Silylation: Difference between revisions
CrafterNova (talk | contribs) No edit summary |
M97uzivatel (talk | contribs) No edit summary |
||
| Line 4: | Line 4: | ||
==Of organic compounds== |
==Of organic compounds== |
||
Alcohols, carboxylic acids, amines, thiols, and phosphates can be silylated. The process involves the replacement of a proton with a trialkylsilyl group, typically [[trimethylsilyl]] (-SiMe<sub>3</sub>). Generally the substrate is deprotonated with a suitable strong base followed by treatment with a [[silyl chloride]] (e.g. [[trimethylsilyl chloride]]). Often strong bases such [[butyl lithium]] or a [[Grignard reagent]] are used, as illustrated by the synthesis of a trimethyl[[silyl ether]]s as [[protecting group]]s from an alcohol: |
Alcohols, carboxylic acids, amines, thiols, and phosphates can be silylated. The process involves the replacement of a proton with a trialkylsilyl group, typically [[trimethylsilyl]] (-SiMe<sub>3</sub>). Generally the substrate is deprotonated with a suitable strong base followed by treatment with a [[silyl chloride]] (e.g. [[trimethylsilyl chloride]]). Often strong bases such [[butyl lithium]] or a [[Grignard reagent]] are used, as illustrated by the synthesis of a trimethyl[[silyl ether]]s as [[protecting group]]s from an alcohol: |
||
:ROH |
:ROH + BuLi → ROLi + BuH |
||
:ROLi |
:ROLi + Me<sub>3</sub>SiCl → ROSiMe<sub>3</sub> + LiCl |
||
[[Bis(trimethylsilyl)acetamide]] ("BSA", Me<sub>3</sub>SiNC(OSiMe<sub>3</sub>)Me is an efficient silylation agent used for the derivatisation of compounds. The reaction of BSA with alcohols gives the corresponding trimethyl[[silyl ether]], together with N-(trimethylsilyl)acetamide as a byproduct: |
[[Bis(trimethylsilyl)acetamide]] ("BSA", Me<sub>3</sub>SiNC(OSiMe<sub>3</sub>)Me is an efficient silylation agent used for the derivatisation of compounds. The reaction of BSA with alcohols gives the corresponding trimethyl[[silyl ether]], together with N-(trimethylsilyl)acetamide as a byproduct: |
||
:ROH |
:ROH + Me<sub>3</sub>SiNC(OSiMe<sub>3</sub>)Me → Me<sub>3</sub>SiN(H)C(O)Me + ROSiMe<sub>3</sub> |
||
:[[File:Structure of bis(trimethylsilyl)acetamide.png|220px|thumb|[[Bis(trimethylsilyl)acetamide]], a popular reagent for silylation |
:[[File:Structure of bis(trimethylsilyl)acetamide.png|220px|thumb|[[Bis(trimethylsilyl)acetamide]], a popular reagent for silylation]] |
||
The introduction of a silyl group(s) gives derivatives of enhanced volatility, making the derivatives suitable for analysis by [[gas chromatography]] and electron-impact [[mass spectrometry]] (EI-MS). For EI-MS, the silyl derivatives give more favorable diagnostic [[fragmentation pattern]]s of use in structure investigations, or characteristic ions of use in trace analyses employing selected ion monitoring and related techniques.<ref>http://www.sigmaaldrich.com/analytical-chromatography/analytical-reagents/derivatization-reagents/silylation.html</ref><ref>{{cite book |title=Handbook of Derivatives for Chromatography |edition=2nd|last=Blau |first=Karl |author2=J. M. Halket |year=1993 |publisher=[[John Wiley & Sons]] |isbn= 0-471-92699-X |url=http://eu.wiley.com/WileyCDA/WileyTitle/productCd-047192699X.html }}</ref> |
The introduction of a silyl group(s) gives derivatives of enhanced volatility, making the derivatives suitable for analysis by [[gas chromatography]] and electron-impact [[mass spectrometry]] (EI-MS). For EI-MS, the silyl derivatives give more favorable diagnostic [[fragmentation pattern]]s of use in structure investigations, or characteristic ions of use in trace analyses employing selected ion monitoring and related techniques.<ref>http://www.sigmaaldrich.com/analytical-chromatography/analytical-reagents/derivatization-reagents/silylation.html</ref><ref>{{cite book |title=Handbook of Derivatives for Chromatography |edition=2nd|last=Blau |first=Karl |author2=J. M. Halket |year=1993 |publisher=[[John Wiley & Sons]] |isbn= 0-471-92699-X |url=http://eu.wiley.com/WileyCDA/WileyTitle/productCd-047192699X.html }}</ref> |
||
| Line 34: | Line 34: | ||
[[Category:Chemical processes]] |
[[Category:Chemical processes]] |
||
[[Category:Organosilicon compounds]] |
[[Category:Organosilicon compounds]] |
||
{{chem-stub}} |
|||
Revision as of 17:11, 22 January 2022
 | This article needs additional citations for verification. (January 2022) |
Silylation is the introduction of one or more (usually) substituted silyl groups (R3Si) to a molecule. The process is the basis of organosilicon chemistry.
