Here I offer another spin-off from writing a lecture course on conformational analysis. This is the famous example of why 1,2-difluoroethane adopts a gauche rather than antiperiplanar conformation.

One of the (not a few) pleasures of working in a university is the occasional opportunity that arises to give a new lecture course to students.

One future vision for chemistry over the next 20 years or so is the concept of having machines into which one dials a molecule , and as if by magic, the required specimen is ejected some time later. This is in some ways an extrapolation of the existing peptide and nucleotide synthesizer technologies and sciences.

Stoyanov, Stoyanova and Reed recently published on the structure of the hydrogen ion in water.

In the previous post, I ruminated about how chemists set themselves targets. Thus, having settled on describing regions between two (and sometimes three) atoms as bonds , they added a property of that bond called its order . The race was then on to find molecules which exhibit the highest order between any particular pair of atoms.

Climbers scale Mt. Everest, because its there , and chemists have their own version of this. Ever since G. N. Lewis introduced the concept of the electron-pair bond in 1916, the idea of a bond as having a formal bond-order has been seen as a useful way of thinking about molecules. The initial menagerie of single, double and triple formal bond orders (with a few half sizes) was extended in the 1960s to four, and in 2005 to five.

In an earlier post, I re-visited the conformational analysis of cyclohexane by looking at the vibrations of the entirely planar form (of D _6h symmetry). The method also gave interesting results for the larger cyclo-octane ring. How about a larger leap into the unknown? Let us proceed as follows. One fun game to play in chemistry is to invoke i so-electronic substitutions.

Scientists write blogs for a variety of reasons. But these do probably not include getting tenure (or grants). For that one has to publish.

In the previous post, I suggested that inspecting the imaginary modes of planar cyclohexane might be a fruitful and systematic way in which at least parts of the conformational surface of this ring might be probed.

Like benzene, its fully saturated version cyclohexane represents an icon of organic chemistry. By 1890, the structure of planar benzene was pretty much understood, but organic chemistry was still struggling somewhat to fully embrace three rather than two dimensions. A grand-old-man of organic chemistry at the time, Adolf von Baeyer, believed that cyclohexane too was flat, and what he said went.