Related Experiment Video
Updated: May 28, 2025

Synthesis of Soft Polysiloxane-urea Elastomers for Intraocular Lens Application
Published on: March 8, 2019
Aldehyde-Assisted Alkoxysilane Condensation to Form Siloxane Bond: A New Process for Curing Alkoxy-Functional
Sławomir Rubinsztajn1, Urszula Mizerska1, Jan Kurjata1
1Centre of Molecular and Macromolecular Studies of Polish Academy of Sciences, 90-363 Lodz, Poland.
Abstract:
The formation of the siloxane bond is one of the most important reactions used in silicone chemistry and technology. In this paper, a new process for the condensation of alkoxy-functional silanes to form a siloxane bond is presented. The new reaction is catalyzed by a Ge(II)+ complex stabilized by pentamethylcyclopentadiene with a weakly coordinated anion, tetrakis(pentafluorophenyl)borane. A mechanistic study of this new condensation process using model alkoxy-functional silanes and propionaldehyde is completed. It is established that the quantitative conversion of alkoxysilanes to the siloxane bond requires stoichiometric amounts of aldehyde. It is also found that paraldehyde can serve as a convenient, higher boiling source of acetaldehyde for the condensation of alkoxysilanes. The results obtained, supported by DFT calculations, allow for us to formulate the mechanism of this reaction.
More Related Videos
Related Concept Videos
C–C Bond Formation: Aldol Condensation Overview
Aldol Condensation vs Claisen Condensation
Acid-Catalyzed α-Halogenation of Aldehydes and Ketones
In the first step of the mechanism, the acid protonates the carbonyl oxygen resulting in a resonance-stabilized cation, which subsequently loses an α-hydrogen to form an enol tautomer. The C=C bond in an enol is highly nucleophilic because of the electron-donating nature of the –OH group. Consequently, the double bond attacks an electrophilic halogen to form a...
Preparation of Aldehydes and Ketones from Alcohols, Alkenes, and Alkynes
Oxidation of Alkenes: Syn Dihydroxylation with Osmium Tetraoxide
Preparation of Alcohols via Addition Reactions
The acid-catalyzed addition of water to the double bond of alkenes is a large-scale industrial method used to synthesize low-molecular-weight alcohols. An acidic atmosphere is required to allow the hydrogen in the water molecule to act as an electrophile and attack the double bond in an alkene. The addition of a proton to the double bond creates a carbocation intermediate. The proton preferentially bonds to the less substituted end of the double bond to create a more stable carbocation...

