Silicic acid

Silicic acid
Silicic acid
CAS number 10193-36-9 YesY
PubChem 14942 YesY
ChemSpider 14236 YesY
EC number 233-477-0
ChEBI CHEBI:266​75 YesY
Gmelin Reference 2009
Jmol-3D images Image 1
Molecular formula H4O4Si
Molar mass 96.11 g mol−1
Exact mass 95.987885149 g mol-1
Acidity (pKa) 9.84, 13.2
 N acid (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references
Annual mean sea surface silicic acid for the World Ocean. Data from the World Ocean Atlas 2005.

Silicic acid is a general name for a family of chemical compounds of the element silicon, hydrogen, and oxygen, with the general formula [SiOx(OH)4-2x]n.[1][2] Some simple silicic acids have been identified in very dilute aqueous solution, such as metasilicic acid (H2SiO3), orthosilicic acid (H4SiO4, pKa1=9.84, pKa2=13.2 at 25°C), disilicic acid (H2Si2O5), and pyrosilicic acid (H6Si2O7); however in the solid state these probably condense to form polymeric silicic acids of complex structure.

Silicic acids may be formed by acidification of silicate salts (such as sodium silicate) in aqueous solution. When heated they lose water to form silica gel, an active form of silicon dioxide.

In the oceans, silicon exists primarily as orthosilicic acid (H4SiO4), and its biogeochemical cycle is regulated by the group of algae known as the diatoms.[3][4] These algae polymerise the silicic acid to so-called biogenic silica, used to construct their cell walls (called frustules).

Continuing research of the correlation of aluminium and Alzheimer's disease has in the last few years included the use of silicic acid in beverages,[5][6][7] due to its abilities to both reduce aluminium uptake in the digestive system as well as cause renal excretion of aluminium.

Orthosilicic acid is the form predominantly absorbed by humans and is found in numerous tissues including bone, tendons, aorta, liver and kidney. Compelling data suggest that silica is essential for health although no RDI has been established. However, deficiency induces deformities in skull and peripheral bones, poorly formed joints, reduced contents of cartilage, collagen, and disruption of mineral balance in the femur and vertebrae. [8] Study has shown that physiological concentration of orthosilicic acid stimulates collagen type 1 synthesis and osteoblastic differentiation in human osteoblast-like cells in vitro.[9]

Choline-stabilized orthosilicic acid is a bioavailable nutritional supplement. It has been shown to prevent the loss of hair tensile strength,[10] have positive effect on skin surface and skin mechanical properties, and on brittleness of hair and nails,[11] abate brittle nail syndrome,[12] partially prevent femoral bone loss in the aged ovariectomized rat model,[13] increase collagen concentration in calves ,[14] and have potential beneficial effect on bone collagen formation in osteopenic females.[15]