Of organic compounds
Alcohols, carboxylic acids, amines, thiols, and phosphates can be silylated. The process involves the replacement of a proton with a trialkylsilyl group, typically trimethylsilyl (-SiMe3). Generally the substrate is deprotonated with a suitable strong base followed by treatment with a silyl chloride (e.g. trimethylsilyl chloride). Often strong bases such butyl lithium or a Grignard reagent are used, as illustrated by the synthesis of a trimethylsilyl ethers as protecting groups from an alcohol:
- ROH + BuLi → ROLi + BuH
- ROLi + Me3SiCl → ROSiMe3 + LiCl
Bis(trimethylsilyl)acetamide ("BSA", Me3SiNC(OSiMe3)Me is an efficient silylation agent used for the derivatisation of compounds. The reaction of BSA with alcohols gives the corresponding trimethylsilyl ether, together with N-(trimethylsilyl)acetamide as a byproduct:
- ROH + Me3SiNC(OSiMe3)Me → Me3SiN(H)C(O)Me + ROSiMe3
Bis(trimethylsilyl)acetamide, a popular reagent for silylation
acetamide.png)
The introduction of a silyl group(s) gives derivatives of enhanced volatility, making the derivatives suitable for analysis by gas chromatography and electron-impact mass spectrometry (EI-MS). For EI-MS, the silyl derivatives give more favorable diagnostic fragmentation patterns of use in structure investigations, or characteristic ions of use in trace analyses employing selected ion monitoring and related techniques.[1][2]
Desilylation
Desilylation is the reverse of silylation: the silyl group is exchanged for a proton. Various fluoride salts (e.g. sodium, potassium, tetra-n-butylammonium fluorides) are popular for this purpose.[3][4]
- ROSiMe3 + F− + H2O → ROH + FSiMe3 + OH−
Of metals
Coordination complexes with silyl ligands are well known. An early example is CpFe(CO)2Si(CH3)3, prepared by a salt metathesis reaction from trimethylsilyl chloride and CpFe(CO)2Na. Typical routes include oxidative addition of Si-H bonds to low-valent metals. Metal silyl complexes are intermediates in hydrosilation, a process used to make organosilicon compounds on both laboratory and commercial scales.[5][6]
See also
References
- ^ http://www.sigmaaldrich.com/analytical-chromatography/analytical-reagents/derivatization-reagents/silylation.html
- ^ Blau, Karl; J. M. Halket (1993). Handbook of Derivatives for Chromatography (2nd ed.). John Wiley & Sons. ISBN 0-471-92699-X.
- ^ Mercedes Amat, Sabine Hadida, Swargam Sathyanarayana, and Joan Bosch "Regioselective Synthesis of 3-Substituted Indoles: 3-Ethylindole" Organic Syntheses 1997, volume 74, page 248. doi:10.15227/orgsyn.074.0248
- ^ Nina Gommermann and Paul Knochel "N,N-Dibenzyl-n-[1-cyclohexyl-3-(trimethylsilyl)-2-propynyl]-amine from Cyclohexanecarbaldehyde, Trimethylsilylacetylene and Dibenzylamine" Organic Syntheses 2007, vol. 84, page 1. doi:10.15227/orgsyn.084.0001
- ^ Moris S. Eisen "Transition-metal silyl complexes" in The Chemistry of Organic Silicon Compounds. Volume 2 Edited by Zvi Rappoport and Yitzhak Apeloig, 1998, John Wiley & Sons.
- ^ Corey, J. Y.; Braddock-Wilking, J., "Reactions of Hydrosilanes with Transition-Metal Complexes: Formation of Stable Transition-Metal Silyl Compounds", Chem. Rev. 1999, vol. 99, pp. 175-292.doi:10.1021/CR9701086