Silica sulfuric acid

Silica sulfuric acid (SiO
2-OSO
3H
2, SSA), a solid acid, is prepared by soaking silica gel with sulfuric acid.[1] SSA is used as a catalyst in different organic synthesis process.[2][3] Silica sulfuric acid is considered as cheap, nonhazardous and easy to handle solid acid catalyst with high acidity.[4]

Synthesis

In a typical process, SSA is prepared by soaking silica gel into sulfuric acid of an appropriate concentration. Then moisture and water content of the mixture was evaporated by heating at high temperature (120–180 °C).[1][5]

SiO2–OH2 + HO–SO3H → SiO2–OSO3H2 + H2O

Use

Silica sulfuric acid is mostly used as a solid acid catalyst in organic conversion.[2][3]

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gollark: Also the ether, which as far as I'm aware was obsoleted a hundred years ago by better theories.
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References
  1. Riego, Juan M; Sedin, Zeno; Zaldívar, JoséM; Marziano, Nunziata C; Tortato, Claudio (1996-01-22). "Sulfuric acid on silica-gel: an inexpensive catalyst for aromatic nitration". Tetrahedron Letters. 37 (4): 513–516. doi:10.1016/0040-4039(95)02174-4.
  2. Zolfigol, Mohammad Ali (2001-11-12). "Silica sulfuric acid/NaNO2 as a novel heterogeneous system for production of thionitrites and disulfides under mild conditions". Tetrahedron. 57 (46): 9509–9511. doi:10.1016/S0040-4020(01)00960-7.
  3. Salehi, Peyman; Dabiri, Minoo; Zolfigol, Mohammad Ali; Bodaghi Fard, Mohammad Ali (2003-03-31). "Silica sulfuric acid: an efficient and reusable catalyst for the one-pot synthesis of 3,4-dihydropyrimidin-2(1H)-ones". Tetrahedron Letters. 44 (14): 2889–2891. doi:10.1016/S0040-4039(03)00436-2.
  4. Sadeghi, Bahareh; Nejad, Mahboobeh Ghasemi (2012-07-19). "Silica Sulfuric Acid: An Eco-Friendly and Reusable Catalyst for Synthesis of Benzimidazole Derivatives". Journal of Chemistry. 2013: 1–5. doi:10.1155/2013/581465. ISSN 2090-9063.
  5. Manna, Joydev; Roy, Binayak; Sharma, Pratibha (2015-02-01). "Efficient hydrogen generation from sodium borohydride hydrolysis using silica sulfuric acid catalyst". Journal of Power Sources. 275: 727–733. Bibcode:2015JPS...275..727M. doi:10.1016/j.jpowsour.2014.11.040.
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