What molecule am I?
Butane is a linear saturated hydrocarbon that is a gas under standard conditions of temperature and pressure, but it is easily liquefied. It has been known since at least 1849, when British organometallic chemistry pioneer Edward Frankland unknowingly prepared it via the reaction of iodoethane1 and metallic zinc when he thought that he isolated the ethyl radical.
In 1879, British chemist J. W. Thomas mentioned butane in an article about the analysis of combustible gases. During the late 1800s, notable chemists such as Lothar Meyer (Germany) and William Henry Perkin (Britain) investigated various properties of butane.
Butane is familiar to many people as a major component of gasoline, as a fuel for camping stoves, and as a lighter fluid. But this past July, a very different use for the hydrocarbon came to light. Nuwandi M. Ariyasingha and Eduard Y. Chekmenev at Wayne State University (Detroit) and 14 colleagues there and at the International Tomography Center (Novosibirsk, Russia) and Southern Illinois University (Carbondale) reported the development of hyperpolarized butane for use in ventilated lung imaging.
Proceeding on the finding that NMR hyperpolarization dramatically improves the detection sensitivity of magnetic resonance by increasing nuclear spin polarization, the researchers sought a way to replace US Food and Drug Administration–approved hyperpolarized xenon-1292 for the magnetic resonance imaging of lungs. They first found that proton-hyperpolarized propane gas worked well, but they also discovered that the propane’s hyperpolarization decays too rapidly to be used in clinical practice.
The authors then turned to hyperpolarized butane, which they generated via heterogeneous parahydrogen3–induced polarization, using a rhodium nanoparticle–based catalyst and butene gas as a precursor for parahydrogen addition to form butane. They found that hyperpolarized butane could be produced much faster than its propane analogue, and its usable lifetime was twice that of hyperpolarized propane.
The authors concluded, “The demonstrated results have the potential to revolutionize functional pulmonary imaging with a simple and inexpensive on-demand production of proton-hyperpolarized gas [butane] contrast media, followed by visualization on virtually any MRI scanner, including emerging bedside low-field MRI scanner technology.”
1. CAS Reg. No. 76-03-6.
2. CAS Reg. No. 13965-99-6. Hyperpolarized 129Xe is expensive to prepare and cannot be used in conventional clinical MRI scanners.
3. The nuclear spin isomer of normal orthohydrogen.
Butane hazard information
| Hazard class* | GHS code and hazard statement | |
|---|---|---|
| Flammable gases, category 1 | H220—Extremely flammable gas |  |
| Gases under pressure (liquefied gas) | H280—Contains gas under pressure; may explode if heated |  |
| Simple asphyxiant, category 1 | [No code]—May displace oxygen and cause rapid suffocation | |
*Globally Harmonized System (GHS) of Classification and Labeling of Chemicals. Explanation of pictograms.
Molecules from the Journals
Gallium sulfur iodide1 (GaSI) is an inorganic compound that was first described in 1963 by Harry Hahn* and Hartmut Katscher at the University of Würzburg (then in West Germany) in a treatise on the preparation of numerous gallium chalcogenide halides. They synthesized the compounds by heating mixtures of the individual elements, gallium chalcogenides, and gallium halides and described their properties.
Fast forward to this past July, when Maxx Q. Arguilla and 10 co-workers at the University of California, Irvine, reported the preparation of a GaSI crystal with an unusual structure. They crystallized GaSI in the form of non-centrosymmetric helical chains with what they describe as “squircular” cross-sections. Among other desirable properties, the crystals have a large 3.69-eV bandgap. The authors believe that their results “position GaSI as a promising exfoliable nonlinear optical material across a broad optical window.”
Osmium(III) acetylacetonate2 [Os(acac)3] is an inorganic–organic complex that appeared in a 1965 study of its near-IR absorption spectrum by R. Dingle at the University of Western Australia (Nedlands). The author used data from the spectrum to predict the magnetic susceptibility of the complex, which was in good agreement with the experimental value.
Os(acac)3 made few appearances in the literature until 2022, when Anastasia Borschevsky at the University of Groningen (The Netherlands) and collaborators there and at institutions in Switzerland, France, Belgium, New Zealand, and Slovakia reported a theoretical and experimental investigation of the helically chiral Os(acac)3 and its cousin ruthenium acetylacetonate3 [Ru(acac)3] to detect molecular parity violations in their vibrational (IR) spectra. The authors’ experiments resulted in progress made toward identifying vibrational modes that pinpoint transitions with large parity violation shifts.
Finally, Mauro Perfetti and colleagues at the University of Florence (Italy) delved into the mystery of the “missing” β-polymorph of Os(acac)3. They used magnetic measurements on the complex’s crystalline powder, cantilever torque magnetometry on a single crystal, and electron paramagnetic spectroscopy to ascertain that the polymorph’s heretofore unknown structure is orthorhombic, analogous to that of Ru(acac)3, mentioned above. The authors’ study showed that all acetylacetonate complexes of group 8 elements of the periodic table exhibit dimorphism and are isomorphic.
1. CAS Reg. No. 56891-76-0.
2. CAS Reg. No. 15635-86-6.
3. CAS Reg. No. 14284-93-6.
Molecules from the Journals
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Butane fast facts
| CAS Reg. No. | 106-97-8 |
| SciFindern name | Butane |
| Empirical formula | C4H10 |
| Molar mass | 58.12 g/mol |
| Appearance | Colorless gas or liquid |
| Boiling point | –0.5 °C |
| Water solubility | 60 mg/L (25 °C) |
Learn more about this molecule from CAS, the most authoritative and comprehensive source for chemical information.
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