69074 - Organic Chemistry I

Learning outcomes

At the end of the class the student has a basic knowledge of the different classes of organic compounds and of the mechanism of the most important reactions. He will be able to solve problems concerning the transformation of simple organic molecules.

Course contents

Pre-requisites: the student should have a good knowledge of the laws and fundamental principles of general chemistry, such as the atomic structure, the nature of the chemical bond, the chemical equilibrium, basic of chemical kinetics and the concepts of acidity and basicity.

Introduction. The relevance and the limits of Organic Chemistry. Remindings of the chemical bond. Binding and anti-binding molecular orbitals. Resonance. Electronegativity, bond polarity and molecular dipoles.

Organic functional groups. Hybrid orbitals and molecular geometries. Functional groups in organic chemistry. The concepts of molecular skeleton and families of organic compounds. The language of organic chemistry.

Reactivity in organic chemistry. Remindings of the concepts of kinetics and thermodynamics of chemical reactions. The Arrhenius law. Intermediates and transition states. Meaning of the activation energy and the concept of catalysis.
Elementary reaction mechanisms. Cleavage and formation of chemical bonds through mono- or bi-electronic processes. Nucleophiles, electrophiles, radicals. Types of reactions: substitutions, additions, eliminations, rearrangements. Oxidations and reductions in organic chemistry. Broensted acids and bases. Lewis acids and bases. Reaction mechanisms and their representation. 

Alkanes and cycloalkanes. C-H and C-C sigma bonds and the structure of alkanes. The concept of isomerism . Nomenclature of the alkanes. Cycloalkanes. Physical properties of alkanes. Origin and importance of alkanes. Conformations of linear alkanes. Structure and conformation of cycloalkanes with 3, 4, 5 and 6 terms. Chair and boat conformations of cyclohexane: axial and equatorial bonds. Substituted cyclohexanes . Cis / trans isomerism in cyclic compounds.

Reactivity of alkanes. Combustion, energetic use, greenhouse effect. Halogenation  of alkanes : mechanism and selectivity. Radical stability and hyperconjugation. Reactivity / selectivity principle (Hammond postulate). Hint to oxidation of alkanes and problems of atmospheric pollution.

Stereochemistry. Chirality of molecules and enantiomerism. Representation of chiral molecules. The C.I.P. system Enantiomery and optical rotation. Racemic mixtures. Compounds with one or more stereocenters. Diastereoisomerism and meso forms. Relevance of chirality.

Haloalkanes. The C-X sigma bond and the structure of haloalkanes. Nomenclature and physical properties. Alkylic nucleophilic substitution. SN2 and SN1 mechanisms. Examples of nucleophiles. Leaving groups other than halides (sulfonates, sulphates, phosphates). Effect of substrate structure and reaction conditions. Stereochemistry of nucleophilic substitutions. E2 and E1 eliminations. Formation of organometallic compounds: oxidative addition. Organofluorinated compounds. Hint to the effect of depletion of stratospheric ozone.

Alkenes. The C=C pi bond. Structure and nomencalture of alkenes. Physical properties. E / Z Isomersm . Electrophilic addition reaction to the C=C double bond: mechanism, regiochemistry, stability of carbocations , resonant cabocations. Addition of halogenidric acids. Acid-catalyzed addition of water and  alcohols; structure of oxonium ions. Addition of halogens . Hydroboration of alkenes and oxidation of boranes. Heterogeneous catalytic hydrogenation of alkenes and mention to homogeneous catalysis. Radicalic additions. Radicalic addition of HBr. Radical polymerization of alkenes. Outline of the main alkene polymers. Oxidation of alkenes. Epoxidation and di-hydroxylation; mechanism; stereochemical implications. Ozonolysis: mechanism and conversion of ozonides.

Dienes and polyenes. Types of polyenes (isolated, conjugated, cumulated) and nomenclature. Polyene stability. The structure of allenes. Electronic structure of conjugated dienes: HOMO and LUMO. Interaction of alkenes with electromagnetic radiation,mention of the mechanism of retinal vision. Addition 1,2 and 1,4 to conjugated dienes. Allilic resonance. Kinetic vs. thermodynamic control.

