Through the looking-glass challenge

Analytical and Bioanalytical Chemistry, Sep 2017

Reinhard Meusinger

A PDF file should load here. If you do not see its contents the file may be temporarily unavailable at the journal website or you do not have a PDF plug-in installed and enabled in your browser.

Alternatively, you can download the file locally and open with any standalone PDF reader:

https://link.springer.com/content/pdf/10.1007%2Fs00216-017-0539-8.pdf

Through the looking-glass challenge

Chemistry” (ABC) homepage at http://www.springer.com/ abc and in the journal (volume 410/issue 10) Through the looking-glass challenge Reinhard Meusinger 0 0 Institute of Organic Chemistry and Biochemistry, Darmstadt University of Technology , Alarich-Weiss-Str. 4, 64287 Darmstadt , Germany 1 Reinhard Meusinger We would like to invite you to participate in the Analytical Challenge, a series of puzzles to entertain and challenge our readers. This special feature of “Analytical and Bioanalytical Chemistry” (ABC) has established itself as a truly unique quiz series, with a new scientific puzzle published every other month. Readers can access the complete collection of published problems with their solutions on the ABC homepage at http://www.springer.com/abc.Test your knowledge and tease your wits in diverse areas of analytical and bioanalytical chemistry by viewing this collection. In the present challenge, spectroscopy is the topic. And please note that there is a prize to be won (a Springer book of your choice up to a value of €100). Please read on… scientific explanation. In 1849 Louis Pasteur noticed that the crystals of tartaric acid come in two asymmetric forms that are mirror images of one another. He deduced that the molecule in question is asymmetric and could exist in two different forms that resemble one another as would left- and right-hand gloves. The theoretical explanation for this phenomenon was given by van 't Hoff [1] and Le Bel [2] 3 years later in 1874. - Meet the challenge “How would you like to live in Looking-Glass House, Kitty?” Alice asked her cat in the novel Through the Looking-Glass, and What Alice Found There (1871). Only 6 years after Alice had experienced her adventures in Wonderland, the author Lewis Carroll (Charles Lutwidge Dodgson) lets Alice enter another fantastical world, this time by her climbing through a mirror into another world. “I wonder if they’d give you milk in there? Perhaps Looking-Glass milk isn’t good to drink…” Alice says questioningly to her cat. Specular optical activity had been known for a while then, yet it was still lacking The compound we are looking for in this challenge exists in two mirror-image forms as well. One of these forms rotates the plane of polarization of linearly polarized light clockwise (we will call it the (+)-compound) and the other rotates it counterclockwise (the (−)-compound). An interesting feature of these two forms is that they differ significantly in their smell and taste. Hence, it should not come as a surprise that both compounds are found separately in different plants, although they also exist as a racemic mixture. The name of this substance derives from one of the oldest known medicinal plants, which contains a particularly high proportion of it in its seeds. Seeds of this plant have been found at excavations of 3000-year-old pile dwellings. Today, this plant is widely cultivated throughout practically all of Europe. However, the global leader in the seed oil export of this plant is a Scandinavian country with long hours of sunlight during the summer, which leads to fruits with higher levels of essential oil. The fruits and the essential oil are used in many ways in cooking and in the preparation of certain medicines and liqueurs. The fruits are used in breads, cheeses, and even desserts, whereas the fruit oil is used as a fragrance in soaps, lotions, and breath fresheners, and has a long tradition of use in folk medicine. The etymology of the name of this miracle-working plant is complex and poorly understood, because it has been called by Fig. 1 The 500-MHz 1H-NMR spectra of both optical isomers, measured in dimethyl-d6 sulfoxide. The spectrum of the (+)-compound is colored blue and the mirrored spectrum of the (−)compound is colored red many names in different regions, with names deriving from Arabic, Greek, which was adapted into Latin, and Sanskrit. The English use of the name dates back to the middle of the fifteenth century and is considered to be of Arabic origin, probably. To the best of our knowledge, the compound we are looking for was first isolated in 1840 from its essential oil, and Berzelius named it by suffixing “ol” to the plant’s Latin name. The difference between two compounds, both isolated from essential oils, was described in 1876 as “Y is already Fig. 2 The spectra from Fig. 1 in greater detail distinguished physically from X by the fact that it penetrates much less into cork, and does not show the property of gnashing when rubbing on a glass bottleneck, like X and other thin-liquid essential oils” [ 3 ]. Despite the difficulty in determining the structure, the empirical formula was determined correctly as C10H14O. Today, structural analysis is facilitated greatly by use of spectroscopic methods. First, we look at the 1H-NMR spectrum of the substance, measured in dimethyl-d6 sulfoxide. In Figs. 1 and 2, the 1H-NMR spectra of both optical forms are shown in an unusual mirrored manner, in which (...truncated)


This is a preview of a remote PDF: https://link.springer.com/content/pdf/10.1007%2Fs00216-017-0539-8.pdf

Reinhard Meusinger. Through the looking-glass challenge, Analytical and Bioanalytical Chemistry, 2017, pp. 5795-5798, Volume 409, Issue 25, DOI: 10.1007/s00216-017-0539-8