Bijvoet

Bijvoet, J.M., Burgers, W.G. and Hagg, G. (1972) Early Papers on Diffraction of X-rays by Crystals (Int. Union of Crystallography, Utrecht) pp. 5. 

The absolute choice between Fischer s two enantiomeric possibilities would not be made for a long time. In 1951, J.M. Bijvoet in Utrecht, the Netherlands, used a new X-ray diffraction tech-... 

One further point needs to be mentioned—the matter of absolute configuration. How do we know that our assignments of R,S configuration are correct in an absolute, rather than a relative, sense Since we can t see the molecules themselves, how do we know that the R configuration belongs to the dextrorotatory enantiomer of lactic acid This difficult question was finally solved in 1951, when J. M. Bijvoet of the University of Utrecht reported an X-ray spectroscopic method for determining the absolute spatial arrangement of atoms in a molecule. Based on his results, we can say with certainty that the R,S conventions are correct. 

Michael reactions and, 895 Beta-keto ester, 851 alkylation of, 859-860 cyclic, 892-893 decarboxylation of, 857, 860 Michael reactions and. 895 pKd of, 852 synthesis of, 892-893 Beta-lactam antibiotics, 824-825 Beta oxidation pathway, 1133-1137 mechanism of, 1133-1136 Beta-pleated sheet (protein), 1038 molecular model of, 1039 secondary protein structure and, 1038-1039 Betaine, 720 Bextra. structure of, 544 BHA, synthesis of, 629 BHT, synthesis of. 629 Bicycloalkane. 129 Bijvoet. J. M., 299 Bimolecular, 363... 

The special X-ray method of Bijvoet gives direct answers and has been used in a number of cases. ... 

Bijvoet, J.M. Peerdeman, A.F. van Bommel, A.J. Nature (London), 1951,168, 271. Fora list of organic structures whose absolute configurations have been determined by this method, see Neidle, S. Rogers, D. Allen, F.H. J. Chem. Soc., C, 1970, 2340. 

The method, also called heavy atom method, consists in introducing a heavy atom in the molecule. Then X-rays with a wave length close to the X-ray absorption of the heavy atom is introduced. As a result a phase shift is superimposed on the ordinary diffraction pattern and configuration is then deduced. The method was first employed in 1951 by Bijvoet et al. to examine sodium rubidium tartrate who concluded that it is possible to differentiate between the two optically active forms. In other words it was possible to determine the absolute configuration of the enantiomers. Since then the absolute configurations of about two hundred optically active compounds have been elucidated by their correlation with other substances of known configuration. 

Since all of the thiol addition products were unknown compounds, except for racemic 3-phenylthiocyclohexanone, it became necessary to devise a method far determining the absolute configuration without resorting to Bijvoet s method (53) for each new compound (see Table 4). This was accomplished by preparing the thioacetal of the adamantanedione, a model 3-thiosubstituted cyclohexanone of known absolute configuration (54) (eq. [10]). 

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