Orthosilicate

Structure of the anion

In chemistry, orthosilicate is the anion SiO4−
4, or any of its salts and esters. It is one of the silicate anions. It is occasionally called the silicon tetroxide anion or group.[1]

Orthosilicate salts, like sodium orthosilicate, are stable, and occur widely in nature as silicate minerals, being the defining feature of the nesosilicates.[2] Olivine, a magnesium or iron(II) orthosilicate, is the most abundant mineral in the upper mantle.

The orthosilicate anion is a strong base, the conjugate base of the extremely weak orthosilicic acid H
4SiO
4 (pKa2 = 13.2 at 25 °C). This equilibrium is difficult to study since the acid tends to decompose into a hydrated silica condensate.[3]

  1. ^ C. A. Kumins, and A. E. Gessler (1953), "Short-Cycle Syntheses of Ultramarine Blue". Indunstrial & Engineering Chemistry, volume 45, issue 3, pages 567–572. doi:10.1021/ie50519a031
  2. ^ Western Oregon University
  3. ^ Jurkić, Lela Munjas; Cepanec, Ivica; Pavelić, Sandra Kraljević; Pavelić, Krešimir (2013). "Biological and therapeutic effects of ortho-silicic acid and some ortho-silicic acid-releasing compounds: New perspectives for therapy". Nutrition & Metabolism. 10 (1): 2. doi:10.1186/1743-7075-10-2. ISSN 1743-7075. PMC 3546016. PMID 23298332.