ORGANIC CHEMISTRY — TODD 377 



years by such achievements as the total synthesis of steroids, such as 

 cholesterol and cortisone, of chlorophyll, of cozyniase, and of alka- 

 loids such as strychnine. Synthetic methods have indeed reached 

 such a level of perfection that very few structures would seem be- 

 yond their grasp. Structural determination, which in natural-prod- 

 uct chemistry usually precedes synthesis, has in the past 10 years 

 or so made enormous strides by the introduction of new physical 

 methods based on ultraviolet, infrared, and nuclear magnetic reso- 

 nance spectroscopy, and on X-ray crystallography. The power of 

 the last-named analytical tool is amply demonstrated in the brilliant 

 work of Prof. D. Crowfoot Hodgkin on the structure of vitamin B12. 

 Such techniques have already rendered obsolescent many of the 

 older degradative methods of the organic chemist — in whicli the 

 structure of a complex molecule was arrived at by a study of the 

 breakdown products formed from it in different conditions — and fur- 

 ther advances in the same direction may be expected from the newer 

 applications of mass spectroscopy which enables a mixture of mole- 

 cules to be separated on the basis of their respective masses. The 

 flowering of structural and synthetic chemistry is reflected in the 

 triumphs of the allied industrj^ — the stream of synthetic drugs which 

 have given for the first time cures rather than palliatives for many 

 diseases, pesticides and herbicides, new dyes of vastly improved per- 

 formance, as well as detergents and a host of other materials now 

 regarded as normal features in our daily life. Moreover, the spec- 

 tacular development of catalytic methods of synthesis and degra- 

 dation in the field of petroleum chemistry has led not only to the 

 appearance of a wealth of new intermediates for the chemical industry, 

 but also to a gradual ousting of coal in favor of petroleum as its raw 

 material. 



MACROMOLECULES 



Progress in the study of macromolecular substances was, until com.- 

 paratively recently, very slow, largely because of the absence of 

 experimental tecliniques for dealing with them. But with the ap- 

 pearance of the newer physical tecliniques of separation, study of the 

 natural macromolecules both by degradation and synthesis has begun 

 to grow very rapidly. Among the more spectacular developments 

 have been the structural elucidation of a number of protein or poly- 

 peptide hormones including insulin and the total synthesis of a num- 

 ber of the smaller members of the group such as vasopressin. Sub- 

 stantial progress is now being made in determining the structure of 

 the larger natural proteins, a striking example being provided by 

 the very recent work on myoglobin structure ^ using X-ray methods 



* See, for example, "Molecules of Life" in No. 28 of The Times Science Review, London, 

 Summer, 1958, and the model of the structure of myoglobin reproduced in No. 37, Autumn, 

 1960. p. 1. 



