Chemistry That Misses The Mark

In the July 27 issue of C&EN (page 5), Jane Griffin cites the fact that the Nobel Prize in Chemistry was awarded to Heinrich Wieland and Adolf Windaus (in 1927 and 1928, respectively) for the wrong structure of cholesterol. She also notes that, on the basis of J. D. Bernal’s X-ray work, Wieland and Elisabeth Dane corrected the structure in 1932. I have found this to be an excellent example to teach students how you can go wrong by extrapolating too far.

Wieland and Windaus were misled by applying H. G. Blanc’s rule on the ring closure of dicarboxylic acids (Compt. Rend.1907,144, 1356). This rule was developed for open-chain dicarboxylic acids and failed when ring systems were involved.

I cited this to my biochemistry students in the context of a problem on sequence determination of a cyclic peptide (gramicidin). The textbook stated that when proline is next to an amino acid, which is normally cleaved by trypsin or chymotrypsin, that bond is not cleaved. That rule was developed for linear peptides and failed for this cyclic peptide.

Blanc’s rule has disappeared from chemistry, and my junior colleagues have never heard of it. Also, in light of this and other errors for premature awards, the Nobel Committee for Chemistry now waits many years until discoveries are well vetted before making an award.

Donald D. Clarke
Bronx, N.Y.