376 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1961 



whether a wholly satisfactory solution to these problems has yet been 

 found. 



These three, admittedly somewhat arbitrary, divisions of organic 

 chemistry represent the main lines of advance which, by their progress 

 and interplay, have brought organic chemistry to its present level in 

 the academic and industrial fields. 



NEW TECHNIQUES 



One final point regarding their development should, however, be 

 made. All three divisions have owed much to the successive introduc- 

 tion of new techniques and indeed without the development of micro- 

 analytical methods, chromatography — paper, ion-exchange, and 

 more recently vapor-phase ^ — and the introduction of physical 

 methods of analysis and identification using spectroscopy in its various 

 forms as well as X-ray crystallography, none of them could have 

 reached its present position. "Wliat has been achieved and how far 

 can one estimate from the answer to that question the outlook for the 

 future ? 



Carbon compounds both natural and synthetic fall into two great 

 groups. The first comprises those substances whose molecules can 

 be regarded as units in themselves ; these are of relatively low molec- 

 ular weight varying from methane (CH4) with a molecular weight 

 of 16 to vitamin Bio(Cg3H88Ni40i4PCo) with one of 1354. The 

 second group is that of the so-called macromolecules which includes 

 inter alia the polysaccharides, proteins, nucleic acids, and rubber 

 among natural products, and the synthetic polymers and plastics 

 among synthetic materials. These substances have very large mole- 

 cules, and their molecular weight may run into millions, as in the 

 case of nucleic acids. It is characteristic of them that they are made 

 up of a very large number of small unit molecules all joined together 

 in a more or less regular manner by processes of polymerization or 

 polycondensation. Since substances of the second group cannot 

 normally be purified by the traditional methods of crystallization 

 or distillation it is not surprising that most of the progress in organic 

 chemistry has hitherto been in the field of the relatively small "unit" 

 molecules. 



There indeed it has been spectacular. The structures of a very 

 large number of complex natural products have been worked out — 

 vitamins, hormones, antibiotics, alkaloids, steroids, coenzymes, etc. — 

 and most of them have been synthesized; many, indeed, are today 

 manufactured by synthesis on a commercial scale. The power of 

 modern organic synthesis has been amply demonstrated in recent 



= See, for example. "A New Kind of Chromatogram," by A. T. James, In No. 16 of The 

 Times Science Review, London, Summer, 1955. 



