Different elements will have different frequencies leading to different chemical shifts ( Table 1). The FID is Fourier transformed to give the peaks of the NMR spectrum. When the radiation is ceased, the nuclei will undergo relaxation and a free inductive decay (FID) is obtained. Irradiation with electromagnetic radiation will cause the low energy state to flip over to the high-energy state. These two states have different energy levels: a low-energy state and a high-energy state. The spins are random and spins in random directions however, by applying an external magnetic field these nuclei will align themselves either with or against the applied magnetic field. Nuclei with an odd mass or atomic number will have a property called spin, making it possible to use NMR to detect elements such as hydrogen ( 1H), carbon ( 13C), and phosphorus ( 31P). The reaction that will be shown is the synthesis of an E-chalcone ( 3) from an aldehyde ( 1) and a ketone ( 2) ( Scheme 1). iii) Identifying the product obtained from a reaction with 1H NMR. The following will be shown: i) preparation of an NMR sample. This video exemplifies how NMR spectroscopy can be used in the everyday work of an organic chemist. Moreover, it is possible to monitor the completion of a reaction by comparing NMR spectra of the starting material to that of the final product. The protons present in a molecule will behave differently depending on its surrounding chemical environment, making it possible to elucidate its structure. One of the most frequently used NMR techniques for an organic chemist is proton ( 1H) NMR. Compared with other commonly encountered techniques for organic chemists - such as thermal analysis and mass spectrometry (MS) - NMR is a non-destructive method that is valuable when recovery of the sample is important. Not only can it provide information about the structure of a molecule but also determine the content and purity of a sample. With the help of NMR, the work in the organic lab has been facilitated tremendously. Nuclear magnetic resonance (NMR) spectroscopy is a vital analysis technique for organic chemists. Henrik Sundén – Chalmers University of Technology

Mestrenova compared spectra