Abstract In this article, we propose to make a quantitative definition of catecholamines with respect monoamine biogenic associated, this quantification allows define the alpha and beta scales, which expresses mathematically the correlation group of catecholamines with respect to their common fragment (phenylethylamine) and the tyrosine precursor, in addition performed quantum molecular similarity analysis using four descriptors, quantified by: molecular quantum similarity indices of overlap, Coulomb, overlap‐interaction, Coulomb‐interaction, overlap‐distances Euclidian, and Coulomb‐distances Euclidian, using the topo‐geometrical superposition approach as method of alignment, also proposes a methodology for defining individual groups quantitatively, based on quantum similarity descriptors and supporting the interpretations with experimental results of structural path of reaction. Take in account the importance of creating tools that allow the quantification of biological relationships, and allow the creation of scales of group relations, this scales may be useful in organic synthesis of catecholamines for determine similarities, considering the search for experimental conditions as an area of growing scientific interest. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011