Our first question focused on whether it could be possible to activate the hemiacetal
For M19, the product ions m/z 144 and m/z 244 in the MS/MS spectrum suggest a carboxyl function at the defluorinated pentyl chain and further biotransformation at the TMCP ring, which probably is the formation of a hemiacetal
structure of a hydroxyl group at the 2' position and a reactive aldehyde group at the 3' position.
Seib, (1997) suggested that aldehyde groups initially generated by low levels of oxidant formed hemiacetal
cross links in oxidized starch, which stabilized the swelling of starch granules and also reduced its solubility as the crosslinks would prevent the amylopectin molecules from leaching out (Wang and Wang, 2003).
contains an asymmetric carbon atom and therefore can exist in two stereo isomeric form.
1973), quienes encontraron 3-hidroxi-2-formil benzotiofeno, 3-oxo-[3'-hidroxi-tionaftenil-(2)-metileno]-dihidrotionafteno y las formas hemiacetal
y trans del acido 4-[2-(3-hidroxi)-tianaptenil]-2-oxo-3-butenoico, los cuales son encontrados en la ruta metabolica de Kodoma.
This occurs through hemiacetal
linkages between hydroxyl groups of cellulose/hemicellulose and aldehyde groups formed at C6 primary hydroxyl groups of cellulose by the TEMPO-mediated oxidation.
All chemical reactions occur at hemiacetal
bond and/or hydroxyl groups, which determine chemical properties of cellulose.
In contrast, more than 99% of aldosterone cyclizes, with the alde- hyde group at carbon 18 reacting with the hydroxyl at carbon 11, forming a stable 11,18 hemiacetal
The P450-dependent hydroxylation of the methoxy group yields an intermediate corresponding to the hemiacetal
of formaldehyde that can cyclize to form a methylenedioxy bridge via an ionic mechanism involving the methylene oxonium ion intermediate.
The primary products from the methanolysis of CS and DS were presumed to be uronic or iduronic acid-N-acetylhexosamine dimers, methylated at both the carboxylic acid and terminal hemiacetal
In aqueous solution, they occur as an equilibrium of four related molecular structures; namely the fiavylium cation, quinoidal base, hemiacetal
and chalcone forms.