N,N,N′,N′-Tetramethylazodicarbonxamide

Tsunoda, Tetsuto; Kaku, Hiroto

doi:10.1002/047084289x.rn00274

Cited by 3 publications

(3 citation statements)

References 38 publications

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“…The lower electronegativity of the nitrogen atoms in the À NR 2 groups in relation to the oxygen atoms in the À OR groups causes the former to be less electron withdrawing than the alkoxy groups. [41] Initially, we tried to find a breakthrough point for the etherification under Mitsunobu conditions by changing only the azo compound. Therefore, the reactions were carried out in the PPh 3 /ADDP redox system in various solvents (THF, toluene, DMSO/toluene, DMSO/benzene, 1,4-dioxane) at different temperatures.…”

Section: Resultsmentioning

confidence: 99%

Facile Synthesis of Hydroquinone Linked 3,3’‐Steroid Dimers via a Modified Mitsunobu Protocol

Klochowicz,

Morzycki,

Ramírez‐Lozano

et al. 2024

Eur J Org Chem

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Section: Resultsmentioning

confidence: 99%

Facile Synthesis of Hydroquinone Linked 3,3’‐Steroid Dimers via a Modified Mitsunobu Protocol

Klochowicz,

Morzycki,

Ramírez‐Lozano

et al. 2024

Eur J Org Chem

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“…[8][9][10][11] As argilas organofílicas são usualmente caracterizadas por difração de raios X, pois esta técnica permite, a partir do difratograma, calcular a distância interplanar basal; por espectroscopia na região do infravermelho com transformada de Fourier, em que determinadas bandas de absorção indicam a presença do surfactante e a medida de área específica para avaliar transformações estruturais ocorridas nos processos de modificação. 12 O fato da argila organofílica ser hidrofóbica e apresentar elevada área superficial específica, a torna interessante para diversas aplicações tecnológicas, como por exemplo, matéria-prima para diversos produtos (tintas, vernizes, graxas, resinas e cosméticos) 13 ena preparação de nanocompósitos poliméricos, [14][15][16][17] atuando na forma de agente de reforço 18 e de barreira a gases. 19,20 Na prática, tanto os surfactantes de sais de amônio quanto de fosfônio apresentam limitações.…”

Section: Introductionunclassified

Characterization of Sodium Bentonites: Effect of Treatment with Ammonium Salt-Free Organic Surfactant

Morita¹,

Barbosa²,

Kloss³

2015

Revista Virtual De Química

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Bentonites, which the main clay mineral is montmorillonite, are commercially attractive because of its abundance in nature. The clays can be modified by ion exchange reactions of ions contained in the interlayer region with cationic surfactants that include ammonium or phosphonium salts. The clays origin and the type of surfactants (modifiers) are the main factors in the alteration of physical and chemical properties of these materials. This study aims to characterize and compare the results of natural bentonites commercially available and the effect of treatments with quaternary ammonium salt and an organic compound free of ammonium salt. The FTIR and XRD results indicate the process of organophilization of clays after treatment with the surfactants. These treatments have altered the average particle size, suggesting the formation of agglomerates, which was showed in the SEM images. The results of surface area and particle size data indicated the presence of larger particles. Although the two surfactants have shown similarities in the investigated properties, the organoclays free of ammonium salt are more promising in terms of its use as well as for their preparation and solubility.Keywords: Bentonites; organoclays; surfactante. ResumoAs bentonitas, que tem como principal argilomineral a montmorilonita, são comercialmente atraentes devido sua abundância na natureza. Estas podem ser modificadas geralmente, através de reações de troca iônica dos íons contidos da região interlamelar com os surfactantes catiônicos, que incluem sais de amônio ou fosfônio. A origem das argilas e o tipo dos surfactantes (modificadores) são os principais fatores na alteração das propriedades físicas e químicas destes materiais. Este estudo tem como objetivo caracterizar e comparar os resultados de bentonitas naturais, comercialmente disponíveis, e o efeito dos tratamentos utilizados com sal quaternário de amônio e um composto orgânico livre de sal de amônio. Os resultados de FTIR e DRX indicam o processo de organofilização das argilas naturais após o tratamento com os surfactantes. Estes tratamentos alteraram o tamanho médio das partículas, sugerindo a formação de aglomerados, fato observado nas imagens de MEV. Os resultados das áreas superficiais e os dados de granulometria indicaram a presença de partículas de maior tamanho. Embora os dois surfactantes tenham apresentado similaridades nas propriedades investigadas, as argilas organofílicas livre de sal de amônio são mais promissoras quanto sua utilização, quanto ao seu preparo e solubilidade.Palavras-chave: Bentonitas; argilas organofílicas; surfactantes.

