1D NMR Archives - Page 2 of 16

Logic Puzzle #34: Too Much or Too Little, Where is the Happy Middle? … Solution

Arvin Moser Aug 30, 2012

A good approach is to check and compare your experimental data before and after processing to ensure no information is lost. The 1H NMR spectrum below shows two signals at 7.34 and 7.37 ppm. At 0.2 Hz line broadening (LB), the spectrum (bottom) shows two signals as two singlets. With no line broadening, the spectrum...

Logic Puzzle #34: Too Much or Too Little? Where is the Happy Middle?

Arvin Moser Aug 3, 2012

Post data processing can both be a good thing or a bad thing. With any experimental data, too much processing can affect some critical pieces of information. A 1H NMR spectrum was collected for an unknown compound. An exponential function was applied to the data to help improve the signal-to-noise. A line broadening of 0.0...

Logic Puzzle #32: One Real, One Impurity. Which is Which? … Solution

Arvin Moser Jun 29, 2012

A subtle clue can guide an elucidator to choose one scenario over another. Given the 13C NMR spectrum below, it is apparent that either the C at 147 ppm or the CH3 at 29 ppm is an impurity based on the limit of the carbon count. Since both carbons lack any 1H-13C HMBC correlations, a...

Logic Puzzle #32: One Real, One Impurity. Which is Which?

Arvin Moser Jun 22, 2012

Given 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 carbon count is identified at 18 in total. The 13C NMR spectrum below indicates 19 carbon atoms. There are two 13C signals,...

NMR in the Movies? How to Secure a Date with Minnie Driver

Ryan Sasaki Jun 15, 2012

I was flying home from Europe yesterday and was watching the Oscar award-winning movie “Good Will Hunting” starring Matt Damon, Robin Williams, Ben Affleck, and Minnie Driver: One thing I missed the first time I saw the movie, was a moment where Matt Damon’s character shows up at Minnie Driver’s dorm room to ask her...

What is Bosutinib? A Case for CASE

Ryan Sasaki Jun 7, 2012

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...

The Bosutinib Isomer- A Case for NMR ASV?

Ryan Sasaki Jun 4, 2012

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...

Bosutinib: A Case of What Could Have Been?

Ryan Sasaki May 29, 2012

For many years I have been looking for a high profile public case that represents a good example of why an automated NMR structure verification system can help prevent bad things from happening. We all know these types of examples exist, but they don’t generally become public knowledge. Yes, I’ve blogged about this topic many...

Logic Puzzle #30: Unknown Coupling Pattern … Solution

Arvin Moser May 29, 2012

Coupling patterns that overlap can be deceptively simple. There are two possible coupling patterns for the CH2 signal at 3.39 ppm (top spectrum): a singlet or two ‘doublets’ (AB spin system) tilted towards each other. The bottom spectrum shows an example of two ‘doublets’ where the outer signals at 3.34 and 3.43 ppm are barely...

Logic Puzzle #30: Unknown Coupling Pattern

Arvin Moser May 7, 2012

Coupling patterns can be deceptively simple. For an unknown compound, the expanded region of a 1H NMR spectrum below shows a signal at 3.39 ppm for a CH2 group. Is the coupling pattern for this two spin system a ‘true’ first-order singlet?

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