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Symmetric Helical Synthesis Product This month’s problem is again a bit different from the others. It comes from the Department of Chemistry, University of Bath, UK. John Lowe had been trying to challenge Structure Elucidator and asked his colleagues at the Department for interesting problems. David Carbery gave him two synthetic samples, A and B,...

This article discusses how using the mean of the LRI values predicted by RapidMiner and ACD/ChromGenius, in combination with accurate mass data, could enhance the confidence level for compound identification from the analysis of complex matrixes; the goal being to reduce the list of putative candidates to a reasonable number that can be obtained and...

InChIKey is a 27-character compacted (hashed) version of InChI which is intended for Internet and database searching/indexing and is based on an SHA-256 hash of the InChI character string. The first block of InChIKey encodes molecular skeleton while the second block represents various kinds of isomerism (stereo, tautomeric, etc.). InChIKey is designed to be a...

A biased elucidation is an elucidation where the chemist makes certain assumptions about the data at hand based on a previous experience(s) and not deviating from it. Depending on the elucidation, it can be a good thing or a very bad thing. As a good thing, it can speed up the time spent on an...

Here is a lesson I learnt over time while working on small molecules—my Elucidation Evolution. Thinking back to when I started doing elucidations of unknowns, my mindset was to collect loads of data (NMR, MS, IR, etc.) whether I needed it or not. Initially inexperienced, I was extracting bits and pieces of information from various...

When trying to elucidate an unknown structure using 2D NMR information, an elucidator gains an advantage by analyzing all of the NMR data as a whole rather than as individual pieces. Although complicated at first, this different perspective at viewing the NMR data can facilitate the elucidation process. The following list are a few advantages...

In addition to using chemical shift information to ascertain a carbon’s proton count (i.e. C, CH, CH2 or CH3), 13C NMR experiments can be set up in a variety of ways to assist with this process. The following simulated spectra compare a variety of 13C NMR experiments for aspartame. Please note that there are variations...

When dealing with a structure elucidation problem where little or no previous fragment information exists, the number of possibilities can seem endless. Although typically one envisions a neutral compound for the unknown, ionic compounds, such as salts and zwitterions, are also just as likely and thus can add to the complex nature of an elucidation....

After a long and arduous attempt at an elucidation, it is quite common to be left with more than one candidate structure. In some cases collecting more data is not an option and an exhaustive database/literature search turns up nothing useful, the alternative approach is to synthesize the proposed candidates and then compare the spectral...