Silica sulfuric acid (-, SSA), a
solid acid
Solid is one of the four fundamental states of matter (the others being liquid, gas, and plasma). The molecules in a solid are closely packed together and contain the least amount of kinetic energy. A solid is characterized by structural ...
, is prepared by soaking
silica gel
Silica gel is an amorphous and porous form of silicon dioxide (silica), consisting of an irregular tridimensional framework of alternating silicon and oxygen atoms with nanometer-scale voids and pores. The voids may contain water or some other l ...
with
sulfuric acid.
SSA is used as a catalyst in different organic synthesis process.
Silica sulfuric acid is considered as cheap, nonhazardous and easy to handle
solid acid catalyst
In acid catalysis and base catalysis, a chemical reaction is catalyzed by an acid or a base. By Brønsted–Lowry acid–base theory, the acid is the proton (hydrogen ion, H+) donor and the base is the proton acceptor. Typical reactions catalyze ...
with high acidity.
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).
[{{Cite journal, last=Manna, first=Joydev, last2=Roy, first2=Binayak, last3=Sharma, first3=Pratibha, date=2015-02-01, title=Efficient hydrogen generation from sodium borohydride hydrolysis using silica sulfuric acid catalyst, journal=Journal of Power Sources, volume=275, pages=727–733, doi=10.1016/j.jpowsour.2014.11.040, bibcode=2015JPS...275..727M]
:SiO
2–H
2O + H
2SO
4 → SiO
2–H
2SO
4 + H
2O
Use
Silica sulfuric acid is mostly used as a solid acid catalyst in organic conversion.
References
Mineral acids
Sulfates
Sulfur oxoacids
Acid catalysts