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The wealth of analytical information that is generated every day in R&D organizations can provide rich insights, even months after the initial acquisition of data. With this increase in data, however, comes a significant challenge to combine, organize, access, visualize, and mine these informational repositories. In addition to the challenges of the growing volume and...

I got some great comments from Tony and Gary on the “Dealing with a Mixture…” post that I decided to do a follow-up post. http://acdlabs.typepad.com/elucidation/2008/02/dealing-with-a.html In my lab days, I would routinely workup a newly acquired 1H NMR for an unknown sample prior to acquiring a 2D NMR dataset. One of my goals was to examine...

Rings plus Double Bonds Equivalent (RDBE) (also known as the degree/element of unsaturation or index of hydrogen deficiency) can be determined from a Molecular Formula (MF). The calculation provides insight into the number of rings and/or double bonds and/or triple bonds to expect from an unknown structure. RDBE = (# of C) + 1 –...

In light of the posting by Oliver Fiehn’s group (http://fiehnlab.ucdavis.edu/projects/Seven_Golden_Rules/Ring-Double-Bonds/), I’ve decided to blog some compounds I’ve encountered in the lab. Using the 2nd formula from the previous blog (http://acdlabs.typepad.com/elucidation/2008/03/rings-double-bo.html), for some cases the RDBE calculation will work if the correct atom valence is known. Note: the nitrochloroform compound can be drawn more than one...

The underlying essence of a structure elucidation process is to structurally distinguish an unknown from a set of possible isomers. This is evident by the number of possible isomers for a given molecular formula. The chart below divides isomers into two groups: Structural/Constitutional/Regio and Stereo/Spatial isomers. Wikipedia links are included for further reading into the...

The approach behind solving a structure elucidation problem is very similar to attempting a math problem or working on a jigsaw puzzle. This similar mental framework shares a basis, but not limited to, on understanding the basic rules that define the problem, and in some cases the creativity and flexibility to redefine the problem. When...

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....

TLC (Thin Layer Chromatography) offers a simple approach to identifying a solvent(s) for separating out a mixture, monitoring a reaction to completion, etc. Furthermore, the TLC plates can be stained to identify the presence or absence of various functional groups such as amines, ketones, etc. This qualitative experiment does offer various drawbacks. The process of...

Coupling information is very useful in locating the position of an atom in relation to other atoms. This puzzle covers one such example. For an unknown compound1, a di-substituted phenyl ring with a fluorine substituent was deciphered. The 13C NMR spectrum below shows two 13C signals split due to 19F-13C coupling. Which carbon, chemical shift...