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Monday, January 14, 2013

Monday's Molecule #197

The last "Monday's Molecule" was β-D-mannopyranose, shown in boat and chair configurations [Monday's Molecule #196]. The winners were Bill Chaney, Dima Klenchin, and Bill Gunn. Bill Gunn should contact me if he is within range of Toronto.

Students often find it very difficult to distinguish between various stereoisomers. For example, many of you thought that the last molecule was glucose. This week's molecule should present a real challenge for most of you. It's a common molecule, present in all cells and it has a common name by which it is identified in most textbooks. However, the common name isn't good enough because there are several different conformations. The conformation shown in the figure is the only one that's synthesized in the normal reaction. Name this molecule using whatever conventions you have to employ to identify it correctly. [Hydrogen atoms are omitted for clarity. You should be able to infer their positions.]

Post your answer as a comment. I'll hold off releasing any comments for 24 hours. The first one with the correct answer wins. I will only post mostly correct answers to avoid embarrassment. The winner will be treated to a free lunch.

There could be two winners. If the first correct answer isn't from an undergraduate student then I'll select a second winner from those undergraduates who post the correct answer. You will need to identify yourself as an undergraduate in order to win. (Put "undergraduate" at the bottom of your comment.)

Some past winners are from distant lands so their chances of taking up my offer of a free lunch are slim. (That's why I can afford to do this!)

In order to win you must post your correct name. Anonymous and pseudoanonymous commenters can't win the free lunch.

Winners will have to contact me by email to arrange a lunch date. Please try and beat the regular winners. Most of them live far away and I'll never get to take them to lunch. This makes me sad.

Comments are now open.
UPDATE: The molecule is 2R,3S-isocitre and the winner is Evey Salara.

Nov. 2009: Jason Oakley, Alex Ling
Oct. 17: Bill Chaney, Roger Fan
Oct. 24: DK
Oct. 31: Joseph C. Somody
Nov. 7: Jason Oakley
Nov. 15: Thomas Ferraro, Vipulan Vigneswaran
Nov. 21: Vipulan Vigneswaran (honorary mention to Raul A. Félix de Sousa)
Nov. 28: Philip Rodger
Dec. 5: 凌嘉誠 (Alex Ling)
Dec. 12: Bill Chaney
Dec. 19: Joseph C. Somody
Jan. 9: Dima Klenchin
Jan. 23: David Schuller
Jan. 30: Peter Monaghan
Feb. 7: Thomas Ferraro, Charles Motraghi
Feb. 13: Joseph C. Somody
March 5: Albi Celaj
March 12: Bill Chaney, Raul A. Félix de Sousa
March 19: no winner
March 26: John Runnels, Raul A. Félix de Sousa
April 2: Sean Ridout
April 9: no winner
April 16: Raul A. Félix de Sousa
April 23: Dima Klenchin, Deena Allan
April 30: Sean Ridout
May 7: Matt McFarlane
May 14: no winner
May 21: no winner
May 29: Mike Hamilton, Dmitri Tchigvintsev
June 4: Bill Chaney, Matt McFarlane
June 18: Raul A. Félix de Sousa
June 25: Raul A. Félix de Sousa
July 2: Raul A. Félix de Sousa
July 16: Sean Ridout, William Grecia
July 23: Raul A. Félix de Sousa
July 30: Bill Chaney and Raul A. Félix de Sousa
Aug. 7: Raul A. Félix de Sousa
Aug. 13: Matt McFarlane
Aug. 20: Stephen Spiro
Aug. 27: Raul A. Félix de Sousa
Sept. 3: Matt McFarlane
Sept. 10: Matt Talarico
Sept. 17: no winner
Sept. 24: Mikkel Rasmussen
Oct. 1: John Runnels
Oct. 8: Raúl Mancera
Oct. 15: Raul A. Félix de Sousa
Oct. 22: Mikkel Rasmussen
Nov. 12: Seth Kasowitz, Bill Gunn
Nov. 19: Michael Rasmussen
Dec. 4: Paul Clapham, Jacob Troth
Dec. 10: Jacob Troth
Dec. 17: Bill Chaney, Dima Klenchin, Bill Gunn
Jan. 14: Evey Salara


Jon Turnbull said...


Anonymous said...


Arek Wittbrodt said...

I'm not sure, but I think it's D-threo-isocitric acid.

Skrithu said...

I believe it is the (S) enantiomer of isocitrate.

Skrithu said...

I noticed the C2 is also a chiral carbon.

Therefore I shall reformulate my answer: it is the 2R,3S enantiomer of isocitrate. I'm not sure if the nomenclature I used is the most correct one.

chemicalscum said...

Trivial name isocitric acid
IUPAC name (1R,2S)-1-hydroxypropane-1,2,3-tricarboxylic acid