Beckmann rearrangement of oximes using pivaloyl chloride/DMF complex

Narahari, Srinivasa Reddy; Reguri, Buchi Reddy; Mukkanti, K.

doi:10.1016/j.tetlet.2011.07.045

Cited by 25 publications

(16 citation statements)

References 29 publications

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“…A new protocol for mild, efficient, and general conversion of ketoximes 50 to their corresponding amides 17 was developed by Narahari and co-workers in 2011 through a Beckmann rearrangement using an inexpensive and nontoxic reagent (pivaloyl chloride/DMF complex) in DMF as the solvent (Scheme 64). 163 Classical Beckmann rearrangements were generally performed in the presence of strongly acidic and dehydrating media at high temperatures 97,[164][165][166] while formation of a pivaloyl chloride/DMF complex in this method was achieved at room temperature without the use of acid.…”

Section: Dmf As a Reagentmentioning

confidence: 99%

Beyond a solvent: triple roles of dimethylformamide in organic chemistry

2018

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N,N-Dimethylformamide (DMF) is frequently used as an aprotic solvent in chemical transformations in laboratories of academia as well as in those of chemical industry. In the present review, we will reveal that DMF is actually something much more than a solvent. It is a unique chemical since, as well as being an effective polar aprotic solvent, it can play three other important roles in organic chemistry. It can be used as a reagent, a catalyst, and a stabilizer.

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Section: Dmf As a Reagentmentioning

confidence: 99%

Beyond a solvent: triple roles of dimethylformamide in organic chemistry

2018

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“…114-115 °C). 17 Uma pequena amostra da acetanilida foi recristalizada em água, fornecendo um material mais cristalino (p.f. 113-114 °C).…”

Section: Aula 1: Síntese Da Acetanilida (1)unclassified

Síntese de cristais líquidos derivados do nitroazobenzeno: uma proposta de síntese multi-etapas aplicada às aulas de química orgânica experimental

Cristiano¹,

Cabral²,

Aquino³

et al. 2014

Quím. Nova

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. We describe a synthetic route consisting of five steps from aniline to obtain liquid crystal compounds derived from nitroazobenzene. Syntheses were performed during the second half of the semester in organic chemistry laboratory classes. Students characterized the liquid crystal phase by the standard melting point techniques, differential scanning calorimetry and polarized optical microscopy. These experiments allow undergraduate students to explore fundamentally important reactions in Organic Chemistry, as well as modern concepts in Chemistry such as self-assembly and self-organization, nanostructured materials and molecular electronics.Keywords: liquid crystals; multistep synthesis; azo compounds. INTRODUÇÃOCristais líquidos (CLs) constituem importantes materiais eletrônicos moleculares, que combinam as propriedades de ordem do estado sólido e a fluidez do estado líquido.1-2 Esta combinação única de mobilidade molecular e anisotropia ótica, elétrica e magnética propicia aos CLs um vasto número de aplicações tecnológicas, destacando-se como componentes ativos em mostradores planos (Liquid Crystal Displays, LCDs) de celulares, tablets, laptops e outros dispositivos. As fases líquido-cristalinas, chamadas de mesofases, são fases condensadas exibidas por determinadas moléculas, que possuem anisotropia de forma (alongadas, achatadas, biaxiais, etc.), em temperaturas intermediárias à fase cristal e à fase líquida. Os CLs são divididos basicamente em duas classes: os termotrópicos, cuja unidade fundamental geradora da mesofase é a molécula, e como o nome sugere, suas propriedades dependem da temperatura; e os liotrópicos, onde a unidade fundamental geradora da mesofase é um agregado de moléculas em um solvente. Os CLs termotrópicos são comumente classificados de acordo com sua forma molecular, sendo os CLs calamíticos constituídos por moléculas alongadas em forma de bastão e os CLs discóticos com a forma de disco. Os CLs calamíticos, objeto deste trabalho de educação, exibem normalmente mesofases nemática e esméticas. Em termos de ordenamento molecular, a fase nemática (N), aproxima-se mais do estado líquido isotrópico (Iso) e é caracterizada por apresentar apenas ordem orientacional, onde o eixo mais longo das moléculas está alinhado em uma direção comum (Figura 1). Nas fases esméticas (Sm), além da ordem orientacional, as moléculas possuem algum grau de ordem posicional, arranjadas em camadas. Possuem interações laterais mais fortes e maior viscosidade quando comparadas com a mesofase N, aproximando-se estruturalmente mais do estado sólido, ou cristal (Cr). Essas mesofases Sm são designadas por letras (A, B, C... K) de acordo com o seu ordenamento molecular. As mais normalmente observadas em CLs são a SmA e SmC (Figura 1). Na fase SmA, as moléculas estão alinhadas perpendicularmente ao plano das camadas e, na SmC, o arranjo molecular é levemente inclinado em relação a este plano (Figura 1). 3Apesar de sua importância nas tecnologias atuais, bem como em Ciência básica, CLs são geralmente omitidos dos currículos de...

