products.

Assessment methods

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 per teaching unit.

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.

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

Teaching tools

PC, videoprojector

Office hours

See the website of Claudio Trombini