Spectroscopic methods in organic chemistry

A.Y. 2019/2020
Overall hours
Learning objectives
The course aims at deepening the most significant instrumental methodologies that allow obtaining information on the structural characteristics of organic molecules. The processing of the data thus obtained allows to intervene in the synthesis, development, production and analysis of the organic substances considered.
Expected learning outcomes
Knowledge of the most important spectroscopic technique for the structural identification and characterization of simple and complex organic compounds. Identification and choice of the appropriate techniques for solving complex structural problem.
Course syllabus and organization

Linea LZ

Course currently not available
Lesson period
Second semester
CHIM/06 - ORGANIC CHEMISTRY - University credits: 7
Practicals: 16 hours
Lessons: 48 hours

Linea Unica

Lesson period
Second semester
Course syllabus
GENERAL: electromagnetic spectrum and electromagnetic radiation, electromagnetic radiation characterization, electromagnetic radiation and interactions with matter, spectroscopic techniques.
INFRARED SPECTROSCOPY: fundamental principles, frequency of infrared absorption and chemical structure. Systematic part: hydrocarbons (alcohols, alkenes, alkynes, aromatics), alcohols, ethers, halides, carbonyl compounds, amines. Combined examples. Instrumentation and recording, IR Spectrophotometer and Fourier Transform IR (FT-IR). Evolution and applications of IR spectroscopy.
NUCLEAR MAGNETIC RESONANCE, NMR: general principles, nuclear properties, magnetic field and electromagnetic radiation (radiofrequency).
Proton nuclear resonance: 1H NMR observation in a stationary and rotating reference system, resonance spectrum of an isolated proton and real protons in different intensity magnetic fields, spectral amplitude, chemical displacement intervals and internal reference, chemical displacement in hertz and (ppm).
Examples of non-coupled systems and assessment of the structure's influence on chemical displacement.
Coupled systems: the spectrum of ethyl acetate, multiplicity of signals, general principles.
Coupling with equivalent protons, non-equivalents and mixed systems, describing the multiplicity of signal through the cascade diagrams.
Examples of simple coupled systems: assessment of the structure's influence on chemical displacement and the multiplicity of signals.
Coupling constant and structure: geminal, vicinal and long-range coupling.
Exercise on a collection of proton spectra of simple non-aromatic compounds.
Chemical shift and structure, chemical shift equivalence: random, isochronal protons, homotopic protons, enantiotopic, diasterotopic. Magnetic Equivalence.
Examples: keto-enol equilibria, limited rotation, alicyclic compounds
Practice on a collection of proton spectra of simple aromatic compounds, spin system simulation (cascade diagrams), reading of spin systems (determination of coupling constants and chemical shift).
Protons on heteroatoms: Oxygen, Nitrogen and Sulfur.
Experiments of double resonance with examples.
NOe differential experiments with examples.
Nuclear magnetic resonance of carbon-13: general principles, relative and absolute sensitivity of an NMR experiment, chemical shifts, proton-proton and proton-carbon coupling, examples of simple aromatic and non-aromatic compounds, 13C-NMR spectra recorded with the APT and DEPT techniques.
Instrumentation: subtraction of reference frequency, analog-to-digital converter (ADC), ADC characteristics (Acquisition time (At), sampling rate, digital resolution (Rd)), radio frequency pulse (PW, pulse width), impulse duration, and spectral amplitude.
Acquisition sequences: 1H-NMR, 1H-NMR with selective decoupling, 1H-NMR nOe-diff, 13C NMR with 1H / 13C coupling, 13C-NMR decoupled 1H / 13C, 13C NMR APT, 13C NMR DEPT.
Nuclear magnetic resonance of other nuclei: general principles, nuclear magnetic resonance of the 15N. Reading spectra coupled and decoupled from the proton. 19F and 31P nuclear magnetic resonance imaging. Reading spectra coupled and decoupled from proton, reading proton spectra and carbon containing fluorine and phosphorus compounds.
Two-dimensional magnetic resonance spectroscopy (2D). COrrelation Spectroscopy COSY, HSQC; HMBC, NOESY and TOCSY.
Examples combined with 2D techniques.
MASS SPECTROMETRY: General principles and instrumentation. Sources (EI, CI, FAB, MALDI, ESI APCI), analyzers (magnetic, quadrupole, ion trap), detectors. Analysis of a mass spectrum: molecular ion, fragment ions, general classification of fragmentation reactions. Systematic part: fragmentation reactions of the main classes of organic compounds with exercises.
Final Exercises on Structural Determination of Organic Compounds with Combined Techniques.
Prerequisites for admission
Prerequisites necessary for attending the course are a good knowledge of physics and organic chemistry. In particular, adequate knowledge of the concepts of atomic structure, reactivity of functional groups in organic structures and stereochemistry is required.
Teaching methods
Frontal lessons and guided and non-guided classroom exercises.
Teaching Resources
Identificazione spettrometrica di composti organici Terza edizione
R.M. Silverstein, F.X. Webster
Casa Editrice Ambrosiana
Structure determination of organic compounds, practical exercises
E. Rossi, D. Nava, G. Abbiati, G. Celentano, S. Pandini
Casa Editrice Edises
Assessment methods and Criteria
Exam Mode: written in two parts a theoretical and a practical one. Theoretical part with questions on topics discussed in frontal lessons. Practical part: assigning an unknown structure based on IR, MS and NMR spectra and / or confirming a known structure based on data spectra, mass fragmentation exercises, and reading of bidimensional NMR spectra.
The student's ability to correctly use the experimental data obtained using the different spectroscopic techniques studied during the course to reach the univocal determination of the structure of an organic molecule will be assessed.
The ability to use scientifically appropriate language and the ability to organize the display of data and its use will also be assessed.
CHIM/06 - ORGANIC CHEMISTRY - University credits: 7
Practicals: 16 hours
Lessons: 48 hours
Professor: Rossi Elisabetta