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ACD/Labs Blog

Arvin Moser
With any experimental data, producing a list of scenarios that are consistent with the data can help guide an elucidator through the problem while ensuring nothing gets overlooked. For an unknown compound, the 1H -13C HMQC spectrum shows a CH group with a correlation at 7.0 and 113.0 ppm. Is the carbon hybridization an sp2 or...

Ryan Sasaki
PKC Pharmaceuticals is working very hard to try and not only remedy the issues that have come out of the Bosutinib issue described in previous posts and in other media outlets, but to also really understand what went wrong, what is out there, and how to clear the air on this issue. I believe they...

Ryan Sasaki
I’ve already described the Bosutinib fiasco in my last entry, and finished with a teaser that we would be back for more commentary on this topic. We plan a series of tests of our algorithms and systems to see if our software could have been used to prevent a situation like this. The main question...

Arvin Moser
Part of the process of interpreting data from 2D NMR spectra is to adjust the intensity threshold in order to differentiate visually the signals from the noise. A certain level of cautious peak picking is needed so not to overlook a weak signal nor confuse a noisy region for a real signal. For an unknown...

Arvin Moser
Spectral data that exhibit weak signals (low S/N) can easily be misinterpreted. A good approach is to check the data against other data to confirm whether the signal is real or an artefact. For an unknown compound, the 1H -13C HSQC spectrum below is shown at two different intensity thresholds. The aromatic protons at 6.97...

Arvin Moser
Given a set of data points, the elucidator aims to conjure up a variety of scenarios that are consistent with the data at hand. This puzzle aims to draw out an unlikely, but worth considering, scenario that needs to be verified. The expanded region for the 1H-13C HSQC-DEPT spectrum presents two scenarios that are consistent...

Arvin Moser
For this puzzle, the objective is to extract structural information from the NMR data. However, the underlying message is to check all possible atomic combinations so that no plausible fragment gets overlooked. For an unknown compound, an expanded region of the 1H-13C HSQC-DEPT spectrum below shows two 1H multiplets and two negatively-phased correlations (blue). The...

Arvin Moser
With each piece understood, a fragment(s) will emerge. From the 1H-13C HSQC spectrum, there are 3 CHn groups where n represents 1, 2 or 3 protons. The proton integrals indicate 2 CHs and 1 CH3 group. The CH3 group is observed as a singlet with 1H and 13C chemical shifts at 3.35 and 56.93 ppm;...

Arvin Moser
Piece by piece, fragment by fragment, an unknown compound is constructed until it is solved. The purpose of this puzzle is to focus on solving a fragment. The 1H-13C HSQC spectrum, shown below, is for an organic three-carbon fragment. The fragment is known to have 2 open sites that connect back to the structure. What...