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1.
Org Biomol Chem ; 21(42): 8426-8462, 2023 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-37831479

RESUMO

Transition metal-catalyzed C-N bond formation reactions have gained popularity as a method for selectively transforming common C-H bonds into N-functionalized molecules. This approach is particularly useful for synthesizing aminated molecules, which require aminating reagents and amidated building blocks. Over the past two decades, significant advancements have been achieved in transition-metal-catalyzed C-H functionalization, with organic azides emerging as promising amino sources and internal oxidants. This review focuses on recent developments in utilizing sulfonyl and phosphoryl azides as building blocks for directed intra- and intermolecular C-H functionalization reactions. Specifically, it discusses methods for synthesizing sulfonamidates and phosphoramidates using sulfonyl and phosphoryl azides, respectively. The article highlights the potential of C-H functionalization reactions with organic azides for efficiently and sustainably synthesizing N-functionalized molecules, providing valuable insights into the latest advancements in this field.

2.
Bioresour Technol ; 96(17): 1889-96, 2005 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-16084368

RESUMO

A study was undertaken to examine the effect of temperature, moisture and storage time on the accumulation of free fatty acid in the rice bran. Rice bran stored at room temperature showed that most triacylglyceride was hydrolyzed and free fatty acid (FFA) content was raised up to 76% in six months. A two-step acid-catalyzed methanolysis process was employed for the efficient conversion of rice bran oil into fatty acid methyl ester (FAME). The first step was carried out at 60 degrees C. Depending on the initial FFA content of oil, 55-90% FAME content in the reaction product was obtained. More than 98% FFA and less than 35% of TG were reacted in 2 h. The organic phase of the first step reaction product was used as the substrate for a second acid-catalyzed methanolysis at 100 degrees C. By this two-step methanolysis reaction, more than 98% FAME in the product can be obtained in less than 8 h. Distillation of reaction product gave 99.8% FAME (biodiesel) with recovery of more than 96%. The residue contains enriched nutraceuticals such as gamma-oryzanol (16-18%), mixture of phytosterol, tocol and steryl ester (19-21%).


Assuntos
Gasolina , Óleos de Plantas/química , Ácidos/química , Catálise , Ácidos Graxos/análise , Hidrólise , Óleo de Farelo de Arroz , Temperatura , Fatores de Tempo , Água/análise
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