2D NMR experiments can provide an abundance of information for the structural elucidation of chemical compounds. An older example of a 2D experiment is the heteronuclear correlation (HETCOR) sequence. In this experiment, two different nuclei (usually 13C and1H) are correlated through single bond spin-spin coupling, revealing which proton and carbon groups are bonded to each other.Read More
In my opinion, one of the most helpful papersin the field of NMR spectroscopy in Organic Chemistry consists of ‘just’ two tables. In these, the chemical shifts (1Hand 13C) of as many as forty-two common impurities in twelve different deuterated solvents are listed. This is gold! Why? We know, that the signals of one and the same compound can show a rather high discrepancy in its chemical shifts in different solvents. But did you also know, that there is a concept called Aromatic Solvent Induced Shifts (ASIS), which benefits from this fact?Read More
2D NMR experiments provide chemists with evidence to clarify and confirm resonance assignment. Nowadays every organic chemist uses these experiments called COSY, HMBC and HSQC as routine analytics. Basically, with 2D experiments you correlate some kind of information between two 1D spectra. If we correlate two 1D spectra of the same nucleus we are dealing with homonuclear 2D NMR experiments. The most famous representative of this group is the COSY experiment (find theory here and application here).Read More
For many years tetraethyl lead was used as the principal fuel additive to enhance the octane rating of gasoline. In the mid-1970s the use of this substance was reduced because of the environmental hazards of lead and because it poisons catalytic converters. Nowadays, the main application of lead metal and lead oxide is in lead-acid batteries. In this application the cathode of the cell consists of lead dioxide packed on a metal grid and the anode is composed of lead metal. The electrochemical reaction is shown in the following equation:Read More
Since it was discovered, the typical trend in NMR Spectroscopy has been towards higher field, evidenced by the rapid replacement of permanent magnets with supercons. Why? Well, NMR Spectroscopy, of course, is one of the most information rich molecular spectroscopic techniques available, providing information of the type of nuclei, the number of those nuclei and even how they’re connected. As you move to higher field you can immediately observe two things: 1) it’s easier to extract the aforementioned information because the resolution is better (i.e., more Hz/ppm dispersion) given the more favourable dispersion and 2) the data has inherently higher signal-to-noise ratio.