  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. ^ 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.
  4. ^ Treguer, P., Nelson, D. M., Van Bennekom, A. J., DeMaster, D. J., Leynaert, A. and Queguiner, B. (1995). The silica balance in the world ocean: A reestimate. Science 268, 375-379.
  5. ^ Exley C, Korchazhkina O, Job D, Strekopytov S, Polwart A, Crome P (2006). "Non-invasive therapy to reduce the body burden of aluminium in Alzheimer's disease". J. Alzheimers Dis. 10 (1): 17–24; discussion 29–31. PMID 16988476. 
  6. ^ González-Muñoz MJ, Peña A, Meseguer I (2008). "Role of beer as a possible protective factor in preventing Alzheimer's disease". Food Chem. Toxicol. 46 (1): 49–56. doi:10.1016/j.fct.2007.06.036. PMID 17697731. 
  7. ^ Gonzalez-Muñoz MJ, Meseguer I, Sanchez-Reus MI et al. (2008). "Beer consumption reduces cerebral oxidation caused by aluminum toxicity by normalizing gene expression of tumor necrotic factor alpha and several antioxidant enzymes". Food Chem. Toxicol. 46 (3): 1111–8. doi:10.1016/j.fct.2007.11.006. PMID 18096288. 
  8. ^ Martin KR (2007). "The chemistry of silica and its potential health benefits". J Nutr Health Aging 11 (2): 94–7. PMID 17435951. 
  9. ^ Reffitt DM, Ogston N, Jugdaohsingh R et al. (2003). "Orthosilicic acid stimulates collagen type 1 synthesis and osteoblastic differentiation in human osteoblast-like cells in vitro". Bone 32 (2): 127–35. doi:10.1016/S8756-3282(02)00950-X. PMID 12633784. 
  10. ^ Wickett RR, Kossmann E, Barel A et al. (2007). "Effect of oral intake of choline-stabilized orthosilicic acid on hair tensile strength and morphology in women with fine hair". Arch. Dermatol. Res. 299 (10): 499–505. doi:10.1007/s00403-007-0796-z. PMID 17960402. 
  11. ^ Barel A, Calomme M, Timchenko A et al. (2005). "Effect of oral intake of choline-stabilized orthosilicic acid on skin, nails and hair in women with photodamaged skin". Arch. Dermatol. Res. 297 (4): 147–53. doi:10.1007/s00403-005-0584-6. PMID 16205932. 
  12. ^ Scheinfeld N, Dahdah MJ, Scher R (2007). "Vitamins and minerals: their role in nail health and disease". J Drugs Dermatol 6 (8): 782–7. PMID 17763607. 
  13. ^ Calomme M, Geusens P, Demeester N et al. (2006). "Partial prevention of long-term femoral bone loss in aged ovariectomized rats supplemented with choline-stabilized orthosilicic acid". Calcif. Tissue Int. 78 (4): 227–32. doi:10.1007/s00223-005-0288-0. PMID 16604283. 
  14. ^ Calomme MR, Vanden Berghe DA (1997). "Supplementation of calves with stabilized orthosilicic acid. Effect on the Si, Ca, Mg, and P concentrations in serum and the collagen concentration in skin and cartilage". Biol Trace Elem Res 56 (2): 153–65. doi:10.1007/BF02785389. PMID 9164661. 
  15. ^ Spector TD, Calomme MR, Anderson SH et al. (2008). "Choline-stabilized orthosilicic acid supplementation as an adjunct to Calcium/Vitamin D3 stimulates markers of bone formation in osteopenic females: a randomized, placebo-controlled trial". BMC Musculoskelet Disord 9: 85. doi:10.1186/1471-2474-9-85. PMC 2442067. PMID 18547426. 

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Look at other dictionaries:

  • Silicic acid — Silicic Si*lic ic, a. [L. silex, silicis, a flint: cf. F. silicique.] (Chem.) Pertaining to, derived from, or resembling, silica; specifically, designating compounds of silicon; as, silicic acid. [1913 Webster] {Silicic acid} (Chem.), an… …   The Collaborative International Dictionary of English

  • silicic acid — n. 1. any of several jellylike masses, SiO2·n H2O, precipitated by acidifying sodium silicate solution 2. any of several hypothetical acids of which the different mineral silicates may be regarded as salts …   English World dictionary

  • silicic acid — Chem. any of certain amorphous gelatinous masses, formed when alkaline silicates are treated with acids, which dissociate readily into silica and water. [1810 20] * * * ▪ chemical compound       a compound of silicon, oxygen, and hydrogen,… …   Universalium

  • silicic acid — Obtained in water as a colloid by treating silicates; precipitated s. is silica gel. * * * silicic acid n any of various weakly acid substances obtained as gelatinous masses by treating silicates with acids * * * si·lic·ic ac·id (sĭ likґik)… …   Medical dictionary

  • silicic acid — noun Date: 1817 any of various weakly acid substances obtained as gelatinous masses by treating silicates with acids …   New Collegiate Dictionary

  • silicic acid —    H4SiO4 monomeric acid [16] …   Lexicon of Cave and Karst Terminology

  • silicic acid — noun a jellylike substance (hydrated silica) • Hypernyms: ↑acid …   Useful english dictionary

  • silicic acid — noun any of a range of compounds, being hydrates of silica; they form silicates having complex polymeric structures …   Wiktionary

  • silicic acid — noun Chemistry a hydrated form of silica made by acidifying solutions of silicates …   English new terms dictionary

  • silicic acid — See silex …   New dictionary of synonyms

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