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“…If HA has pK a of higher than 11, the yield of RA is considerably lower, and with HA having pK a of higher than 13, the desired reaction does not occur. In order to overcome the restriction of pK a and expand the versatility of the original Mitsunobu reaction, [3][4][5][6][7] stabilized trialkylphosphoranes such as (cyanomethylene)tributylphosphorane (CMBP) 8) and (cyanomethylene)trimethylphosphorane (CMMP) 9,10) have been developed to replace the DEAD-TPP system.…”

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Preparation of (Cyanomethylene)tributylphosphorane: A New Mitsunobu-Type Reagent

Izumi

Nishii

Ozaki

et al. 2005

CHEMICAL & PHARMACEUTICAL BULLETIN

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The Mitsunobu reaction is a well-established fundamental reaction and has been applied widely in organic synthesis. In the Mitsunobu reaction, a unique dehydration occurs between alcohols and various Brønsted-Lowry acids (HA) utilizing the combination of diethyl azodicarboxylate and triphenylphosphine ( Fig. 1). 1,2) However, the reaction has a serious limitation (so-called the restriction of pK a ); the acidic hydrogen in HA has to have pK a of less than 11 for the reaction to proceed satisfactorily. If HA has pK a of higher than 11, the yield of RA is considerably lower, and with HA having pK a of higher than 13, the desired reaction does not occur. In order to overcome the restriction of pK a and expand the versatility of the original Mitsunobu reaction, 3-7) stabilized trialkylphosphoranes such as (cyanomethylene)tributylphosphorane (CMBP) 8) and (cyanomethylene)trimethylphosphorane (CMMP) 9,10) have been developed to replace the DEAD-TPP system.It was noted that CMBP was the only reagent that can be effectively applied to the Mitsunobu reaction of N-nonsubstituted sulfonamides such as p-toluenesulfonamide (1) (Fig. 2). The sulfonamide was unfortunately converted to phosphine sulfonimide 3 without any desired N-alkylated product 2 when using the traditional reagent DEAD-TPP or new reagents (TMAD-PBu 3 , 7) CMMP, etc.). 11)Thus, CMBP can not only promote the reaction of nucleophiles with pK a of higher than 13, but can be also utilized for synthesis of primary amines via Mitsunobu alkylation of sulfonamides.CMBP is now commercially available. However, many inquiries about the stability and handling of CMBP have been received. The reason is that we have not reported the procedure for the preparation of CMBP in detail, yet. In this paper, we would like to describe the experimental details for the preparation of this reagent and some important findings related to the handling. Furthermore, it is important to establish a facile procedure for CMBP preparation without further purification, especially when the Mitsunobu reaction is to be carried out on a large scale.Preparation of CMBP via (Cyanomethyl)tributylphosphonium Chloride (4) CMBP could be synthesized in two steps starting from chloroacetonitrile (Fig. 3). As the first step, tributylphosphine reacted with chloroacetonitrile in nitromethane to afford phosphonium salts 4 as colorless needles in 91% yield. The process was highly exothermic, and the addition rate of chloroacetonitrile was adjusted to be maintained at below 50°C. Since the salts 4 were hygroscopic, quick operation and storage in a desiccator were needed to prevent moisture from condensing on the product. The salts 4 were converted to CMBP by treatment with 0.95 equivalent of n-butyllithium in hexane at 0°C. It is important to note that the yield of CMBP decreased dramatically, when excess base (Ͼ1.0 eq) was used. So, a fresh n-butyllithium solution, of which the concentration is determined by titration, should be used.Furthermore, the Mitsunobu reaction could not unfortunately proceed effective...

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N,N,N′,N′-Tetramethylazodicarbonxamide

Cited by 3 publications

References 38 publications

Facile Synthesis of Hydroquinone Linked 3,3’‐Steroid Dimers via a Modified Mitsunobu Protocol

Facile Synthesis of Hydroquinone Linked 3,3’‐Steroid Dimers via a Modified Mitsunobu Protocol

Characterization of Sodium Bentonites: Effect of Treatment with Ammonium Salt-Free Organic Surfactant

Preparation of (Cyanomethylene)tributylphosphorane: A New Mitsunobu-Type Reagent

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