The Reactivity of Oxygen-Containing Compounds in Their Oxidation

Oxidative degradation of poly(3-hydroxybutyrate). A new method of synthesis for the malic acid copolymers

“…According to the literature data esters undergo oxidation according to the free-radical chain mechanism and the a-C-H bond in alkoxy part of ester readily undergoes the reaction. 33 The products of ester oxidation are usually acids, aldehydes and/or ketones. In case of poly(3-hydroxybutyrate) oxidation can take place in methylene as well as methine group but methine group should be oxidized easier.…”

“…In case of poly(3-hydroxybutyrate) oxidation can take place in methylene as well as methine group but methine group should be oxidized easier. 33 Two main paths resulting in products identied in the PHB oxidized with ozone are Fig. 3 The ESI-MS 2 spectrum of ion m/z 623.6 (negative ion mode) with proposed structures of oligomers; molecules with a-mM end groups are omitted for simplification.…”

“…Unexpected result of PHB oxidation with oxygen/ozone mixture in 140 C was identication of the 3-malic-acidorigin units in the obtained polymer backbone. Such groups can be generated only via oxidation of methyl group of 3hydroxybutyrate repeating units, i.e., in the less probable oxidation path, albeit in literature there are examples of oxidation of methyl group in esters 33 or methyl group adjacent to methine one, e.g., in oxidation of i-propyl acetate in presence of hydroxyl radical. 43 Taking into account this data it was proposed that in the rst step the abstraction of hydrogen from methyl group by ROOc or cOH radical with generation of radical at methyl group 14 (ref.…”

“…On the other hand, it is known esters can undergo oxidation according to free-radical chain mechanism (Scheme 1). 33 The reaction takes place in alkoxy and/or acyl fragment of the ester, however the highest reactivity was reported for a-C-H bond in ester alkoxy group with formation of acids, ketones and/or aldehydes. Simplied mechanism of methyl ester oxidation is shown in the Scheme 1.…”

“…The structure of nal products depends on structure of the initial ester as well as position of the oxidized carbon. 33 The aim of this work was investigation of PHB oxidative degradation and possibility of applying the process to obtain new "green" material in one step. At rst, the possibility of degradation of natural PHB in oxidative conditions was investigated.…”