Photochemical processing taking place
in atmospheric aqueous phases
serves as both a source and a sink of organic compounds. In aqueous
environments, acid–base chemistry and, by extension, aqueous-phase
pH, are an important yet often neglected factors to consider when
investigating the kinetics of organic compounds. We have investigated
the aqueous-phase OH-oxidation of pinic acid, cis-pinonic acid, limononic acid, and formic acid (FA) as a function
of pH. We have also extended our studies to other organic acids (OAs)
present in the water-soluble fraction of secondary organic aerosol
(SOA) arising from the ozonolysis of α-pinene. Although all
the OAs exhibited larger OH reactivities at pH 10, the pH dependence
was dramatically different between FA, the smallest OA, and those
that contained more than eight carbons. A kinetic box model was also
employed to characterize our photoreactor and to provide confidence
to our results. Our finding shows that the atmospheric lifetimes of
small OAs (e.g., FA) are highly sensitive to cloud water pH. However,
those of larger OAs and many other OAs in α-pinene SOA are affected
to a much less extent. These results are of great importance for the
simplification of cloud water chemistry models.
Stereospecific nickel-catalyzed cross-coupling reactions of benzylic 2-methoxyethyl ethers are reported for the preparation of enantioenriched 1,1-diarylethanes. The 2-methoxyethyl ether serves as a traceless directing group that accelerates cross-coupling. Chelation of magnesium ions is proposed to activate the benzylic C-O bond for oxidative addition.
Atmospheric aqueous phases (cloud and fog droplets, aerosol liquid water) are important reaction media for the processing of water-soluble organic acids (OAs). The photochemistry of these species is known to...
The design and synthesis of a fluorescent sensor of diphosphate esters along with its application for in-gel detection is described. Dinuclear zinc complex 1 selectively binds diphosphate esters in the presence of various other functional groups, including monophosphate esters. Complex 1 also constitutes a competent stain for visualization of pyrophosphorylated proteins in polyacrylamide gels. This reagent will facilitate the validation and exploration of protein pyrophosphorylation.
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