Orthosilicic acid

Orthosilicic acid (/ˌɔːrθəsɪˈlɪsɪk/) is an inorganic compound with the formula Si(OH)4. Although rarely observed, it is the key compound of silica and silicates and the precursor to other silicic acids [H2xSiOx+2]n. Silicic acids play important roles in biomineralization and technology.[1][2][3]

Orthosilicic acid
Names
IUPAC name
Orthosilicic acid
Other names
Silicic acid
Identifiers
CAS Number
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.030.421
EC Number
  • 233-477-0
Gmelin Reference
 2009
PubChem CID
UNII
InChI
  • InChI=1S/H4O4Si/c1-5(2,3)4/h1-4H Y
    Key: RMAQACBXLXPBSY-UHFFFAOYSA-N Y
  • InChI=1S/H4O4Si/c1-5(2,3)4/h1-4H
    Key: RMAQACBXLXPBSY-UHFFFAOYSA-N
  • InChI=1/H4O4Si/c1-5(2,3)4/h1-4H
    Key: RMAQACBXLXPBSY-UHFFFAOYAS
SMILES
  • O[Si](O)(O)O
Properties
Chemical formula
 H4O4Si
Molar mass 96.113 g·mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N (what is YN ?)
Infobox references

Isolation
Structure of Si(OH)4 stabilized by two chloride anions.

Typically orthosilicic acid is assumed to be a product of the hydrolysis of the ortho esters Si(OCR)4, as is practiced in sol-gel syntheses.[1] These conditions are however too vigorous to allow isolation of the parent acid.

Orthosilicic acid can be produced by Pd-catalyzed hydrogenolysis of tetrabenzoxysilicon:[4]

Si(OCH2Ph)4 + 4 H2 → Si(OH)4 + 4 CH3Ph

The acid was crystallized from a solution of dimethylacetamide and tetrabutylammonium chloride. As established by X-ray crystallography, the chloride anions interact with the acid via hydrogen bonds. Otherwise, the structure consists of the expected tetrahedral silicon center.

Reactions
Chemical structure of Si4O4(OH)8.

Silicic acid readily condenses to give "higher" silicic acids including disilicic and cyclic-tetrasilicic acid:[4]

2 Si(OH)4 → O(Si(OH)3)2 + H2O
4 Si(OH)4 → (OSi(OH)2)4 + 4 H2O

These derivatives have also been characterized crystallographically.


Orthosilicic acid in plants

Silicon has been explored as a nutrient for plant growth, with silica comprising up to 10% of plant weight on a dry matter basis.[5] Orthosilicic acid is of particular interest as it is thought to be the form in which plants uptake silicon from the soil,[6][7] before being deposited as phytoliths throughout the plant, leading to research in the application of orthosilicic acid through foliar sprays to supplement plant growth.[8] Studies have demonstrated that foliar application of stabilized orthosilicic acid can alleviate abiotic stressors such as drought,[9][10] heavy metal toxicity,[11][12] and salinity,[13] resulting in increased yields.[14] Additionally, applications of orthosilicic acid have been demonstrated to reduce fungal infections and disease in plants,[15] suggesting the possibility of using stabilized orthosilicic acid as an alternative or complement to existing disease control measures. The mechanisms by which orthosilicic acid alleviates abiotic stress and controls diseases is not well understood; current theories advanced include the activation of plant defense reactions[16] and the precipitation of silica in the apoplast of the plant.[17]

Oceanic silicic acid
2009 silicic acid concentration in the upper pelagic zone.[18]

Dissolved silica (DSi) is a term used in the field of oceanography to describe the form of water-soluble silica, which is assumed to be Si(OH)
4 (orthoslicic acid) or its conjugate bases (orthosilicate anions) such as Si(OH)
3O−
 and Si(OH)
2O2−
2. Theoretical computations indicate that the dissolution of silica in water proceeds through the formation of a SiO
2·2H
2O complex and then orthosilicic acid.[19] The biogeochemical cycle of silica is regulated by the algae known as the diatoms.[20][21] These algae polymerise the silicic acid to so-called biogenic silica, used to construct their cell walls (called frustules).[22]

In the uppermost water column the surface ocean is undersaturated with respect to dissolved silica, except for the Antarctic Circumpolar Current south of 55°S.

