Hypervalent tellurium
compounds (telluranes) are promising therapeutical agents with negligible
toxicities for some diseases in animal models. The C–Te bond
of organotellurium compounds is commonly considered unstable, disfavoring
their applicability in biological studies. In this study, the stability
of a set of telluranes composed of an inorganic derivative and noncharged
and charged organic derivatives was monitored in aqueous media with
1
H,
13
C, and
125
Te NMR spectroscopy and
high-resolution mass spectrometry. Organic telluranes were found to
be remarkably resistant and stable to hydrolysis, whereas the inorganic
tellurane
AS101
is totally converted to the hydrolysis
product, trichlorooxytellurate, [
TeOCl
3
]
−
, which was also observed in the hydrolysis
of
TeCl
4
. The noteworthy stability
of organotelluranes in aqueous media makes them prone to further structure–activity
relationship studies and to be considered for broad biological investigations.
N-methyl-2-pyrrolidonium methyl sulfonate, a Brønsted acid ionic liquid, promoted the transesterification of soybean oil with ethanol giving a high quality fatty acid ethyl ester. At the end of the reaction, after distillation of excess of ethanol, spontaneous phase separation took place. While the clear upper phase corresponded to the ethyl ester, the lower phase was composed of a mixture of glycerol byproduct and the catalyst. By addition of a stoichiometric amount of appropriated reagents to the resulting mixture, a new ionic liquid-catalyzed process allows the conversion of the glycerol into less polar derivatives, and consequent migration to the ethyl esters phase. This work demonstrated that emulsion, phase separation and contamination problems were completely avoided and the glycerol could be incorporated into the biodiesel as additives in a single step. The whole process involves two renewable starting materials, ethanol and vegetable oil, allowing a total green additive-blended biodiesel production process.
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