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ACD/Labs Blog

Ryan Sasaki
Great post from Derek Lowe from In the Pipeline the other day talking about the dangers of not quality checking those fine-looking starting compounds for your project. Chemistry happens and yes, mistakes do too. In fact, it appears that Derek has been on a kick as of late referring to personal QC. I Can Has...

Arvin Moser
Like a methoxy group, a t-Butyl group stands out over other 1H resonances. For organic compounds, the 1H resonance for a t-Butyl group generally towers over other 1H resonances because it integrates to ~9 protons (assuming the presence of 1 t-Butyl group and no overlap with other resonances). The basic 1H NMR pattern of the...

Arvin Moser
MS and NMR are complementary tools for structure elucidation. Knowing when to apply which tool can assist an elucidator in solving for an unknown structure quickly and with less frustration. Although the sample data below is for a simple organic structure, it is working through many simple examples that one refines the skills needed for...

Arvin Moser
Although peak crowding can be a nuisance, a monosubstituted benzene fragment can be identified by a 1H NMR. A good marker for a monosubstituted benzene ring, and thus how an elucidator can clue in to its presence for an unknown, is whether the sum of the relative integrals for the aromatic resonances add up to...

Arvin Moser
Typically, structure elucidation via NMR can be ascribed by a stepwise workflow: 1. a sample is prepared for NMR, 2. the NMR instrument is optimized for data collection, 3. NMR data is acquired, 4. the spectral data is processed, 5. the spectral data is searched/compared to an internal database for possible hits or similarities, 6....

Ryan Sasaki
In fact, to borrow a phrase from a colleague, this might be the defacto article on Computer Assisted Structure Elucidation (CASE) for the next decade! This article written by Mikhail Elyashberg, Antony Williams, and Gary Martin spans across two issues of the review journal, Progress in Nuclear Magnetic Resonance Spectroscopy.  This article entitled, entitled, "Computer-Assisted...

Arvin Moser
Methoxy groups have a distinct NMR signature that make them easy to spot in virtually every case. The basic pattern is a singlet integrating to 3 and ranging between 2.4 to 4.4 ppm on a 1H NMR spectrum (assuming no overlap with other resonances). On the 13C end, a 13C resonance is seen between 46...

Arvin Moser
An integral part of an elucidation is to recognize and associate an NMR spectral pattern to a structure or fragment. A challenging elucidation can be simplified by being aware of as many as possible NMR patterns. One example is morpholine; it typically shows a distinct NMR pattern. A portion of the 1H-13C DEPT-HSQC spectrum for...

Ryan Sasaki
I’ve blogged several times about the progress and applications of automated structure verification with the help of ACD/Labs software. There are really two main approaches right now: Combined verification which includes automatically verifying the correspondence between a proposed chemical structure and the 1D 1H and 2D HSQC spectra. I’ve blogged about the publications and applications...

Arvin Moser
Without a set routine to acquire a 19F NMR spectrum for every single sample, an elucidator must resort to routine NMR experiments for clues to the presence or absence of fluorine. For the elucidator who routinely acquires a proton decoupled 13C NMR, the spectrum can provide some clues into the presence of fluorine. Carbons in...