Skip To Content

ACD/Labs Blog

Arvin Moser
With intense solvent signals present on a spectrum, a smaller signal(s) can easily be missed. If 2D NMR data is available, then this extra information can assist in clarifying whether a small signal(s) is obscured by larger signals. On the 1H-13C HMBC below, the correlations for CDCl3/CHCl3 (due to 1J coupling responses and more) are...

Arvin Moser
‘How many signals are present?’ is such a simple question, and yet, it is a fundamental question to an elucidator. Mistaken a signal or overlook one and the elucidator can run the risk of wasting time and effort.   The 13C [1H] NMR spectrum below shows 3 discernible signals that are attributed to the solvent CDCl3. In...

Arvin Moser
When dealing with small sample concentrations of an unknown compound, the NMR region where a large solvent signal appears rarely gets a second look. However, a large NMR signal can easily obscure a small signal. From one elucidator to another, check the solvent signal for any structural signals. In the 13C [1H] NMR spectrum below,...

Arvin Moser
Socrates is known for saying ‘Know thyself’, along the same line, chemists should ‘Know thy instrument’. The example below is one such case. The 13C NMR [1H] spectrum below exhibits 6 signals. If an unknown compound comprises of 7 carbon atoms, then the following scenarios, or combinations thereof, are possible to account for missing or extra...

Arvin Moser
Structure elucidation by NMR involves a deep understanding of various technical aspects behind data acquisition. Being aware of how the instrument works can facilitate the process and reduce the aggravation. For today’s puzzle, an unknown compound is known to comprise of 7 carbon atoms and exhibit the following 13C NMR spectrum with 1H decoupling. How...

Arvin Moser
The goal of this puzzle is to determine how the molecular formulae of the intermediates may assist in reasoning out the final product. In this puzzle, let’s consider the following one-pot synthetic reaction (solvents and additional reactants are not shown). The molecular formula (MF) and the RDBE information are also presented. The chemical reaction illustrates...

Arvin Moser
Part 1 presented a challenge to determine an experiment to distinguish two very similar products from each other, namely 3-methyl-5-(pyridin-2-yloxy)pyridine and 5′-methyl-2H-1,3′-bipyridin-2-one. The products have identical formula weights and the LC/MS and 1H NMR are too similar to draw any conclusion from. The first step is to determine what is different between the two products...

Arvin Moser
Many organic chemists—if not all—check to see if a synthetic reaction is complete via TLC and LC/MS and/or 1H NMR. At the same time, the chemists are using the analytical data to verify that the final product is what they intended on making. In some cases, LC/MS and 1H NMR do not adequately distinguish one potential product...

Arvin Moser
In this final installment of the series on Drug Development, we examine stage 4 and the effort involved in Drug Manufacturing and Process. The 4th stage begins with a large scale production of the new drug, followed by formulation studies and then ending with regulatory reviews of the entire process before the drug can be...

Arvin Moser
The main focus surrounding the Drug Design stage (see diagram in Part 1) is to optimize the hit compound(s) and produce analogues that will increase the activity at the target site. Lead optimization is accomplished through minor modifications of the hit compound. In Drug Design, medicinal chemists aim to build a diverse library of compounds...