OVERVIEW

The 5-credits course for Chemistry and Chemical Technologies (L-27) deals with the great groups of natural organic compounds (carbohydrates, proteins, lipids, alkaloids) and with the main spectroscopic methods (IR, 1H NMR) to identify the molecular structure of organic compounds.

The 4-credits course for Materials Science (L-30), Methodologies for Conservation. Cultural Heritage (LM-11) and Environmental and Natural Sciences (L-32), deals only with the main spectroscopic methods (IR, 1H NMR).

LEARNING OUTCOMES

Identifying molecular structures of organic compounds by spectroscopic methods.

AIMS AND LEARNING OUTCOMES

Understanding the molecular structure of carbohydrates, proteins and lipids and the chemical properties of monosaccharides.

Understanding the basic principles of organic spectroscopy.

Identifying the molecular structure of organic compounds on the basis of raw formula, infrared (IR) and proton magnetic resonance (1H NMR) spectra.

Teaching methods

Front lessons with (Power Point) slide projection and use of clickers with interactive software for verifying the
understanding of the fundamental concepts of the lesson.

Solving spectroscopy problems in the classroom.

SYLLABUS/CONTENT

CARBOHYDRATES. Monosaccharides: molecular structure of the main compounds, stereoisomerism, steric series, cyclic forms, mutarotation, reducing sugars, oxidation and reduction reactions, glycosides. Reducing disaccharides: cellobiose, maltose, lactose. Not-reducing disaccharides: sucrose. Polysaccharides: cellulose, starch, glycogen. 

PROTEINS. Amino acids: structure, nomenclature, apolar zwitterionic cationic and anionic forms, isoionic point, electrophoresis. Proteogenic amminoacids: structure, steric series, possible features. Peptides and proteins: primary structure, main kinds of secondary structure (alpha helix or beta-pleated sheet, their rationale and their stabilization), tertiary structure (intrachain interactions, denaturation, fibrous and globular proteins), quaternary structure. Enzymes as catalysts: active sites, key-to-lock interactions, drugs, poisons.

LIPIDS. Hystorical definition. Lipids exhibiting C=C double bonds, or exhibiting alcohol, ketone or carboxylic groups. Glycerides. Importance of the presence of C=C double bonds exhibiting Z configuration in determining the melting points of  fatty acids and glycerides. Waxes. Steroids. Terpenes. 

ALKALOIDS. Molecular structure of the main compounds.

IDENTIFICATION OF MOLECULAR STRUCTURES. The raw formula and the unsaturation index. Electromagnetic radiations. Kinds of molecular energy. When the energy exchange between radiations and molecule takes place. Kinds of molecular spectroscopy. An outline of Visible/Ultraviolet spectrocopy. Coloured compounds. INFRARED (IR) SPECTROSCOPY. The complex molecular vibration and its partial dissection in localized stretching and bending vibrations. The selection rules. The stretching wavenumber as a function of the force constant and the reduced mass. Detailed analysis of the spectral region of functional groups. The fingerprint region. NUCLEAR MAGNETIC RESONANCE (NMR) SPECTROSCOPY: Magnetic properties of the proton. Magnetic and nonmagnetic nuclei. The magnetic energy levels generated by a strong external magnetic field. The resonance frequency as a function of the magnetogyric ratio, the external magnetic field and the shielding factor. The good separation between the resonance frequencies of the various isotopes. The delta scale, the reference signal and the most used deuterated solvents, the low sensitivityof the method. 1H NMR SPECTROSCOPY. Identification of the exceeding (solvent, moisture, impurities) signals. The number of signals (chemically equivalent and nonequivalent nuclei). The relative intensity of signals. The chemical shift (the contributions of near-by electric currents, of the local electron density and of intermolecular associations). Spin-spin splitting and coupling constants (dependence of vicinal coupling constants on torsion angles, bond lengths, ring size and atom electronegativity).An outline of Fourier-Transform (FT) spectrometers.

General strategy to solve spectroscopy problems.

RECOMMENDED READING/BIBLIOGRAPHY

Full didactic support can be found in Aulaweb.

Exam Board

LARA BIANCHI (President)

MASSIMO MACCAGNO

RENATA RIVA (President Substitute)

CINZIA TAVANI (Substitute)

Teaching methods

Front lessons with (Power Point) slide projection and use of clickers with interactive software for verifying the
understanding of the fundamental concepts of the lesson.

Solving spectroscopy problems in the classroom.

Exam description

Written test which consists in identifying two molecular structures of organic compounds based on chemical formula, IR spectroscopy and 1H NMR spectroscopy; it is necessary to identify both structures in order to be admitted to the oral exam.

Oral exam on the large families of natural organic compounds and on the basic principles of various spectroscopic methods.

The written test and the oral exam must be taken in the same session.

Assessment methods

The written exam will evaluate the ability of the student to use theoretical notions to identify the structure of two organic molecules, given the chemical formula and the IR and 1H-NMR spectra.

The oral exam will mainly focus on the topics covered during the lessons and will aim to assess the achievement of the appropriate level of theoretical knowledge. The ability to present the topics clearly and with correct terminology will also be evaluated.

Exam schedule