Quinquevalent phosphorus acids
This chapter covers scientific contributions in quinquevalent organo-phosphorus chemistry published in the literature in 2018. The chapter describes compounds possessing three P–O bonds (phosphates), two P–O and one P–C bonds (phosphonates) as well as one P–O and two P–C bonds (phosphinates) in addition to the phosphoryl group PO. Heteroanalogs of phosphates, phosphinates and phosphonates containing combinations of P–X and PY bonds (X,Y=O, N, S, Se) has also been described, usually in the end of subsections, in this year they are marked as phosphates, phosphonates and phosphinate hetero-anolgs. Each of the main sections has been divided in the same way, covering synthesis, reactions and biological aspects of phosphoric, phosphonic and phosphinic acids and their derivatives. As in the last three years, additional subsections devoted to miscellaneous applications, other than biological ones, have been added in all three sections devoted to phosphates, phosphonates and phosphinates. In this year, we propose a new subsections division due to the fact that it is often impossible to separate synthesis from further reactions, synthesis from biological and miscellaneous applications. Therefore, in order to improve transparency of the reviewed material, each section has been subdivided onto “synthesis and reactions” including pure synthesis without applications (single- or multis-step), “synthesis and biological or miscellaneous applications” including synthesis, irrespective of the number of stages, which was aimed at further applications research.