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“…The vapor‐phase rearrangement requires high reaction temperatures leading to decay in catalytic activity, decomposition of the oxime and poor yields as well as high operating costs, while the solid state reactions involve tedious workup and separation issues . Consequently, liquid‐phase catalytic Beckmann rearrangement has garnered significant attention because it is desirable to conduct the reaction under mild conditions, with good selectivity and industrial practicality . As a result, various homogeneous and heterogeneous catalysts were developed for carrying out the rearrangement in a suitable medium.…”

Section: Introductionmentioning

confidence: 99%

A Facile One‐Pot Transformation of Aromatic Aldehydes/Ketones to Amides: Fe₂O₃@SiO₂ as an Environmentally Benign Core‐Shell Catalyst

Jain

Samant

2018

ChemistrySelect

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A one‐pot conversion of aldehydes and ketones to amides via atom‐efficient Beckmann rearrangement over modified Fe2O3 (hematite) has been investigated. A series of core‐shell catalysts were prepared having Fe2O3 core and SiO2 shell by encapsulation of Fe2O3 with varying amounts of silica and characterized. Transmission electron microscopy (TEM) of catalysts showed that silica shell thickness increased from 10 nm to 39 nm, while inductively coupled plasma atomic emission spectroscopy (ICP‐AES) determined that percent composition of Fe2O3 correspondingly decreased from ∼83% to 59%. Due to silica encapsulation, leaching of the catalytic species was minimized from ∼20% for Fe‐0 (100% Fe2O3) down to ∼10% for Fe‐4 (59% Fe2O3, 41% SiO2). Among the catalysts, Fe‐2 (71.3% Fe2O3, 28.7% SiO2) showed the best catalytic response for amide formation under optimized reaction conditions. The Brunauer Emmett Teller (BET) surface area of Fe‐2 increased to 50 m2/g as compared to 34 m2/g of Fe‐0. Differential scanning calorimetry and thermogravimetric analysis (DSC‐TGA) found catalyst Fe‐2 to be stable till 600°C. The catalyst Fe‐2 could be reused five times with good yield of the amide and no loss in catalytic activity. Using optimized conditions, the one‐pot transformation of aldehydes to primary amides and ketones to secondary amides was efficiently carried out by the catalyst Fe‐2. Thus an inexpensive, reusable and environmentally benign solid acid core‐shell catalyst Fe2O3@SiO2 is proposed.

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Beckmann rearrangement of oximes using pivaloyl chloride/DMF complex

Cited by 25 publications

References 29 publications

Beyond a solvent: triple roles of dimethylformamide in organic chemistry

Beyond a solvent: triple roles of dimethylformamide in organic chemistry

Síntese de cristais líquidos derivados do nitroazobenzeno: uma proposta de síntese multi-etapas aplicada às aulas de química orgânica experimental

A Facile One‐Pot Transformation of Aromatic Aldehydes/Ketones to Amides: Fe₂O₃@SiO₂ as an Environmentally Benign Core‐Shell Catalyst

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Beckmann rearrangement of oximes using pivaloyl chloride/DMF complex

Cited by 25 publications

References 29 publications

Beyond a solvent: triple roles of dimethylformamide in organic chemistry

Beyond a solvent: triple roles of dimethylformamide in organic chemistry

Síntese de cristais líquidos derivados do nitroazobenzeno: uma proposta de síntese multi-etapas aplicada às aulas de química orgânica experimental

A Facile One‐Pot Transformation of Aromatic Aldehydes/Ketones to Amides: Fe2O3@SiO2 as an Environmentally Benign Core‐Shell Catalyst

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A Facile One‐Pot Transformation of Aromatic Aldehydes/Ketones to Amides: Fe₂O₃@SiO₂ as an Environmentally Benign Core‐Shell Catalyst