Technological aspects of synthesis of poly(ethylene glycol) mono-1-propenyl ether monomers

For the first time, the technological aspects of the highly productive and selective synthesis of UV-reactive poly(ethylene glycol) mono-1-propenyl ether monomers was developed. The solvent-free isomerization of model commercial available 2-allyloxyethanol and allyloxypoly(ethylene glycol) derivatives, type Allyl–[OCH2CH2]n–OH, n = 1–5, into a 1-propenyl derivative under the homogeneous catalysis conditions using the ruthenium complexes were evaluated. The effect of a various reaction conditions (i.e. the concentration of [Ru] complex, the reaction temperature, reaction gas atmosphere) together with trace amounts of allyl hydroperoxides formed via autoxidation reaction of allyl substrates on the productivity of catalyst was examined in detail. Moreover, the significant role of the allyl substrate structures on the catalytic activity of ruthenium catalysts were also recognized. The optimal parameters of the scaled-up synthesis together with productivity of catalyst were first established.

Rapid formation of HOMs from gas-phase alpha-pinene ozonolysis

<p>Alpha-pinene is the largest globally emitted monoterpene. Its oxidation reaction with ozone leads to peroxy radicals (RO<sub>2</sub>) that can subsequently form highly oxygenated organic molecules (HOMs) through the process of autoxidation. HOMs are considered to play a critical role in the growth of early particles as they can have sufficiently low saturation vapor pressures.</p><p>Pseudo-unimolecular autoxidation reaction is generally thought to compete with bimolecular reactions of RO<sub>2</sub>in the atmosphere. While these bimolecular reactions could potentially lead to radical recycling, [1] they are generally thought to lead to the formation of non-reactive products. In order to compete with these bimolecular reactions, the unimolecular autoxidation reaction must be rapid, especially in high RO<sub>2</sub>/NO conditions.</p><p>The initial ozonolysis reaction of a-pinene leads to the first-generation RO<sub>2</sub>with the 6-member ring broken. Current knowledge dictates the perpetuation of the inner 4-member cylobutyl ring in the first-generation RO<sub>2</sub>. This ring has proven to be a hurdle for rapid unimolecular autoxidation reactions as the steric hindrance the ring affords leads to high barriers (and therefore slow reaction rates) for hydrogen-shift (H-shift) reactions central to autoxidation. [2]</p><p>In this work, we show that the ozonolysis of a-pinene could directly lead to the formation of a hitherto unexplored completely ring-opened RO<sub>2 </sub>product. This pathway is made feasible by considering the large amount of excess energy channeled into the rovibrational modes of the vinoxy product after ozonolysis. This leads to the opening of the cyclobutyl ring of a significant fraction of the “hot” vinoxy radicals under atmospheric conditions, as opposed to all of them adding an O<sub>2</sub>molecule as was previously thought. The breaking of the ring potentially leads to the formation of products with up to 8 oxygen atoms after a single hydrogen shift reaction following the formation of the vinoxy.</p><p> </p><p>[1] Iyer, S.; Reiman, H.; Møller, K. H.; Rissanen, M. P.; Kjaergaard, H. G.; Kurtén, T. Computational Investigation of RO<sub>2</sub>+ HO<sub>2</sub>and RO<sub>2</sub>+ RO<sub>2</sub>Reactions of Monoterpene Derived First-Generation Peroxy Radicals Leading to Radical Recycling. J. Phys. Chem. A<strong>2018</strong>, 49, 9542-9552.</p><p>[2] Kurtén, T.; Rissanen, M. P. Rissanen, Mackeprang, K.; Thornton, J. A.; Jørgensen, S.; Ehn, M.; Kjaergaard, H. G. Computational Study of Hydrogen Shifts and Ring-Opening Mechanisms in a-Pinene Ozonolysis Products. J. Phys. Chem. A<strong>2015</strong>, 119, 11366-11375.</p><p> </p>

Standardization and regulation of the rate of the superoxide-generating adrenaline autoxidation reaction used for evaluation of pro/antioxidant properties of various materials

The superoxide-generating reaction of adrenaline autoxidation is widely used for determination of the activity of superoxide dismutase and pro/antioxidant properties of various materials. There are two variants of the spectrophotometric registration of the products of this reaction. The first is based on registration of adrenochrome, as adrenaline autooxidation product at 347 nm; the second employs nitro blue tetrazolium (NBT) and registration of diformazan, a product of NBT reduction at 560 nm. In the present work, recommendations for the standardization of the reaction rate in both variants have been proposed. The main approach consists in the use of the pharmaceutical form of 0.1% adrenaline hydrochloride solution. Although each of two adrenaline preparations available in the Russian market has some features in kinetic behavior of its autooxidation; they are applicable in the superoxide generating system based on adrenaline autooxidation. Performing measurements at 560 nm, the reaction rate can be regulated by lowering the concentration of added adrenaline, whereas during spectrophotometric registration at 347 nm, this cannot be done. These features of adrenaline autoxidation may be due to the fact that the intrinsic multistage process of the conversion of adrenaline to adrenochrome, which is recorded at 347 nm, is coupled with the transition of electrons from adrenaline and intermediate products of its oxidation to oxygen, carbon dioxide, and carbonate bicarbonate ions, which is detected in the presence of added NBT.

Studies on the oxidation of 2,6-di-tert-butylphenol by molecular oxygen catalyzed by cobalt(II) tetraarylporphyrins bound to cationic latex

A cationic latex has been prepared by emulsion copolymerization of styrene and divinylbenzene with 2 mol.% of quaternary ammonium ion surfactant monomer. The catalytic activity of cobalt(II) sulfonated tetraarylporphrins 1-5 supported on the cationic latex 6 was investigated in the autoxidation of 2,6-di-tert-butylphenol in water. All colloidal catalysts showed good catalytic activity in the autoxidation of 2,6-di-tert-butylphenol. Reaction products were identified as 2,6-di-tert-butyl-1,4-benzoquinone and the oxidative coupling product as 3,3',5,5'-tetra-tert-butyl-4,4'-diphenoquinone. The rate of autoxidation reaction catalyzed by 5 supported on cationic latex was found to increase with increasing pH in the range 7.0-10.0. At constant concentration of cobalt(II) porphyrin 5 in the reaction mixture, the rate as a function of the weight of the latex showed a maximum. The rate of autoxidation increased with increasing partial pressure of dioxygen in the range between 0.2 and 1.0 atm. 5,10,15,20-tetrakis(2,4,6-trimethyl-3,5-disulfonatopheny)porphyrinatocobalt(II) bound to the cationic latex was found to be the most reactive catalyst and the latex supported 5,10,15,20-tetrakis(2,6-dichloro-3-sulfonatophenyl)porphyrinatocobalt(II) showed the highest stability.