'Hop' off the Diagonal: COSY spectrum of α-humulene

'Hop' off the Diagonal: COSY spectrum of α-humulene

NMR spectroscopy is by far the most useful characterization technique in organic chemistry, especially if you have to elucidate the structure or configuration of your products. Arguably, 2D experiments such as COSY, HSQC, and HMBC have simplified this task tremendously. In this post I wanted to highlight the COSY of α-humulene. 

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What to expect: Chemical Shifts & Coupling Constants in Low-field NMR Spectroscopy

One of the questions that we always get at tradeshows and conferences is how our instrument compares to high-field data. There are significant inherent differences between low-field and high-field instruments, but the most important from a chemistry point of view are sensitivity (S/N) and resonance dispersion (signal separation).

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The NMR tube....for any occasion

The NMR tube....for any occasion

We have recurring interest from industrial customers (e.g., pharma, flavour/fragrances) to acquire spectra using only small amounts of analyte in our benchtop NMR instruments – considerably less than our recommended 0.1 M concentration (link).  Why is our recommended concentration so high?  Well, it’s reflective of the consequences of a low-field instrument.  That is, lower-field results in inherently lower sensitivity and accordingly a decrease in observed signal to noise ratio (S/N).

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The lightest metal with a heavyweight demand: Lithium

The lightest metal with a heavyweight demand: Lithium

Before the early 1950’s lithium was an ingredient found in Seven-up®; however, after concerns by the FDA it was removed from this popular beverage. Interestingly, about the same time it was found that lithium had antipsychotic properties, but it was only approved for human consumption in the 1970’s.[1] Despite being such a simple molecule lithium carbonate is still the most effective drug for the treatment of bipolar affective disorder! We don’t hear this side of the lithium history very often. In recent years this element has become very popular and its demand has increased considerably due to its widespread use in batteries for small electronic devices such as smart phones and laptops.[2]

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A watched pot never boils… how to monitor reactions the easy way!

A watched pot never boils… how to monitor reactions the easy way!

When monitoring reaction progress for determination of reaction kinetic parameters, NMR spectroscopy has increasingly become the method of choice. The ease in which one can calculate the concentration changes of a substrate being consumed or a product being formed over time, directly from peak integration are the reason behind this.

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Life is sweet…maybe too sweet!

Life is sweet…maybe too sweet!

Sugar substitutes are gaining more and more relevance due to the heath problems associated with the consumption of high amounts of sugar. Specifically, excess sugar consumption has been associated with obesity, type II diabetes, cardiovascular disease, certain cancers, and tooth decay. In the United States, it is estimated that the average person consumes more than 126 grams of sugar per day, in Canada around 89 grams per day.

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The Dangers of Making Too Many Assumptions. Electronegativity, Acidity, and Chemical Shift

The Dangers of Making Too Many Assumptions. Electronegativity, Acidity, and Chemical Shift

Last month (which you can see here), we learned about how an acidic proton behaves in a 1H NMR experiment, particularly when it’s surrounded by D2O. For example, when an H+ leaves CH3COOH to join an accommodating D2O molecule, the resulting acetate (H3CCOO–) segment is reasonably comfortable bearing that negative charge. This phenomenon is the reason the solution is “acidic” in the first place. But why is acetate so capable of dealing with this negative electronic charge?

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To Decouple or Not to Decouple, That is the Question. Also….Acids.

To Decouple or Not to Decouple, That is the Question.  Also….Acids.

Acidity is something that you encounter on a daily basis, probably without even realizing it. The tangy taste of an orange (citric acid), that Vitamin C tablet you took this morning (ascorbic acid), those terrible jeans from the 80’s that you still wear (acid wash). My favourite acid is acetic acid.

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