Acyloxysilanes

Yur'ev, Yu. K.; Belyakova, Z V

doi:10.1070/rc1960v029n07abeh001240

Cited by 10 publications

(12 citation statements)

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“…The ν(OSi−H), ν(CO) , ν(Si−O−C), and ν(Si−O) absorptions grow in at approximately the same rate (Figure ), with ν(Si−O) growing in faster than ν(Si−O−C) at longer times. This indicates some conversion of the molecular ester to surface oxide over time, which may occur by reaction with trace moisture or by production of an ester anhydride and Si−O−Si from adjacent ester sites . The partial conversion of Si ester to simple oxide can be seen in difference IR spectra taken after 1 and 30 min of reaction.…”

Section: Resultsmentioning

confidence: 96%

“…This indicates some conversion of the molecular ester to surface oxide over time, which may occur by reaction with trace moisture or by production of an ester anhydride and Si-O-Si from adjacent ester sites. 61 The partial conversion of Si ester to simple oxide can be seen in difference IR spectra taken after 1 and 30 min of reaction. In Figure 3, the difference spectrum taken 1 min into the reaction shows growth of a large absorption at 1160 cm -1 assigned to ν(Si-O-C) stretches and a smaller absorption around 1068 cm -1 assigned to a ν(Si-O) stretching mode.…”

Section: Resultsmentioning

confidence: 99%

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Light-Induced Reactions of Porous and Single-Crystal Si Surfaces with Carboxylic Acids

et al. 1996

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Light-induced reactions of Si surfaces with carboxylic acids to generate Si ester-modified surfaces are studied. The reaction proceeds by photoelectrochemical oxidation of porous or (100)-oriented single-crystal n-type Si in formic, acetic, or trifluoroacetic acid electrolyte solutions. The reaction products at the porous Si surface are identified by Fourier-transform infrared (FTIR) spectroscopy. Derivatization with esters reduces the photoluminescence intensity of porous Si. X-ray photoelectron spectroscopy (XPS) of derivatized single-crystal Si is used to confirm the compositional and bonding information and to demonstrate that the same chemistry occurs at a single-crystal Si surface. A mechanism is proposed in which illumination of reverse-biased Si removes electron density from the Si surface, rendering Si-Si bonds susceptible to nucleophilic attack by carboxylic acid. The reaction has a marked dependence on light intensity and the Si surface can be photopatterned by illumination through a mask during derivatization. Ester-patterned porous Si reacts with CH 3 (CH 2 ) 7 (CH 3 ) 2 SiOCH 3 , generating an organosilane-patterned Si surface.Chemical reactions at the surfaces of electronic materials can be very different from the corresponding solution-phase transformations. In particular, the electronic structure of a semiconductor provides a source of electrons or holes that can be used to induce a surface reaction. In this paper, we present a new reaction which modifies the H-terminated surface of porous and single-crystal n-type Si by photoelectrochemical reaction with carboxylic acids, producing a surface-bound silyl ester. The Si surface is activated toward photochemical reaction by applying a positive potential across n-type Si (the reverse-bias condition) in an electrochemical cell. This bends the conduction and valence bands of the Si such that, upon optical excitation, holes migrate to the surface (Scheme 1). Carboxylic acids attack the irradiated, electron-deficient surface, resulting in a surfacebound Si-ester species. Using this simple idea Si surfaces can be photolithographically patterned with esters.

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Section: Resultsmentioning

confidence: 96%

Section: Resultsmentioning

confidence: 99%

Light-Induced Reactions of Porous and Single-Crystal Si Surfaces with Carboxylic Acids

et al. 1996

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“…The overall synthetic route and reaction yields are summarized in the Scheme and Table , respectively. Two equivalents of the sodium alkoxide react with HFPO to yield the ester 5 , which is converted to the sodium carboxylate salt 6 and then to the trimethylsilyl ester 7 prior to thermolysis to the desired TFVE 8 . Conversion of the alkoxy ester to the trimethylsilyl ester is critical to the success of this synthesis as will be described.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of Trifluorovinyl Ethers Incorporating Functionalized Hydrocarbon Ether Groups: Insight into the Mechanism of Trifluorovinyl Ether Formation from Trimethylsilyl 2-Alkoxy-2,3,3,3-tetrafluoropropionates

