Ethanol—continued reactivity

Quininone, the most readily available member of the series, was used for the autoxidation studies. The Doering autoxidation procedure,4 that employs only tert-BuOH, was modified to include a THF tert-BuOH (4 1) mixture as the solvent. Likewise, the pressurized Parr bottle setup as described4 was replaced with a simple subsurface gas addition the solvent was presaturated with O2 gas, (compressed air could also be used as the O2 source) followed by t-BuOK addition and continued O2 gas purge. The autoxidations could likewise be conducted in the presence of ethanol or methanol, thereby producing the corresponding ethyl or methyl esters. Formation of these esters could occur via the reactive intermediate bicyclic lactam.4... 

Much is known about the biochemical toxicology of hepatotoxicants, yet much remains to be learned. Hepatotoxicity resulting in either cell necrosis, fibrosis, or fatty infiltration is known to be a widespread phenomenon, potentially of importance to human health. It is caused by numerous drugs and environmental agents, and its incidence is expected to increase as confounding viral liver disease becomes more prevalent. Much is known about mechanisms based upon comprehensive studies with a few prototypical chemicals—namely, CCb, ethanol and acetaminophen—which support a convergence of varied primary effects on the ultimate failure of mitochondrial function and Ca2+ homeostasis. The extensive metabolic activity of the liver exposes its cells to a continuous flux of prooxidants. The importance of metabolic activation for the production of reactive metabolites is well-... 

Photolysis of [Rh(tfacac)3] (tfacac is the unsymmetrically substituted 1,1,1-trifluoromethyl-acac) reveals the existence of two photoinduced reaction paths the relative efficiency of the two paths is dramatically solvent dependent.1140 In cyclohexane, mer- cis isomerization is the only observed photoreaction, but if ethanol or 2-propanol is added to the solvent, the photoisomerization efficiency decreases, and photodecomposition occurs. The nature of the photodecomposition products is not specified, but the enhanced photoreactivity in the presence of tri(n-butyl)stannane, a hydrogen atom donor, and flash and continuous photolysis studies in mixed-solvent systems strongly implicate hydrogen atom abstraction from the solvent as a key step in the photodecomposition of wer-[Rh(tfacac)3] and suggests that the photo reactive states have considerable radical character .1140 Analysis of quantum efficiencies implies that at least two distinct photoproduced excited states must be involved. 

As ethanol and methanol are common laboratory solvents, their application in extraction and reaction chemistry is not be discussed at length here details on many procedures using these solvents can be found in chemistry textbooks and the primary literature. However, exciting new procedures using acid catalysis in aqueous ethanol for the esterification of platform molecules have recently been reported.This reaction also highlights the reactivity of alcohols, as ethanol is one of the substrates in the reaction (Figure 5.4). It is likely that ethanol and water will continue to play a prominent role as solvents in the new transformation chemistries being developed. 

In the photoinitiated polymerisation of Jl-vinylpyrrolidinone and N-vinylcaprolactam in dioxane and ethanol, the rate was higher in the latter solvent and monomerlO. This was attributed to the influence of the two additional methylene groups in the caprolactam ring which increases monomer reactivity. Other interesting effects have included the radiation dose on the photopolymerisation of diallyl oxydiethylene dicarbonate O. Here long lived radicals were produced which continue to react in the dark. The rate appears to fit a relaxation model that considers double bonds as traps with increasing lifetimes that are able to transfer to radical sites. 

This chapter summarized the fundamental aspects and recent advances in electrocatalysts for the oxidation reactions of methanol and ethanol occurring at fuel cell anodes. Pt-based electrocatalysts are still considered to be the most viable for the anodic reactions in acidic media. The major drawback, however, is the price and limited reserves of Pt. To lower the Pt loading, the core-shell structure comprising Pt shells is more beneficial than the alloy structure, since aU the Pt atoms on the nanoparticle surfaces can participate in the catalytic reactions (and those in cores do not) particularly, the Pt submonolayer/monolayer approach would be an ultimate measure to minimize the Pt content. The architectures in nanoscale also have a significant effect on the reactivity and durability [119, 120] and thus should be explored continuously in a future. As for the ethanol oxidation, Rh addition is shown to enhance the selectivity towards C-C bond splitting however, Rh is even more expensive than Pt, and thus, the Rh content has to be very low, or less expensive constituents replacing Rh are necessary to be found. 

Hydroxy- and 4-ethoxy-3,4-dihydro-3-phenyl-2(lH)-quinazolinones as well as their thione analogs exhibit pseudobasic properties and may easily be condensed with 0-, N-, and C-nucleophiles (CH acids) by elimination of water or ethanol. Reactions with 0-, N-, and doubly activated C-nucleophiles (e. g. acetylacetone) may be effected by simply heating the components, while with the less reactive C-nucleophiles (monoketones) HCl must be used as catalyst. - E 4-Ethoxy-3,4-dihydro-3-phenylquinazolin-2(lH)-one dissolved in refluxing acetone, treated with a little coned. HCl, and refluxing continued 1 hr. 4-acetonyl-3,4-dihydro-3-phenylquinazolin-2(lH)-one. Y 71%. F.e. s. K. Lempert and P. Gyulai, Tetrahedron 26, 3443 (1970). 

There are a eonsiderable number of processes in which ethyl lactate is produced by esterification until a certain amount of water is formed, equilibrium is reached and then ethyl lactate is purified by distillation or other methods. These processes require excess of ethanol to overcome the equihbrium limitations, achieve higher conversions, and, besides, the separation of flic products from the equilibrium mixture is technically difficult, because of mixture of products and unconverted reactants. These are high cost operations. In order to improve ethyl lactate production, an alternative to conventional method consist of combining a separation unit with reaction stage. In the hybrid processes, at least one of die products is continuously removed from the reaction medium so equihbrium is shifted to products formation according to Le Chatelier s principle. In this regard, some reactive separation processes studied for ethyl lactate production are presented below. 

Nucleophilic Reactions.—Nucleophilic substitution in the isothiazole nucleus, as well as a variety of nucleophilic ring fissions, continue to attract a good deal of attention. The methylsulphonyl group is particularly prone to nucleophilic replacement 3,5-bis(methylsulphonyl)isothiazole-4-carbo-nitrile, readily accessible from malononitrile and carbon disulphide, yields the 5-(substituted)amino-compounds on treatment with ammonia, amines, or hydrazine, and the 5-ethoxy-compound when treated with ethanol in the presence of sodium carbonate. The electron-attracting cyano-group appears to promote the nucleophilic displacement, since 3,5-bis(methyIsuIphonyl)-4-phenylisothiazole displays reduced reactivity. ... 

The use of a non-pervaporative extractor-type catalytic polymeric membrane reactor has been reported for light alcohol/acetic acid esterifications. A cross-linked poly(styrene sulfonic acid) (PSA)/PVA blend flat membrane was assembled in the reactor in a vertical configuration, separating two chambers. One of the chambers was loaded with an aqueous solution of ethanol and acetic acid, while the other chamber was filled with chlorobenzene. The esterification equilibrium is displaced to the product s side by the continuous extraction of the formed ester. In the esterifications of methanol, ethanol and n-propanol with acetic acid, the reactivity through the PSA/PVA membrane was higher than that with HCl as catalyst. In that of n-butanol with acetic acid, however, it was viceversa. 

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