METHODS OF CHARACTERIZATION OF ORGANIC MOLECULES

The course fits perfectly into the Chemistry and Sustainable Technologies degree program as it provides the student with important information for the interpretation of the structure of not only organic molecules through the full understanding of analytical techniques such as Nuclear Magnetic Resonance, the ionization for the determination of the mass spectrum, infrared and UV-VIS spectroscopy. Most of these investigation techniques are commonly used in many chemical analysis laboratories, so the course is of great interest to students and particularly useful for their training.

The expected learning outcomes can be divided into the following specific aspects:
1. Knowledge and understanding: i) know the different types of analytical technique (UV-VIS, IR, NMR, mass spectrometry) applied to the structural determination in organic chemistry, in particular know the relationship between spectrum and molecular structure using the different analytical techniques. It is also important for the student to know how to relate these techniques in order to create a method of structural investigation based on a multi-analytical approach.
2. Ability to apply knowledge and understanding: i) know and have learned the instrumental techniques of investigation addressed in the course of the laboratory, ii) know how to relate the information that can be drawn from the different analytical techniques, for example recognition of functional groups to the IR, investigation of the fragments to the mass, assignment of isomers to the NMR; ii) relate the spectroscopic properties of the molecules with their chemical nature, for example acidity of hydrogen atoms and chemical shift to NMR, presence of IR absorption and molecular symmetry.
3. Ability to judge: i) the ability to identify on the basis of partial information which further technique allows to fully solve the molecular structure of an unknown sample, to predict what kind of signal can be expected based on a series of structural hypotheses.
4. Communicative skills: To know how to communicate constructively with the teacher, always maintaining a high level of attention and chemical understanding, using the correct terminology and nomenclature, in a way that is as synthetic as possible, with sufficient expositive security.
5. Learning skills: Knowing how to integrate the didactic material provided by the teacher with clear and concise personal notes.

In order to have a full understanding of the course it is appropriate that the student has acquired the prerequisites of the training objectives in particular of the basic courses of Organic Chemistry since it is highly desirable that the student knows the reactivity and properties of the functional groups. Similarly, it is recommended that the student has acquired the prerequisites of General Chemistry course and the structure and inorganic reactivity of complexes

The course covers a series of analytical techniques applied to the structural determination of organic molecules that allow the recognition of functional groups, mass and fragments of the molecule, symmetry and complete determination both configurational and in some cases also the major conformers. Below is reported the details of the course:
Infrared spectroscopy
introduction to infrared spectroscopy, vibrational model of the binding associated to a spring, intensity of the signals, spectra expressed in wave numbers and transmittance, shape of the absorption bands, relationship between symmetry and IR resonances, resonance tracking of different functional groups , exercises in the classroom.
UV-VIS spectroscopy
Interaction of electromagnetic radiation and molecules, relationship between maximum absorption and molecular conjugation, absorption and color, examples of chromophores and exercises in the classroom.
Mass Spectrometry
Introduction to mass spectrometry, notes on different types of instrumentation and field of application, ionization through electronic impact or chemical ionization (electrospray), application of combined techniques of GC-MS and HPLC-MS analysis, isotopes and isotopic cluster; molecular ion and base peak; fragmentations typical of the different functional groups, loss of a neutral fragment or of a radical, fragmentation reactions characteristic of the main classes of organic compounds. Discussion of examples of mass spectra and exercises in the classroom.
Nuclear Magnetic Resonance Spectroscopy
Introduction to NMR spectrometry, effect of magnetic field on nuclei, nuclear spin and giromagnetic ratio, resonance frequency, chemical around, presence of stereocentres in the molecule, enantiotopic and diastereotopic protons, chemical and magnetic equivalence, definition of chemical shift, relation between substitution- electronegativity and chemical shift, anisotropy of the magnetic field for systems containing double and triple bonds and aromatics, signal integration and relaxation, scalar coupling between identical nuclei and between different nuclei, multiplicity of signals, coupling constants, spin systems to more than two nuclei. Introduction to the dynamic NMR, chemical exchange and effect in the NMR spectrum, slow and fast exchange on the NMR time scale, Discussion of examples of 1H NMR spectra and exercises in the classroom. NMR of 13C, 31P, 19F, and other heteronuclei, some with broadband proton decoupling, Overhauser effect, examples of molecules containing such nuclei.

Introduction to the two-dimensional spectra, COSY and TOCSY for identification of spin systems, HSQC, HMBC for the correct assignment between H and C in the molecular structure. Dipolar interpolation through space and NOESY spectra for the determination of the conformation in solution, selection between NOESY and ROESY spectra as a function of molecular weight. Molecular diffusion, relationship between size and diffusion and DOSY spectra, relation between molecular weight and diffusion.
Examples of complete characterization at the NMR discussed in the classroom. Mono- and two-dimensional NMR spectra of a series of compounds with increasing complexity will be analyzed, including also polycyclic natural substances containing several stereogenic centers.

Application to the determination of unknown compounds
Examples of determinations of structures of unknown compounds will be illustrated starting from the raw formula, the mass spectra, IR, UV-Vis, proton NMR and even two-dimensional heteronuclei.

High Resolution NMR Techniques in Organic Chemistry
Timothy D. W. Claridge, Tetrahedron Organic Chemistry Volume 27, Elsevier
Slides of the lessons available on the Moodle platform

The written test (90 minutes) will consist in the identification of the structure of a simple organic molecule through the combined analysis of IR, MS spectra, 1H NMR and 13C NMR. The student will pass the written exam gaining a minimum score of 18/30., this will allow the access to the oral exam.
During the oral exam the student will be asked questions about all the topics of the course asking more details about examples of spectra that will be submitted to the student for analysis. It is essential that the student responds correctly, with appropriate terminology to the questions demonstrating to know all the topics of the course, to know deeply the different fields of application, the limits and complementarities with other techniques of structural determination (see results of expected learning). The final mark will be the average of the written and oral exams.

The course is organized in lectures (2 academic hours each) in the classroom with the aid of projector and powepoint slides that will be provided from time to time to the students on the moodle platform.
At the beginning of the first day of laboratory will be reminded i) some rules of behavior to be kept in the room and ii) the importance of the use of personal protective equipment and the proper use of chemicals.
In order to stimulate the attention of the students the teacher periodically organizes before the end of the lesson the short (5-10 min) tests that students will follow directly anonymously on their electronic devices (smartphone, tablet, etc.) exploiting the potential of the Socrative platform (https://www.socrative.com/ ). In this way the teacher will be able to view the learning outcomes during the lessons at the end of the lesson in order to be able to take the next lesson to take up some concepts that may be less easily absorbed by the students.
On the University's "moodle" platform there are pdf files related to slides of the presentations projected during the lessons. From the Socrative platform, students will be able to keep track of their tests (not relevant for the final exam as anonymous) and will be encouraged to interact with the teacher in order to ensure their maximum understanding of the course.

Italian

The teacher is available for discussion with the students on the topics of the course, Please, get in contact by email: alesca@unive.it
Accessibility, Disability and Inclusion
Accommodation and support services for students with disabilities and students with specific learning impairments:
Ca’ Foscari abides by Italian Law (Law 17/1999; Law 170/2010) regarding support
services and accommodation available to students with disabilities. This includes students with mobility, visual, hearing and other disabilities (Law 17/1999), and specific learning impairments (Law 170/2010). In the case of disability or impairment that requires accommodations (i.e., alternate testing, readers, note takers or interpreters) please contact the Disability and Accessibility Offices in Student Services: disabilita@unive.it

written and oral