1. A computer-implemented method to use regular expressions to identify chemical compounds matching specified criteria, comprising: configuring one or more computer processors to perform an operation for searching a plurality of documents which include references to chemical compounds, wherein the references to chemical compounds express the chemical compounds using a plurality of different formats, comprising: receiving the plurality of documents; receiving the criteria specifying desired chemical characteristics; generating at least one regular expression based on the received criteria; evaluating, by operation of the one or more computer processors, chemical compounds referenced in the plurality of documents against the at least one regular expression to identify one or more of the plurality of documents satisfy the received criteria.