The dissolved silica concentration increases with increasing water depth, and along the conveyor belt from the Atlantic over the Indian into the Pacific Ocean.[23][24]

References
  1. N. N. Greenwood, A. Earnshaw, Chemistry of the Elements, 2nd ed., Butterworth-Heinemann, Oxford, UK, 1997.
  2. R. K. Iler, The Chemistry of Silica, Wiley, New York, 1979.
  3. Gerhard Lagaly, Werner Tufar, A. Minihan, A. Lovell (2007). "Silicates". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a23_661.{{cite encyclopedia}}: CS1 maint: multiple names: authors list (link)
  4. Igarashi, Masayasu; Matsumoto, Tomohiro; Yagihashi, Fujio; Yamashita, Hiroshi; Ohhara, Takashi; Hanashima, Takayasu; Nakao, Akiko; Moyoshi, Taketo; Sato, Kazuhiko; Shimada, Shigeru (2017). "Non-aqueous selective synthesis of orthosilicic acid and its oligomers". Nature Communications. 8: 140. Bibcode:2017NatCo...8..140I. doi:10.1038/s41467-017-00168-5. PMID 28747652. S2CID 3832255.
  5. Farooq, Muhammad Ansar; Dietz, Karl-Josef (12 Nov 2015). "Silicon as Versatile Player in Plant and Human Biology: Overlooked and Poorly Understood". Frontiers in Plant Science. Frontiers Media SA. 6. doi:10.3389/fpls.2015.00994. ISSN 1664-462X.
  6. Souri, Zahra; Khanna, Kanika; Karimi, Naser; Ahmad, Parvaiz (14 Jun 2020). "Silicon and Plants: Current Knowledge and Future Prospects". Journal of Plant Growth Regulation. Springer Science and Business Media LLC. 40 (3): 906–925. doi:10.1007/s00344-020-10172-7. ISSN 0721-7595.
  7. MA, Jian Feng; YAMAJI, Naoki; MITANI-UENO, Namiki (2011). "Transport of silicon from roots to panicles in plants". Proceedings of the Japan Academy, Series B. Japan Academy. 87 (7): 377–385. doi:10.2183/pjab.87.377. ISSN 0386-2208.
  8. Laane, Henk-Maarten (7 Jun 2018). "The Effects of Foliar Sprays with Different Silicon Compounds". Plants. MDPI AG. 7 (2): 45. doi:10.3390/plants7020045. ISSN 2223-7747.
  9. Ratnakumar, P.; Deokate, P.P.; Rane, J.; Jain, N.; Kumar, V.; Berghe, D.V.; Minhas, P.S. (2016). "Effect of Ortho-Silicic Acid Exogenous Application on Wheat (Triticum aestivumL.) under Drought". Journal of Functional And Environmental Botany. Diva Enterprises Private Limited. 6 (1): 34. doi:10.5958/2231-1750.2016.00006.8. ISSN 2231-1742.
  10. Goyal, Vinod; Baliyan, Vaibhav; Avtar, Ram; Mehrotra, Shweta (20 Aug 2022). "Alleviating Drought Stress in Brassica juncea (L.) Czern & Coss. by Foliar Application of Biostimulants—Orthosilicic Acid and Seaweed Extract". Applied Biochemistry and Biotechnology. Springer Science and Business Media LLC. doi:10.1007/s12010-022-04085-2. ISSN 0273-2289.
  11. Dwivedi, Sanjay; Kumar, Amit; Mishra, Seema; Sharma, Pragya; Sinam, Geetgovind; Bahadur, Lal; Goyal, Vinod; Jain, Neeru; Tripathi, Rudra Deo (17 Apr 2020). "Orthosilicic acid (OSA) reduced grain arsenic accumulation and enhanced yield by modulating the level of trace element, antioxidants, and thiols in rice". Environmental Science and Pollution Research. Springer Science and Business Media LLC. 27 (19): 24025–24038. doi:10.1007/s11356-020-08663-x. ISSN 0944-1344.
