Epoxides hydroxyls

We emphasize that the above results have been observed only in the oxidation of sulfides and phenols, reactions known to follow radical mechanisms. A thorough investigation of the catalytic potential of the materials in other oxidation reactions (epoxidation, hydroxylations, etc.) is warranted. 

The desire to minimize this competitive oligomerization has motivated research into alternative means to decrease the polydispersity and simultaneously increase the molecular weight of the seed-oil derived polyols. Recent patents [128, 129] investigate an approach previously demonstrated for the hydroformylated polyols [130-132], i.e., hydroxylation of the fatty acid alkyl ester followed by polymerization from a petrochemically derived initiator molecule. Inventors state that this approach provides an improvement over previous epoxidized/hydroxylated polyols by allowing better control of the molecular weight and the functionality of the polyol products. 

A well-controlled foaming study of epoxidized/hydroxylated triglyceride polyols in low-density slabstock grade foams was performed by Zhang et al. 

Authors carefully investigated the potential causes of an increase in compressive modulus, which had been previously reported for flexible slabstock foams prepared from the polyols of the study [166]. Flexible foams prepared from a standard formulation containing two different levels of the epoxidized/hydroxylated soybean... 

The homopolymerization reactions of impure TGDDM (MY720) in the presence and absence of a BF3 NH2C2H5 catalyst and, also, pure TGDDM were monitored by FTIR as a function of cure temperature from 177 to 300 °C. The intensities of the epoxide, hydroxyl, ether and carbonyl bands at 906, 3500, 1120 and 1720 cm-1 respectively were determined from spectral differences and are plotted as a function in cure conditions in Figs. 10,11,12 and 13 respectively. The 906,1120 and 1720 cm-1 band intensities were normalized to the 805 cm-1 band and the 3500 cm-1 to the 1615 cm 1 band. The 805 and 1615 cm-1 bands are associated with the phenyl group which is assumed to chemically unmodified during the homopolymerization reactions. 

Hence, the most plausible explanation of our FTIR observations of the simultaneous appearance of hydroxyl, carbonyl and ether groups upon TGDDM epoxide consumption is epoxide isomerization and/or oxidation followed by epoxide-hydroxyl chain extension reactions. 

Fig. 22a and b. (i) Epoxide-hydroxyl and (ii) secondary amine-epoxide reactions that form (a) inter-molecular crosslinks and (b) intramolecular rings... 

Epoxidation/hydroxylation Aldrin, benzo(a)pyrene, aflatoxin, bromobenzene... 

Epoxidation/hydroxylation Benzo(a)pyrene, 2-aminofluorene, phenylbutazone... 

Using measured conversion rates and the heat evolution data, it is possible to estimate the relative heats of reaction of the epoxide-primary amine and the epoxide-hydroxyl reactions, the major reactions in this system. This calculation requires reliable estimates of the rate of appearance of hydroxyl groups and the rate of disappearance of the epoxide groups at early stages of the cure, as measured by FT-IR spectroscopy. These measurements can be corroborated by N-15 nmr monitoring of the rate of formation of secondary amines. 

Cytochromes P450 (P450) form a large family of heme enzymes that catalyze a diversity of transformations including epoxidation, hydroxylation and heteroatom oxidation. The enzymes are involved in the metabohsm of many... 

Optical absorption measurements indicate that the band gap of graphite oxide is within 2.4. 3 eV [64]. A detailed calculation has been performed to understand the effect of functional group, such as epoxide, hydroxyl, carbonyl, and their concentration to the optical properties of GO [65]. Their calculations predict a strong blue shift of the tt + <7 plasmon peak when the concentration of epoxides and hydroxyl groups in GO vary from 25 % to 75 %, while the n plasmon is less sensitive. Carbonyl groups present in the GO plane will create holes, which cause a red shift. Carbonyl holes significantly decreases the optical gap and opens the band gap, and they are useful for developing opto-electronic applications. 

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