Silica-supported orthophosphoric acid (OPA/SiO2): preparation, characterization, and evaluation as green reusable catalyst for pinacolic rearrangement

Billamboz, Muriel; Banaszak, Estelle

doi:10.1007/s13738-018-01582-2

Cited by 3 publications

(4 citation statements)

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“…As depicted in Figure b, the typical absorption vibration bands of the phosphoric groups were observed. The bands due to the stretching vibration were found at ∼1140 and ∼1010 cm –1 , bands for asymmetric vibrations at ∼933 and ∼722 cm –1 , and the band due to bending vibration at ∼473 cm –1 , while the absorption intensity of the IR spectra increased with increased heating temperature. ,− The vibration bands gradually shifted to higher wavenumbers with increased heating temperature, as denoted by the dashed lines in Figure b. This peak shift can be correlated with the conformational changes in the molecular structure of the phosphates by concentration.…”

Section: Resultsmentioning

confidence: 86%

“…Additionally, PA_200 enabled the dissolution of 7 wt % fumed silica, but the obtained solution became highly viscous and eventually transformed into a transparent solid at 80 °C within 5 h. It is reported in the literature that silica dissolution occurred through esterification with phosphoric acid. 26,27 However, in this study, it was difficult to prove the existence of P−O−Si bonding by 29 Si NMR and FT-IR spectroscopy. The limitation in the characterization is considered to originate from the low concentration of silica species in the mixture solution.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…25 The reaction leads to compounds containing silylphosphate species, and these are known as highly selective nitride (HSN). 26,27 As an additive, aliquots of HSN, comprising mostly commercial phosphoric acid (85%) and employed for selective Si 3 N 4 etching, ranging from 0.1 to 1 wt %, are typically added to the etchant.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Since the solubility of amorphous silica in an acidic aqueous solution is low and almost constant at ∼150 ppm at 25 °C, the silica species are separately prepared by a dissolving reaction of the silica precursor and phosphoric acid, and the etchant is added as an additive . The reaction leads to compounds containing silyl-phosphate species, and these are known as highly selective nitride (HSN). , As an additive, aliquots of HSN, comprising mostly commercial phosphoric acid (85%) and employed for selective Si 3 N 4 etching, ranging from 0.1 to 1 wt %, are typically added to the etchant.…”

Section: Introductionmentioning

confidence: 99%

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Green Manufacturing of Silyl-Phosphate for Use in 3D NAND Flash Memory Fabrication

Lee

Kim

Tikue

et al. 2021

ACS Sustainable Chem. Eng.

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Three-dimensional NAND flash memory featuring dozens of vertically stacked memory cells is the state-of-the-art technology for most storage platforms. To fabricate threedimensional (3D) NAND memory, lateral etching of the Si 3 N 4 layer over SiO 2 is an essential step that is conducted through a wet etching process using a phosphoric acid-based etchant. Silylphosphate or highly selective nitride serves as an etching solution additive to control the SiO 2 layer dissolution rate. However, silylphosphate is prepared with an expensive monomeric silica precursor and at high reaction temperatures and generates environmentally harmful byproduct gases, such as HCl, HF, and CH 3 OH. This study demonstrates that silyl-phosphate can be prepared using low-cost polymeric silica under a mild reaction temperature by changing the characteristic acidity of phosphoric acid. The possibility of tuning the phosphoric acid acidity was first studied by molecular dynamics simulations, and phosphoric acids with stronger acidity were prepared by the evaporation of water from H 3 PO 4 (85%). The concentrated phosphoric acid enabled a fast reaction of polymeric silica and phosphate at a low reaction temperature (80 °C). The obtained silyl-phosphate lowered the SiO 2 layer dissolution rate, thereby yielding a Si 3 N 4 /SiO 2 layer etching ratio of up to 940. The proposed method offers an environmentally friendly production process for special chemicals used in 3D NAND flash memory fabrication. KEYWORDS: 3D NAND, concentrated H 3 PO 4 , fumed silica, Si 3 N 4 layer, SiO 2 layer, wet etching

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Section: Resultsmentioning

confidence: 86%

Section: ■ Results and Discussionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Green Manufacturing of Silyl-Phosphate for Use in 3D NAND Flash Memory Fabrication

Lee

Kim

Tikue

et al. 2021

ACS Sustainable Chem. Eng.

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Silica-supported ionic liquid for efficient gaseous arsenic oxide removal through hydrogen bonding

Zhang,

Wang,

Xie

et al. 2024

Journal of Hazardous Materials

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Synthesis of Tetraphenyl-Furoindoles via Tandem Reactions

Jiang¹,

An²,

Zhang³

2021

HETEROCYCLES

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We report a novel one-step synthesis of tetraphenyl substituted furoindoles involving acid-catalyzed cascade approach of commercially available m-aminophenols with readily accessible α-hydroxyaldehydes. The tandem reactions involved nucleophilic addition, aldimine condensation, pinacol rearrangement, α-iminol rearrangement, cyclization and dehydration aromatization process. The yield of furoindoles was up to 75%.Tetraphenyl substituted furoindoles are crucial structural motifs in various organic materials. 1 As a result, the synthesis of these target molecules by feasible methodologies have great significance, and indeed, various synthetic routes have been used for the construction of tetraphenyl substituted furoindoles and their derivatives. Some of synthetic strategies toward tetraphenyl substituted furoindoles are shown in Scheme 1. The classic method for the synthesis of tetraphenyl substituted furoindoles involves Pd catalyzed condensation of halogenated arenes with phenylacetylene (path a, Scheme 1). 1b Unfortunately, this method needs 4 steps to give access to tetraphenyl substituted furoindoles. Another method only needs two steps to give access to tetraphenyl substituted furoindoles, but this approcach needs special phosphorus ligand (path b and c Scheme 1). 1c,1f In 2018, Yan group introduced one approach for the p-toluenesulfonic acid (PTSA) catalyzed synthesis of tetraphenyl substituted furoindoles. The yield of this approcach can only reach to 35% showing only one example (path d, Scheme 1). 1e Sahoo developed a novel synthesis of tetraphenyl substituted furoindoles involving Pd and Rh catalyzed oxidative annulations of both commercially available phenols with 1,2-diphenylethyne. This method can synthesize two types of tetraphenyl substituted furoindoles. The yield can reach to 36% (over 2 steps) and 29% (over

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Silica-supported orthophosphoric acid (OPA/SiO2): preparation, characterization, and evaluation as green reusable catalyst for pinacolic rearrangement

Cited by 3 publications

References 64 publications

Green Manufacturing of Silyl-Phosphate for Use in 3D NAND Flash Memory Fabrication

Green Manufacturing of Silyl-Phosphate for Use in 3D NAND Flash Memory Fabrication

Silica-supported ionic liquid for efficient gaseous arsenic oxide removal through hydrogen bonding

Synthesis of Tetraphenyl-Furoindoles via Tandem Reactions

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