Lousenberg

Shoichet

1997

J. Org. Chem.

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Novel trifluorovinyl ethers (TFVEs, ROCFdCF 2 ), where R is an oligoether, were synthesized from the corresponding sodium alkoxide and hexafluoropropene oxide. The sodium alkoxide ring opened hexafluoropropene oxide at the more highly substituted carbon (C2) to give the 2-alkoxy-2,3,3,3tetrafluoropropionic acid ester incorporating 2 equiv of the alcohol, ROCF(CF 3 )CO 2 R. Hydrolysis of the ester and reaction of the resulting sodium 2-alkoxy-2,3,3,3-tetrafluoropropionate with chlorotrimethylsilane gave the trimethylsilyl 2-alkoxy-2,3,3,3-tetrafluoropropionate, ROCF(CF 3 )CO 2 -Si(CH 3 ) 3 . Gas phase vacuum thermolysis of the trimethylsilyl ester at 140-150 °C gave the corresponding TFVEs in 55-63% yields. Thus, 1-[2-(ethoxyethoxy)ethoxy]-1,2,2-trifluoroethene and 1-[2-(2-tert-butoxyethoxy)ethoxy]-1,2,2-trifluoroethene were synthesized from 2-(2-ethoxyethoxy)ethanol and 2-(2-tert-butoxyethoxy)ethanol, respectively. Interestingly, thermolysis of sodium or potassium 2-alkoxy-2,3,3,3-tetrafluoropropionates resulted in negligible to low yields of TFVEs. 1 For example, thermolysis of sodium 2-[2-(ethoxyethoxy)ethoxy]-2,3,3,3-tetrafluoropropionate gave a trifluoroacetate ester, 2-(2-ethoxyethoxy)ethyl trifluoroacetate. Variable temperature 19 F NMR spectroscopy of trimethylsilyl 2-[2-(ethoxyethoxy)ethoxy]-2,3,3,3-tetrafluoropropionate suggests that an equilibrium exists between two structural conformations of these trimethylsilyl esters: one in which there is an intramolecular "interaction" of silicon with fluorine and one in which there is no silicon-fluorine interaction. This interaction may affect the outcome of the trimethylsilyl ester thermolysis.

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“…A silyl ester intermediate initially forms from the carboxylic acid and Me2SiCl2, and cyclization occurs from nucleophilic attack of the free amine at the carbonyl carbon to give 2. 1 H NMR experiments also supported the presence of the cyclic intermediate, though attempts to isolate the cyclic intermediate were unsuccessful. The authors investigated the regiochemistry of the method when two carboxylic acid functionalities are present in the amino acid.…”

Section: Amidation Using Chlorosilanesmentioning

confidence: 94%

Silyl Esters as Reactive Intermediates in Organic Synthesis

et al. 2023

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Silyl esters have been exploited as meta-stable reaction intermediates – both purposefully and unintentionally – since at least the 1960s. Their reactivity is broadly related to the substituents on the silicon, and in this way their properties can be readily modulated. Silyl esters have unique reactivity profiles that have been used to generate downstream products of a range of functionalities, and because of this many excellent methods for the synthesis of a variety of value-added chemicals have been developed. Furthermore, because of the frequent use of hydrosilanes as terminal reductants in catalytic processes, silyl ester intermediates are likely more commonly utilized by synthetic chemists than currently realized. This review comprehensively summarizes the reactions known to take advantage of reactive silyl ester intermediates and discusses examples of catalytic reactions that proceed in an unanticipated manner through silyl ester intermediates.

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Acyloxysilanes

Cited by 10 publications

References 0 publications

Light-Induced Reactions of Porous and Single-Crystal Si Surfaces with Carboxylic Acids

Light-Induced Reactions of Porous and Single-Crystal Si Surfaces with Carboxylic Acids

Synthesis of Trifluorovinyl Ethers Incorporating Functionalized Hydrocarbon Ether Groups: Insight into the Mechanism of Trifluorovinyl Ether Formation from Trimethylsilyl 2-Alkoxy-2,3,3,3-tetrafluoropropionates

Silyl Esters as Reactive Intermediates in Organic Synthesis

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