The discovery of alternative synthetic routes, or alternative reaction paths, for synthesizing a chemical compound is a subject of vital theoretical importance in synthetic chemistry. It is also a subject of practical importance for developing a chemical process by taking into account such alternative synthetic routes.

Any available set of alternative synthetic routes invariably gives rise to a highly complex reaction network that almost always contains numerous additional synthetic routes resulting from the feasible combinations of the available set; nevertheless, it is extremely difficult, if not impossible, to exhaustively recover the alternative synthetic routes from the complex network. The mathematically exact and computationally efficient approach presented herein resorts to the graph-theoretic method for process-network synthesis based on process graphs (P-graphs). The efficacy of the approach is illustrated with examples.