Ethanol, from oxidation

Alcoholism leads to fat accumulation in the liver, hyperlipidemia, and ultimately cirrhosis. The exact mechanism of action of ethanol in the long term is stiU uncertain. Ethanol consumption over a long period leads to the accumulation of fatty acids in the liver that are derived from endogenous synthesis rather than from increased mobilization from adipose tissue. There is no impairment of hepatic synthesis of protein after ethanol ingestion. Oxidation of ethanol by alcohol dehydrogenase leads to excess production of NADH. 

It is well established that the main products of ethanol electro-oxidation on Pt in acidic media are acetaldehyde and acetic acid, partial oxidation products that do not require C—C bond breaking, with their relative yields depending on the experimental conditions [Iwasita and Pastor, 1994]. Apart from the loss of efficiency associated with the partial oxidation, acetic acid is also unwanted, as it constitutes a catalyst poison. 

Infrared spectroscopy has also been employed to follow the formation of acetaldehyde and acetic acid on Pt during ethanol electro-oxidation. On the basal planes, acetaldehyde could be observed starting at about 0.4 V (vs. RHE), well before the onset of CO oxidation, while the onset of acetic acid formation closely follows CO2 formation [Chang et al., 1990 Xia et al., 1997]. This is readily explained by the fact that both CO oxidation and acetic acid formation require a common adsorbed co-reactant, OHads, whereas the formation of acetaldehyde from ethanol merely involves a relatively simple proton-electron transfer. 

Isolation of Oxidation Products. After oxygen absorption had ceased, or reached the desired value, the oxidates were poured into water. In many cases the reaction product could be removed by filtration in high yield. In this manner xanthone (m.p. 172-174°C.), was isolated from oxidations of xanthene or xanthen-9-ol thioxanthone (m.p. 208-210°C.), from thioxanthene acridine (m.p. 107-109°C.), from acridan anthracene (m.p. 216-217°C.), from 9,10-dihydroanthracene phenanthrene (m.p. 95-99°C.), from 9,10-dihydrophenanthrene pyrene (m.p. 151-152.5°C.) (recrystallized from benzene) from 1,2-dihydropyrene and 4-phenan-throic acid (m.p. 169-171 °C.) (recrystallized from ethanol) by chloroform extraction of the hydrolyzed and acidified oxidate of 4,5-methyl-enephenanthrene. 

Early examples of electron transfer processes are shown in equations (2), (12), and (13). Birch in 1944 followed up the findings of Wooster, and demonstrated that Na metal and ethanol in ammonia reduce benzene, anisole, and other aromatics to 1,4-cyclohexadienes. Birch speculated about the mechanism of this reaction, but did not explicitly describe a radical pathway involving 55 (equation 87) until later, as described in his autobiography. Electron transfer from arenes was found by Weiss in 1941, who obtained crystalline salts of Ci4H]o from oxidation of anthracene. ... 

CLA as An Antioxidant. The complete mechanism of anticarcinogenic activity of CLA is not known. Some of the CLA effect is believed due to its antioxidant properties. For example, use of a water/ethanol system that is incubated at 40"C under air for 14 days, showed CLA reduced the oxidation of linoleic acid by 86% (8), Under the same conditions a-tocopherol reduced oxidation by only 63% and butylated hydroxytoluene (BHT) reduced oxidation by 92%. Dose-response studies were conducted, and it was found that the optimal ratio for CLA to protect linoleic acid from oxidation is 1 1000 (CLAilinoleic acid). 

Iodide-promoted reactions in phosphine oxide solvents have been observed under some conditions to produce ethanol from H2/CO with good rates and high selectivities (193-195) (Table XVI, Expts. 1-3). Experimental evidence suggests that the ethanol is a secondary product, although its selectivity is high even after very short reaction times (193). An acid component is believed to be involved in alcohol homologation by this system, which will be described in more detail below. 

The buffers are uniformly made up of lithium citrate solutions of various pH and salt concentrations. The composition of the buffers is absolutely essential for a reproducible analysis and the supply companies are expected to meet the highest criteria in this respect. Due to impurities in the chemicals, the water, and the mixing devices, different lot numbers of buffers may have slightly different properties. A few tricks have been added over the years to improve the quality of the analysis, including the addition of methylcellosolve (methoxy ethanol) to the first buffer, and antioxidants to preserve methionine from oxidation to methionine sulfoxide. 

The values of AGox (Table 6-4) not only give an immediate indication of the relative amounts of energy available from oxidation of substrate with NAD+ but also are very convenient in evaluating AG for fermentation reactions. For example, consider the fermentation of glucose to ethanol (Eq. 6-60) ... 

When ethanol is oxidized by the action of alcohol dehydrogenase (Eq. 9-73), only the pro-R hydrogen atom is removed. If the reaction is reversed in such a way that deuterium is introduced into ethanol from the reduced coenzyme the optically active R-2-deuterio-ethanol is formed. The ability of an enzyme to... 

Some catabolic reactions depend upon ADP, but under most conditions its concentration is very low because it is nearly all phosphorylated to ATP. Reactions utilizing ADP may then become the rate-limiting pacemakers in reaction sequences. Depletion of a reactant sometimes has the effect of changing the whole pattern of metabolism. Thus, if oxygen is unavailable to a yeast, the reduced coenzyme NADH accumulates and reduces pyruvate to ethanol plus C02 (Fig. 10-3). The result is a shift from oxidative metabolism to fermentation. 

When wine spoils, ethanol is oxidized to acetic acid as 02 from the air reacts with the wine ... 

Sodium alkanetellurolates, prepared by cleavage of the acetylene moiety from alkyl phenylethynyl tellurium compounds with sodium borohydride in ethanol or with hydrazine/sodium hydroxide (diimide) in ethanol, were oxidized to dialkyl ditellurium derivatives by air4. 

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