The bimolecular nucleophilic substitution reaction at saturated carbon is an icon of organic chemistry, and is better known by its mechanistic label, S _N 2 . It is normally a slow reaction, with half lives often measured in hours.

Chemistry can be very focussed nowadays. This especially applies to target-driven synthesis, where the objective is to make a specified molecule, in perhaps as an original manner as possible. A welcome, but not always essential aspect of such syntheses is the discovery of new chemistry.

The science journal is generally acknowledged as first appearing around 1665 with the Philosophical Transactions of the Royal Society in London and (simultaneously) the French Academy of Sciences in Paris. By the turn of the millennium, around 10,000 science and medical journals were estimated to exist.

One of the many clever things that clever people can do with the Web is harvest it, aggregate it, classify it etc. Its not just Google that does this sort of thing! Egon Willighagen is one of those clever people. He runs the Chemical blogspace which does all sorts of amazing things with blogs.

Chemical bonds can be assembled from components which chemists know as σ, π and δ. The blog poses the question whether any bonds can be constructed which use a fourth type of component, the φ.

An earlier post described how a (spherical) halide anion fitted snugly into a cavity generated by the simple molecule propanone, itself assembled by sodium cations coordinating to the oxygen.

The iconic diagram below represents a cornerstone of organic chemistry.

This story starts with an organic chemistry tutorial, when a student asked for clarification of the  Finkelstein reaction. This is a simple S _N 2 type displacement of an alkyl chloride or bromide, using sodium iodide in acetone solution, and resulting in an alkyl iodide. What was the driving force for this reaction he asked?

In the previous post,  it was noted that  Möbius annulenes are intrinsically chiral, and should therefore in principle be capable of resolution into enantiomers. The synthesis of such an annulene by Herges and co-workers was a racemic one; no attempt was reported at any resolution into such enantiomers. Here theory can help, since calculating the optical rotation [α]D is nowadays a relatively reliable process for rigid molecules.

Much like climbing Mt. Everest because its there,  some hypothetical molecules are just too tantalizing for chemists to resist attempting a synthesis. Thus in 1964, Edgar Heilbronner  speculated on whether a conjugated annulene ring might be twistable into a  Möbius strip. It was essentially a fun thing to try to do, rather than the effort being based on some anticipated  (and useful) property it might have.

In 1988, Wilke[cite]10.1002/anie.198801851[/cite] reported molecule 1 It was a highly unexpected outcome of a nickel-catalyzed reaction and was described as a 24-annulene with an unusual 3D shape. Little attention has been paid to this molecule since its original report, but the focus has now returned!