Silanol is a compoud with Si-OH as functional group. It is similar to alcohol with the hydroxyl functionality (C-OH). Silanols are commonly used as intermediates in silicone chemistry and silicate mineralogy. If the silanol contains one or more organic residues, it is an organosilanol.
Applications
Analytical chemistry: Silanols can also be applied in analytical chemistry, such as chemical amplification systems. The system consists of radiation-induced acid generator, novolak matrix resin and silanol compound. The silanol compound shows a chemical affinity to aqueous alkali solution and can act as a dissolution promoter in an aqueous alkaline developer. Chemically amplified negative-resist systems utilizing acid-catalyzed silanol condensation reactions exhibit high sensitivity and high resolution for electron-beam and deep-ultraviolet exposure. Tradiation-induced acid-catalyzed silanol condensation produces siloxane oligomers in a novolak resin matrix, and the orientation or position of the siloxane structure effectively reduces the dissolution rate of the matrix.
Organic chemistry: Di-tert-butylsilanol can be used as an effective directing group for the palladium-catalyzed ortho-alkenylation of phenols. This method can be widely applied in organic synthesis because it can be easily removed under mild conditions. The synthetic usefulness of this alkenylation method is further demonstrated in the efficient synthesis of benzofuranone and alkenylated estrone derivatives. At the same time, the corresponding silanols undergo a smooth alkenylation/desilylation reaction, yielding a single regioisomer-olefinated estrone with a yield of 89%. This example shows complex phenol-containing bioactive molecules can be synthesized to promote diversity-oriented drug discovery by using silanol as starting material.
Physical chemistry: Single silanols and geminal silanols can be used in α-cristobalite models. When the surface segments intersect with each other in a particular case, the single silanols and geminal silanols at the intersection can have hydrogen bond to one another. The generalized α-cristobalite model can easily explain the reversible dehydration/rehydration behavior of silica below 400 °C. The generalized α-cristobalite model also closely matches the extensive experimental results obtained by various authors and through various technologies.
Figure 1. Pd-catalyzed o-alkenylation of phenols
Figure 2. The cristobalite crystal structure according to Wells
References
- Huang C, Chattopadhyay B, Gevorgyan V. Silanol: A traceless directing group for Pd-catalyzed o-alkenylation of phenols[J]. Journal of the American Chemical Society, 2011, 133(32): 12406-12409.
- Chuang I S, Maciel G E. A detailed model of local structure and silanol hydrogen bonding of silica gel surfaces[J]. The Journal of Physical Chemistry B, 1997, 101(16): 3052-3064.
