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Hydrolysis and condensation alkoxysilanes
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Hydrolysis and condensation alkoxysilanes
1). Hydrolysis of silyl ethers can occur without a catalyst, if the rest of the molecule is hydrophilic, e.g. poly(ethyleneoxy)-trimethoxylsilane. But even so, their hydrolysis demands high temperatures and long reaction times. 2) A silanol can react with a silyl ether without a catalyst. But the reaction time is more than a year, at room temperature. 3). Theoretically, a silanol can react with another silanol without a catalyst. But in practice, hydrolysis doesn’t occur due to the extremely drastic conditions that are needed. 4). The mechanism's representation is wrong. This happens sometimes in polymer chemistry textbooks and more rarely, in polymer chemistry articles. Anyway, water attacks on the silicon and methoxide is the leaving group, which further forms methanol by picking the hydrogen from the so formed, protonated silanol. 5). In a similar way, the silanol hydroxyl group attacks on the silicon atom of another silanol, forming a siloxane.
1). Hydrolysis of silyl ethers can occur without a catalyst, if the rest of the molecule is hydrophilic, e.g. poly(ethyleneoxy)-trimethoxylsilane. But even so, their hydrolysis demands high temperatures and long reaction times. 2) A silanol can react with a silyl ether without a catalyst. But the reaction time is more than a year, at room temperature. 3). Theoretically, a silanol can react with another silanol without a catalyst. But in practice, hydrolysis doesn’t occur due to the extremely drastic conditions that are needed. 4). The mechanism's representation is wrong. This happens sometimes in polymer chemistry textbooks and more rarely, in polymer chemistry articles. Anyway, water attacks on the silicon and methoxide is the leaving group, which further forms methanol by picking the hydrogen from the so formed, protonated silanol. 5). In a similar way, the silanol hydroxyl group attacks on the silicon atom of another silanol, forming a siloxane.
2) A silanol can react with a silyl ether without a catalyst. But the reaction time is more than a year, at room temperature.
3). Theoretically, a silanol can react with another silanol without a catalyst. But in practice, hydrolysis doesn’t occur due to the extremely drastic conditions that are needed.
4). The mechanism's representation is wrong. This happens sometimes in polymer chemistry textbooks and more rarely, in polymer chemistry articles.
Anyway, water attacks on the silicon and methoxide is the leaving group, which further forms methanol by picking the hydrogen from the so formed, protonated silanol.
5). In a similar way, the silanol hydroxyl group attacks on the silicon atom of another silanol, forming a siloxane.
2) A silanol can react with a silyl ether without a catalyst. But the reaction time is more than a year, at room temperature.
3). Theoretically, a silanol can react with another silanol without a catalyst. But in practice, hydrolysis doesn’t occur due to the extremely drastic conditions that are needed.
4). The mechanism's representation is wrong. This happens sometimes in polymer chemistry textbooks and more rarely, in polymer chemistry articles.
Anyway, water attacks on the silicon and methoxide is the leaving group, which further forms methanol by picking the hydrogen from the so formed, protonated silanol.
5). In a similar way, the silanol hydroxyl group attacks on the silicon atom of another silanol, forming a siloxane.
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It is been a while ago (better late than never they say haha), but thank you for your reply.
In the mean while, I ve found that it would be possible with transition metals as catalyst.
It is been a while ago (better late than never they say haha), but thank you for your reply.
In the mean while, I ve found that it would be possible with transition metals as catalyst.
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Salts and organometallic compounds of transition metals, are Lewis acids and thus, they behave as acidic catalysts.
Salts and organometallic compounds of transition metals, are Lewis acids and thus, they behave as acidic catalysts.
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