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For almost two centuries, chemists all over the world have applied their expertise and creativity [1–5] to the synthesis of new molecules. Since each individual chemist—or a collaborating group of chemists—tries to select unique synthetic targets [6–9] and come up with a maximally original and/or efficient method of making them, it might appear that the activities of such independent “agents” should be largely uncorrelated, and that no generalizations about the evolution of chemistry en large could be made. As we show here, however, there exist several statistical laws that describe how molecules are made and interconverted. We analyze organic synthesis at the level of an abstract network representation whereby molecules correspond to nodes characterized by molecular masses, and reactions to directed edges connecting these nodes (Figure 1a). We show, among others, that the connections between the nodes form a time-evolving scale free network [10–14] of structure similar to that of the world wide web (WWW),[12, 15, 16] and that masses of molecules in this network are governed by a single stochastic process.[17, 18] Aside from fundamental interest, the trends we identify allow making predictions of potential economical impact for the chemical industry, for example, how many molecules will be synthesized in the future, molecules of which molecular