69074 - Organic Chemistry I

Course Unit Page

SDGs

This teaching activity contributes to the achievement of the Sustainable Development Goals of the UN 2030 Agenda.

Good health and well-being Quality education Industry, innovation and infrastructure Responsible consumption and production

Academic Year 2021/2022

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.

Contents:

Introduction. The relevance and the limits of Organic Chemistry. Reminding about the chemical bond. Bonding and anti-bonding molecular orbitals. Resonance. Electronegativity, bond polarity and molecular dipoles.

Organic functional groups and families. 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.

Structure and properties of alkanes and cycloalkanes. Molecular geometries. Bond in hydrides of B, C, N, O, F. 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.

Structure and properties of alkenes and cycloalkenes, dienes and polyenes, alkynes. The C=C pi bond. Structure and nomenclature of alkenes. Physical properties of alkenes. E / Z Isomerism. 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. The C-C triple bond and the structure of alkynes. Nomenclature and physical properties of alkynes.

Structure and properties of organic compounds containing heteroatoms. The C-X sigma bond and the structure of haloalkanes. Nomenclature and physical properties of haloalkanes. Polyfluorinated compounds. The C-O and C-S sigma bonds; structure of alcohols, tiols, ethers, sufides. Nomenclature of alcohols. The hydrogen bond. Physical properties of alcohols. Nomenclature and physical properties of ethers. Solvents in organic chemistry. The C-N sigma bond and the structure of amines. Nomenclature and physical properties of amines.

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

Reactivity in organic chemistry. Reminders 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. The concept of "functionality level". Broensted acids and bases. Lewis acids and bases. Reaction mechanisms and their representation.

Reactivity of alkanes. Combustion, energetic use, greenhouse effect. Halogenation of alkanes: mechanism and selectivity. Stability of radicals and hyperconjugation. Reactivity / selectivity principle (Hammond postulate). Allylic halogenation Hint to oxidation of alkanes and problems of atmospheric pollution and stratospheric ozone depletion.

Nucleophilic substitution and beta-elimination. 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. Stability of carbocations. Stereochemistry of nucleophilic substitutions. E2 and E1 eliminations. Stability of alkenes and regioselectivity of elimination reaction

Reactivity of alkenes and conjugated dienes. Electrophilic addition reaction to the C=C double bond: mechanism, regiochemistry, stability of carbocations, resonant cabocations, carbocation's trasposition. Addition of hydrogen halides. Acid-catalyzed addition of water and alcohols; structure of oxonium ions. Addition of halogens. Formation of halohydrines. 1,2- and 1,4-addition to conjugated dienes. Allilic resonance. Kinetic vs. thermodynamic control. Hydroboration of alkenes and oxidation of boranes. Heterogeneous catalytic hydrogenation of alkenes. Radicalic additions. Radicalic addition of HBr. Oxidations of alkenes. Epoxidation and di-hydroxylation; mechanism; stereochemical implications. Ozonolysis: mechanism and conversion of ozonides.

Reactivity of alkynes. 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. Hydroboration of alkynes; protonolysis and oxidation of alkenylboranes. Acidity of the various types of C-H bonds. Alkynide ions and their reactivity.

Reactivity of alcohols and tiols. Acidity and basicity of alcohols and tiols. Alkoxides and their reactivity. Nucleophilic substitutions on alcohols. Various conversions of alcohols int haloalkanes. Formation of sufonates and nucleophilic substitution. Oxidation of alcohols and diols. The problem of toxicity of chemical reagents and introduction to Green Chemistry concepts. Oxidation of tiols.

Reactivity of ethers, epoxides and sulfides. 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. Oxidation of sulfides. Sulfonium ions.

Reactivity of amines. Basicity of amines. Nucleophilicity of amines: alkylation with organohalides and epoxides. Quaternary ammonium salts. Hofmann and Cope eliminations. Synthesis of amins via azides.

Structure and properties of compounds containing multiple C-O and C-N bonds. The C=O pi bond and structure of the carbonyl group. Nomenclature and physical properties of aldehydes and ketones. The C=N pi bond and structure of imines. Structure of the acyl functional group. Nomenclature and physical properties of carboxylic acids, carboxylates, acyl halides, anhydrides, esters, thioesters, amides. The C-N triple bond, structure and properties of nitriles.

Reactivity of aldehydes, ketones, and imines. The general reactivity of carbonyl compounds. Mechanism of nucleophilic addition reaction to the carbonyl. Basicity of the carbonyl group and acid catalysis. Structure and formation of organometallic compounds. Addition of organometallic compounds to C=O and C=N bonds. Addition of hydrides and hydroboration. Catalytic hydrogenation. Addition of weak nucleophiles: water, alcohols, amines. Formation of acetals. Synthesis of imines. Reduction of imines and reductive amination. Formation of enamines, hydrazones and oximes. Oxidation of aldehydes. Acidity of C-H bonds of aldehydes and ketones. Enolate ions. Keto-enol tautomerism.

Reactivity of acylic compounds and nitriles.  Acidity of carboxylic acids. General aspects of the mechanism of nucleophilic acylic 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. Transesterification. Aminolysis of esters. Amination of carboxylic acids. Acidic and basic hydrolysis of amides. Synthesis of nitriles. 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 exam

 The exam consists of a written test made of 10 questions, partly open answers and partly multiple choice. Students that obtain a score of 15/30 or higher will be eventually 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 second one for 1/4.
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 synthetic strategies, the reactivity, and structure of organic molecules.

Teaching tools

Videoprojection.

Virtual molecular models.

Office hours

See the website of Emilio Tagliavini