✍ Scribed by Bradford P. Cross; Thomas Schleich
No coin nor oath required. For personal study only.
The temperature dependence of the chemical shifts of ten commonly employed ^1^H n.m.r. reference compounds of interest to both organic and biological workers was determined using the temperature independent standard ethane at low density. The water soluble standards sodium 2,2‐dimethyl‐2‐silapentane‐5‐sulfonate and sodium 3‐trimethylsilylpropionate‐d~6~ exhibited very small chemical shift changes over the range of 20–65 °C. Outside of this temperature interval the chemical shift is distinctly nonlinear, but still is sufficiently small to be neglected for many n.m.r. studies. In contrast, the temperature dependence of seven neat organic liquid reference standards was observed to be linear over a significant temperature range with slopes varying between 0.0009 and 0.0023 ppm °C^−1^. Only tetramethylammonium chloride (in ^2^H~2~O) exhibited a small but pronounced nonlinear temperature dependence over the full range investigated.
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