A química dos ésteres de fosfato

Domingos, Josiel B.; Longhinotti, Elisane; Machado, Vanderlei G.; Nome, Faruk

doi:10.1590/s0100-40422003000500019

Cited by 27 publications

(29 citation statements)

References 41 publications

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“…19 Candidatus accumulibacter phosphatis was identified by molecular techniques and assigned to a subclass of PAO that is involved in phosphorus removal on a laboratory scale, but it was never isolated in pure culture. 2 O is an insoluble phosphate that has received attention from microbiologists. This is probably because different types of bacteria produce this mineral under laboratory conditions, and also because of the relationship of this compound to kidney calculi and to urinary infections.…”

Section: Phosphate Accumulation In Organismsmentioning

confidence: 99%

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Biogenic Synthesis of Important Environmental Minerals: Magnesium Phosphate Compounds and Perspectives

Durán¹,

Fávaro²

2018

Quim. Nova

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Recebido em 18/12/2017; aceito em 22/01/2018; publicado na web em 22/02/2018The ecological processes in which metabolites with industrial or medical applications are produced are of great importance. Magnesium plays many important roles in environmental and medical applications. Phosphorus is obtained by mining. It is estimated to have a very limited half-life and expected to be depleted as a resource in 100 years. Its recovery by mining and subsequent marketing as phosphate has important environmental implications. These processes are part of an important recovery technology. Bacteria have contributed to the formation of minerals since the advent of life on Earth. Bacterial and/or fungal biomineralizations play a critical role in biogeochemical cycles. These processes have important technological and environmental applications. In many past publications dealing with bacterial and fungal recovery of phosphates as insoluble products, magnesium played an important role. This is a review of recent progress in the microbial recovery of biogenic magnesium phosphate compounds, their importance, and their roles in treatment of several human diseases.

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Section: Phosphate Accumulation In Organismsmentioning

confidence: 99%

“…On a practical scale, phosphate-containing products are mainly formed from phosphoric acid (H 3 PO 4 ). [2][3][4][5] Phosphate accumulates mainly as polyphosphate. Phosphoruscontaining storage compounds may be inorganic or organic.…”

Section: Introductionmentioning

confidence: 99%

Biogenic Synthesis of Important Environmental Minerals: Magnesium Phosphate Compounds and Perspectives

Durán¹,

Fávaro²

2018

Quim. Nova

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“…Porém, a aplicação de organolantanídeos como catalisadores na polimerização de olefinas é uma das aplicações mais recentes das terras raras como catalisadores [13][14][15][16][17] . 11,[20][21][22] .…”

Section: Esquemaunclassified

“…Com o desenvolvimento tecnológico as terras raras passaram a ganhar novos usos e, hoje em dia, o universo de suas aplicações é muito abrangente, sendo utilizadas como catalisadores, por exemplo, no tratamento de emissões automotivas e no craqueamento do petróleo; na fabricação de laseres e como materiais luminescentes, "fósforos" na fabricação de lâmpadas fluorescentes e tubos de raios catódicos de aparelhos de televisão, etc. 5,[10][11][12][13][14][15][16][17][18][19][20] . O interesse em aplicar as terras raras na investigação das propriedades e funções de sistemas bioquímicos e na determinação de substâncias biologicamente ativas tem aumentado.…”

