Organische Chemie

Allinger, Norman L.; Jongh, Don C. de; Johnson, Carl R.; LeBel, Norman A.; Stevens, Calvin L.; Cava, Michael P.

doi:10.1515/9783110829709

Cited by 84 publications

(98 citation statements)

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“…Nevertheless at pH 5.5 k off is certainly less than 5i10 −% s −" , and hence K d must be less than 0.1 mM. Like k obs for azide binding, k obs for formate binding varies with pH in a manner consistent with the rate of binding being mainly controlled by the concentration of formic acid ; the fit shown in Figure 3 (lower panel) (see the Experimental section for details) is constrained to the pK a of formic acid (3.77) [33].…”

Section: Formatementioning

confidence: 99%

Comparison of the ligand-binding properties of native and copper-less cytochromes bo from Escherichia coli

Moody

Mitchell

Jeal

et al. 1997

Biochemical Journal

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The binding of four anionic ligands, cyanide, fluoride, azide and formate, to cytochrome bo purified from Escherichia coli cells grown with a copper supplement (+Cu cyt.bo) is described. Membrane-bound cytochrome bo that lacks the copper component, CuB, of its active site can be prepared from cells grown under conditions where the availability of copper is limited by the presence of a CuI chelator, 2,2′-bicinchinonic acid. The ligand-binding properties of this copper-less enzyme (-Cu cyt.bo) are compared with those of +Cu cyt.bo. As judged from near-UV/visible spectroscopic changes, cyanide forms a low-spin complex with +Cu cyt.bo, whereas azide, fluoride and formate form high-spin complexes. The pH-dependences of binding suggest that for all four of these anionic ligands, both the rates of binding and the binding affinities are primarily dependent on the concentration of their protonated forms. -Cu cyt.bo, which shows less than 15% of the duroquinol oxidase activity of +Cu cyt.bo, binds cyanide, azide and fluoride, but with greatly decreased affinity (< 1/30, 1/2000 and 1/2500 respectively at pH 5.5 compared with +Cu cyt.bo). The complex of azide with -Cu cyt.bo still seems to be high-spin and azide binding to -Cu cyt.bo is still pH-dependent, although less so than azide binding to +Cu cyt.bo.

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Section: Formatementioning

confidence: 99%

Comparison of the ligand-binding properties of native and copper-less cytochromes bo from Escherichia coli

Moody

Mitchell

Jeal

et al. 1997

Biochemical Journal

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“…22 A formação da olefina contida no aduto de Knoevenagel é uma transformação comumente ensinada nos cursos básicos de química orgânica teórica, [23][24][25][26][27][28][29][30][31][32] mas raramente realizada em aulas experimentais, 33 em franco contraste com a sua aplicação em síntese orgânica. 34 O ácido de Meldrum é um derivado cíclico do ácido malônico, muito empregado em síntese orgânica, que é disponível comercialmente e também objeto de aula experimental de química orgânica.…”

Section: A Condensação De Knoevenagelunclassified

“…Nos procedimentos clássicos que empregam catá-lise básica, este mecanismo está bem estabelecido. [22][23][24][25][26][27][28][29][30][31][32] Nas reações de condensação de Knoevenagel do ácido de Meldrum em água, o ânion resultante da sua ionização é o nucleófilo, uma vez que o ácido de Meldrum se encontra parcialmente ionizado em água, pois seu pKa é 4,83 neste solvente (comparável ao do ácido acético, pKa 4,75). 42 Adicionalmente, o aldeído e sua forma protonada também devem ser levados em consideração, Esquema 4.…”

Section: Considerações Mecanísticasunclassified

Condensação de Knoevenagel de aldeídos aromáticos com o ácido de Meldrum em água: uma aula experimental de Química Orgânica Verde

Cunha¹,

Santana²

2012

Quím. Nova

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“…In practice, the rate constant for breaking the C-H bond is 3 to 8 times higher than that for breaking a C-D bond. 118 Another possibility is if products differ by their ground energy and the reaction is ruled by thermodynamics, but not by kinetics as for boron. In aqueous solution, two boron species are present, B(OH) 3 and the B(OH) 4 À anion.…”

Section: Mass Fractionation Effects and Isotopic Variationsmentioning

confidence: 99%

Inductively coupled plasma- and glow discharge plasma-sector field mass spectrometry : Part I. Tutorial: Fundamentals and instrumentation

Jakubowski

Prohaska

Rottmann

et al. 2011

J. Anal. At. Spectrom.

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The aim of this series of two reviews is to introduce the basic concepts of ICP and GD sector field instruments, to discuss their peculiarities and performance, to present selected analytical applications for demonstration of the 'state of the art' and, finally, to identify possible future trends and developments. Part I focuses on fundamentals, instrumentation and operation of instruments to give an overview of the capabilities of the actual commercially available instrumentation, whereas selected applications will be discussed in detail in part II.

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Organische Chemie

Cited by 84 publications

References 0 publications

Comparison of the ligand-binding properties of native and copper-less cytochromes bo from Escherichia coli

Comparison of the ligand-binding properties of native and copper-less cytochromes bo from Escherichia coli

Condensação de Knoevenagel de aldeídos aromáticos com o ácido de Meldrum em água: uma aula experimental de Química Orgânica Verde

Inductively coupled plasma- and glow discharge plasma-sector field mass spectrometry : Part I. Tutorial: Fundamentals and instrumentation

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