Alkynes. The C-C triple bond and the structure of alkynes. Nomenclature and physical properties. Electrophilic additions to alkynes: single and double addition of HX, alcohols, halogens. Addition of water to alkynes and keto-enol tautomerism. Hydrogenation and semihydrogenation of alkynes. Reduction with solvated electrons. Acidity of the various types of C-H bonds. Alkynide ions and their reactivity. Industrial importance of acetylene. 

Alcohols. The C-O sigma bond and the structure of alcohols and ethers. Nomenclature. The hydrogen bond. Physical properties. Acidity and basicity of alcohols. Alkoxides and their reactivity. Nucleophilic substitutions on alcohols. Oxidation of alcohols.

Ethers. Nomenclature. Physical properties. Solvents in organic chemistry. Williamson synthesis of ethers and its limitations. Acid-catalyzed synthesis of ethers. Nucleophilic substitutions on ethers. Cyclic ethers. Epoxides. Nucleophilic additions to epoxides under SN1 or SN2 conditions.

Carbonyl compounds. The C=O pi bond and the structure of the carbonyl group. Nomenclature of aldehydes and ketones and physical properties. The general reactivity of carbonyl compounds. Mechanism of nucleophilic addition reaction to the carbonyl. Basicity of the carbonyl group and acid catalysis. Addition of organometallic compounds. Addition of hydrides and hydroboration. Catalytic hydrogenation. Addition of weak nucleophiles: water, alcohols, amines. Acetals and ketals. Oxidation of aldehydes. Acidity of aldehydes and ketones. Enolate ions. Keto-enol tautomerism. Aldol reactions under basic catalysis . Cross-aldol reactions. Hints to the use of strong bases. Elimination from aldols and ketols. Enals and enones.

Amines. The C-N sigma and C=N pi bonds and the structure of amines and imines. Nomenclature and physical properties. Basicity of amines. Nucleophilicity of amines: alkylation with organohalides and epoxides. Quaternary ammonium salts. Synthesis of imines and reductive amination. Reactivity of imines, immonium ions, enamines. Relevance of amines as natural and bioactive substances.

Carboxylic acids and acyl compounds. Structure of the acyl functional group. Carboxylic acids, carboxylates, acyl halides, anhydrides, esters, thioesters, amides. Nomenclature and physical properties. Acidity of carboxylic acids. General aspects of the mechanism of nucleophilic acyl substitution and reactivity/stability scale. Reactions of acyl halides and anhydrides. Conversion of carboxylic acids to acyl chlorides. Acid esterification and acidic hydrolysis of esters. Basic hydrolysis of esters. Reactivity of thioesters. Transamination. Aminolysis of esters. Amination of carboxylic acids. Acidic and basic hydrolysis of amides. Nitriles. Nomenclature and properties. Nitrile synthesis. Acidic and basic hydrolysis of nitriles. Reduction of carboxylic acids, esters, amides, nitriles. Addition of organometallic compounds to esters and nitriles. 

Readings/Bibliography

 Any Organic Chemistry textbook at university level is usually valid. Here is some suggestions

1. Peter C Vollhardt Neil E Schore, "Chimica Organica", Zanichelli, Bologna. 2016

2. W. H. Brown, C. S. Foote, B. L. Iverson, E. V. Anslyn "Chimica Organica" EdiSES, Napoli.

3. J.McMURRY "Chimica Organica" Ed. Piccin, Padova.(5)

4. T.W.G.SOLOMON "Chimica Organica" Ed. Zanichelli, Bologna.

5. P.Y. Bruice “Chimica Organica” EdiSES, Napoli.

6. R.J.FESSENDEN, J.S.FESSENDEN "Chimica Organica" Ed. Piccin, Padova.

Teaching methods

Lectures and videoprojection.

Exercises.

Discussion.

Assessment methods

Written and oral

 The exam consists of a written test of 10-12 questions, partly open open answers and partly multiple choice. Students that obtain a score of 15/30 or higher will be finally interviewed with a single question. The final mark will be the average of the scores of the written and oral parts, the first one accounting for 3/4.
The exam aims to verify the achievement of the following learining objectives: (i) familiarity with the logic, concepts and tools of organic chemistry; (ii) ability to write, recognize, attribute the name and predict the properties and the reactivity of organic molecules; (iii) describe rigorously and clearly the mechanisms of organic reactions; (iv) ability to use the above concepts to solve simple problems concerning the reactivity and structure of organic molecules.

Teaching tools

Videoprojection.

Real and virtual molecular models.

Office hours

See the website of Emilio Tagliavini