  12. Imtiaz, Muhammad; Rizwan, Muhammad Shahid; Mushtaq, Muhammad Adnan; Ashraf, Muhammad; Shahzad, Sher Muhammad; Yousaf, Balal; Saeed, Dawood Anser; Rizwan, Muhammad; Nawaz, Muhammad Azher; Mehmood, Sajid; Tu, Shuxin (2016). "Silicon occurrence, uptake, transport and mechanisms of heavy metals, minerals and salinity enhanced tolerance in plants with future prospects: A review". Journal of Environmental Management. Elsevier BV. 183: 521–529. doi:10.1016/j.jenvman.2016.09.009. ISSN 0301-4797.
  13. Coskun, Devrim; Britto, Dev T.; Huynh, Wayne Q.; Kronzucker, Herbert J. (18 Jul 2016). "The Role of Silicon in Higher Plants under Salinity and Drought Stress". Frontiers in Plant Science. Frontiers Media SA. 7. doi:10.3389/fpls.2016.01072. ISSN 1664-462X.
  14. Artyszak, Arkadiusz; Gozdowski, Dariusz (23 Jul 2021). "Influence of Various Forms of Foliar Application on Root Yield and Technological Quality of Sugar Beet". Agriculture. MDPI AG. 11 (8): 693. doi:10.3390/agriculture11080693. ISSN 2077-0472.
  15. Sharma, Divya; Sangwan, Sanyukta; Jain, Neeru (8 Sep 2020). "Antifungal Activity of Stabilized Ortho Silicic Acid (OSA) against Foliar Plant Pathogens". Silicon. Springer Science and Business Media LLC. 13 (11): 3807–3815. doi:10.1007/s12633-020-00628-6. ISSN 1876-990X.
  16. Fauteux, François; Rémus-Borel, Wilfried; Menzies, James G.; Bélanger, Richard R. (2005). "Silicon and plant disease resistance against pathogenic fungi". FEMS Microbiology Letters. Oxford University Press (OUP). 249 (1): 1–6. doi:10.1016/j.femsle.2005.06.034. ISSN 0378-1097.
  17. Coskun, Devrim; Deshmukh, Rupesh; Sonah, Humira; Menzies, James G.; Reynolds, Olivia; Ma, Jian Feng; Kronzucker, Herbert J.; Bélanger, Richard R. (14 Jul 2018). "The controversies of silicon's role in plant biology". New Phytologist. Wiley. 221 (1): 67–85. doi:10.1111/nph.15343. ISSN 0028-646X.
  18. Information, US Department of Commerce, NOAA National Centers for Environmental. "World Ocean Atlas 2009". www.nodc.noaa.gov. Retrieved 17 April 2018.
  19. Bhaskar Mondal, Deepanwita Ghosh, and Abhijit K. Das (2009): "Thermochemistry for silicic acid formation reaction: Prediction of new reaction pathway". Chemical Physics Letters, volume 478, issues 4–6, pages 115-119. doi:10.1016/j.cplett.2009.07.063
  20. Siever, R. (1991). Silica in the oceans: biological-geological interplay. In: Schneider, S. H., Boston, P. H. (eds.), Scientists On Gaia, The MIT Press, Cambridge MA, USA, pp. 287-295.
  21. Treguer, P., Nelson, D. M., Van Bennekom, A. J., DeMaster, D. J., Leynaert, A. Queguiner, B. (1995). "The silica balance in the world ocean: A reestimate". Science. 268 (5209): 375–379. doi:10.1126/science.268.5209.375. PMID 17746543.{{cite journal}}: CS1 maint: uses authors parameter (link)
  22. Del Amo, Y., and M. A. Brzezinski. 1999. The chemical form of dissolved Si taken up by marine diatoms. J. Phycol. 35:1162-1170. https://onlinelibrary.wiley.com/doi/10.1046/j.1529-8817.1999.3561162.x/abstract
  23. The figures here have been drawn using the interactive web site which feeds on annual DSi values from LEVITUS94: World Ocean Atlas 1994, an atlas of objectively analyzed fields of major ocean parameters at the annual, seasonal, and monthly time scales. Superseded by WOA98. Edited by Syd Levitus.
  24. "World Ocean Atlas 1994".
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