Section: Introductionunclassified

Terras raras: aplicações industriais e biológicas

Martins¹,

Isolani²

2005

Quím. Nova

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Recebido em 30/1/04; aceito em 30/6/04; publicado na web em 5/11/04 RARE EARTHS: INDUSTRIAL AND BIOLOGICAL APPLICATIONS. The history of the rare earths is rich in innovation and these elements have been the object of study of a number of scientists. Rare earths are used practically in almost all aspects of life and these applications are due to their outstanding properties, mainly spectroscopic and magnetic. In industry, the applications of rare earths are many, such as in catalysis, phosphors, magnetism, glass and lasers. In biological systems, rare earths are used, for example, as luminescent probes in the investigation of binding sites in proteins, labels in immunoassays and in noninvasive tests.Keywords: rare earths; spectroscopy; medical applications. INTRODUÇÃOAs terras raras, para as quais se utiliza o símbolo Ln, correspondem aos elementos do lantânio (La, Z = 57) ao lutécio (Lu, Z = 71), entre os quais se incluem o ítrio (Y, Z = 39) e o escândio (Sc, Z = 21). Mas, segundo recomendações da IUPAC 1 , usam-se os termos lantanídeos para designar os elementos do La ao Lu e terras raras quando aos lantanídeos são incluídos o Sc e o Y.A expressão terras raras é imprópria para designar estes elementos, que receberam esta denominação porque foram inicialmente conhecidos em forma de seus óxidos, que se assemelham aos materiais conhecidos como terras. Além da expressão "terras" não ser apropriada à denominação de tais elementos, a expressão "raras" também não está de acordo, pois os lantanídeos são mais abundantes (com exceção do promécio que não ocorre na natureza) do que muitos outros elementos. Por exemplo, os elementos túlio (0,5 ppm) e lutécio (0,8 ppm) que são as terras raras menos abundantes na crosta terrestre, são mais abundantes que a prata (0,07 ppm) e o bismuto (0,008 ppm) 2,3 . O primeiro elemento das terras raras descoberto foi o cério, em 1751, pelo mineralogista suíço A. F. Cronstedt, quando obteve um mineral pesado, a cerita. Porém, existem controvérsias quanto a este fato e atribui-se o ano de 1787 como o início da história das terras raras, quando Carl Axel Arrhenius encontrou um mineral escuro, a iterbita (também conhecido como gadolinita), em uma pequena vila, Ytterby, próxima a Estocolmo 2 . Por constituírem uma família que apresenta propriedades físicas e químicas semelhantes, exigindo um trabalho imenso para separá-los com a obtenção de espécies relativamente puras, este grupo de elementos foi pouco explorado durante anos e somente em 1907 é que praticamente todas as terras raras naturais foram conhecidas 4-9 . A industrialização das terras raras teve início com a fabricação de camisas de lampiões. Com o passar do tempo suas propriedades foram tornando-se mais conhecidas e seus compostos passaram a ser mais utilizados, tais como na produção de "mischmetal" para pedras de isqueiro, baterias recarregáveis e aplicações metalúrgicas 5,10 . Com o desenvolvimento tecnológico as terras raras passaram a ganhar novos usos e, hoje em dia, o universo de suas aplicações é muito abrangente, sendo utiliz...

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“…[10][11][12] The development of such stable and highly reactive nucleophiles has a wide range of applications in chemical detoxification, e.g., where quantitative phosphate bond cleavage is the target. 13 Some researchers in this field have noted that α-nucleophiles, such as hydroxylamine, represent a new perspective, but a better understanding of the attacking nucleophilic atom is still to be gained and this has prompted extensive mechanistic studies of the reactions of α-nucleophiles with activated acyl derivatives [14][15][16][17][18][19][20] , phosphate esters [21][22][23][24][25][26][27][28][29] and amides [30][31][32][33] . Hydroxylamine is a single α-nucleophile, the neutral and anionic forms of which ensure high rates of acyl transfer over a wide pH range and no other known α-nucleophile can beat it on its very strong nucleophilicity.…”

Section: Introductionmentioning

confidence: 99%

On the mechanism of the reaction between aryl acetates and hydroxylamine

Mazera¹,

Gesser²,

Pliego³

2007

Arkivoc

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The reaction of aryl acetates and hydroxylamine produces O-acylhydroxylamine and Nacylhydroxylamine, the latter being essentially observed for good leaving group esters and the former for poor leaving esters. For both acylation reactions, kinetics studies suggested a tetrahedral intermediate intervention for nucleofuges in a pKa range of 1 to 9. Esters having leaving groups with a pKa value less than 7 react by a rate-determining step inferred to be the tetrahedral intermediate formation, while for esters having leaving groups with a pKa value equal to or higher than 7, the rate-limiting step has been proposed to be the tetrahedral intermediate decomposition. General bifunctional acid-base catalysis by a second hydroxylamine molecule was identified as one of the components of the reaction for the intermediate collapse to products in the poor leaving group ester

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A química dos ésteres de fosfato

Cited by 27 publications

References 41 publications

Biogenic Synthesis of Important Environmental Minerals: Magnesium Phosphate Compounds and Perspectives

Biogenic Synthesis of Important Environmental Minerals: Magnesium Phosphate Compounds and Perspectives

Terras raras: aplicações industriais e biológicas

On the mechanism of the reaction between aryl acetates and hydroxylamine

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