Propionic acid, from oxidation

Succinyl-CoA derived from propionyl-CoA can enter the TCA cycle. Oxidation of succinate to oxaloacetate provides a substrate for glucose synthesis. Thus, although the acetate units produced in /3-oxidation cannot be utilized in glu-coneogenesis by animals, the occasional propionate produced from oxidation of odd-carbon fatty acids can be used for sugar synthesis. Alternatively, succinate introduced to the TCA cycle from odd-carbon fatty acid oxidation may be oxidized to COg. However, all of the 4-carbon intermediates in the TCA cycle are regenerated in the cycle and thus should be viewed as catalytic species. Net consumption of succinyl-CoA thus does not occur directly in the TCA cycle. Rather, the succinyl-CoA generated from /3-oxidation of odd-carbon fatty acids must be converted to pyruvate and then to acetyl-CoA (which is completely oxidized in the TCA cycle). To follow this latter route, succinyl-CoA entering the TCA cycle must be first converted to malate in the usual way, and then transported from the mitochondrial matrix to the cytosol, where it is oxida-... 

Although aldehydes are more easily ozidized than alcohols, reagents and conditions are similar in the conversion of both substances to acids. Sulfuric-chromic acid mixture has been used to prepare propionic acid from the alcohol (65%), heptanoic acid from the aldehyde (70%), and furoic acid from furfural (75%). ° Alkaline permanganate is employed in the preparation of methyldiphenylacetic acid from the aldehyde (45%) and ethyl-n-butylacetic acid from the aldehyde or alcohol (74%). ° Acid permanganate is used for the oxidation of heptaldehyde to heptanoic acid (78%) and 6-methyl-l-octanol to 6-methyloctanoic acid (66%). ... 

From Lactic Acid.—When lactic acid, a-hydroxy propionic acid, is oxidized pyro-racemic acid is obtained as was recently stated (p. 248). Also pyro-racemic acid may be reduced to lactic acid. 

Thus the homologation reaction can be used, for example, for the synthesis of acetaldehyde from methanol [48], propionic acid from acetic acid [47], or ethyl acetate from methyl acetate [50]. Styrene may be produced from toluene by oxidation to benzyl alcohol [51] and homologation to 2-phenylethanol, which in turn can be dehydrated to styrene. From the chemical point of view, the applications of homologation reactions are broad and useful. But, as mentioned before, low selec-... 

With respect to the oxidation of the side chain in chenodeoxycholic acid formation, it may be inferred from the early studies with mitochondrial preparations that it involves an co-oxidation followed by a / -oxidation (cf. Section IIB). More direct evidence has been presented by Dean and White-house (87,91), who showed that mitochondrial preparations from rat liver catalyze the oxidation of 5-cholestene-3/ ,26-diol into 3/ -hydroxy-5-choles-tenoic acid and the formation of propionic acid from 3/5-hydroxy-5-choles-tenoic acid. Mitropoulos and Myant (97) have shown that mitochondrial preparations from rat liver catalyze the conversion of cholesterol into 5-cholestene-3/ ,26-diol, 3/ -hydroxy-5-cholestenoic acid, 3/5-hydroxy-5-chole-noic acid, lithocholic acid, and chenodeoxycholic acid (Fig. 5). Additional evidence for a pathway to chenodeoxycholic acid involving the successive, intermediary formation of above-mentioned compounds is provided by the finding that 3/ -hydroxy-5-cholenoic acid is converted into lithocholic acid and chenodeoxycholic acid by mitochondrial preparations (98). 

SuLD, H. M., E. Staple, and S. Gurin Mechanism of formation of bile acids from cholesterol Oxidation of 3j5-cholestane-3a, 7a, 12a-triol and formation of propionic acid from the side chain by rat liver mitochondria. J. biol. Chem. 237, 338 (1962). 

More recently Brown and Kies (S65) reported the formation from histidine and the excretion in the urine of hydantoin- propionic acid, and also its formation by liver extracts of guinea pig and the rat. The substrate for the oxidation was shown very probably to be imidazolone-propionic acid. No oxidation or formation of hydantoinpropionic acid could be demonstrated if the urocanase activity was first destroyed. The L-hydantoin-5-propionic acid was isolated by chromati raphy, and crystallized. Its identity was unequivocally established. 

Butane-Naphtha Catalytic Liquid-Phase Oxidation. Direct Hquid-phase oxidation ofbutane and/or naphtha [8030-30-6] was once the most favored worldwide route to acetic acid because of the low cost of these hydrocarbons. Butane [106-97-8] in the presence of metallic ions, eg, cobalt, chromium, or manganese, undergoes simple air oxidation in acetic acid solvent (48). The peroxidic intermediates are decomposed by high temperature, by mechanical agitation, and by action of the metallic catalysts, to form acetic acid and a comparatively small suite of other compounds (49). Ethyl acetate and butanone are produced, and the process can be altered to provide larger quantities of these valuable materials. Ethanol is thought to be an important intermediate (50) acetone forms through a minor pathway from isobutane present in the hydrocarbon feed. Formic acid, propionic acid, and minor quantities of butyric acid are also formed. 

Dehydrogenation of Propionates. Oxidative dehydrogenation of propionates to acrylates employing vapor-phase reactions at high temperatures (400—700°C) and short contact times is possible. Although selective catalysts for the oxidative dehydrogenation of isobutyric acid to methacrylic acid have been developed in recent years (see Methacrylic ACID AND DERIVATIVES) and a route to methacrylic acid from propylene to isobutyric acid is under pilot-plant development in Europe, this route to acrylates is not presentiy of commercial interest because of the combination of low selectivity, high raw material costs, and purification difficulties. 

Anhydrous Acetic Acid. In the manufacture of acetic acid by direct oxidation of a petroleum-based feedstock, solvent extraction has been used to separate acetic acid [64-19-7] from the aqueous reaction Hquor containing significant quantities of formic and propionic acids. Isoamyl acetate [123-92-2] is used as solvent to extract nearly all the acetic acid, and some water, from the aqueous feed (236). The extract is then dehydrated by azeotropic distillation using isoamyl acetate as water entrainer (see DISTILLATION, AZEOTROPIC AND EXTRACTIVE). It is claimed that the extraction step in this process affords substantial savings in plant capital investment and operating cost (see Acetic acid and derivatives). A detailed description of various extraction processes is available (237). 

Only with propanal are very high conversions (99%) and selectivity (> 98 0) to MMA and MAA possible at this time. Although nearly 95% selective, the highest reported conversions with propionic acid or methyl propionate are only 30—40%. This results in large recycle streams and added production costs. The propanal route suffers from the added expense of the additional step required to oxidize methacrolein to methacrylic acid. 

Chloro-2,2,3-trifluoropropionic acid has been prepared by permanganate oxidation of 3-chloro-2,2,3-trifluoropropanol which is one of the telomerization products of chlorotrifluoroethylene with methanol. The present procedure is a modification of one reported earlier and is undoubtedly the method of choice for making propionic acids containing 2 fluorine atoms, i.e., 2,2,3,3-tetrafluoropropionic acid, 3,3-dichloro-2,2-difluoropropionic acid, and 3-bromo-2,2,3-trifluoropropionic acid. When preparing 2,2,3,3-tetrafluoropropionic acid from tetrafluoroethylene, it is desirable to use an additional 50 ml. of acetonitrile and externally applied heat to initiate the reaction. 

Coumarin (7.88) is a well-known 6-lactone (six-membered ring) of natural origin found in various preparations such as some tobaccos, alcoholic beverages, and cosmetics. Besides reactions of oxidation, reduction, and conjugation, coumarin is also subject to lactone hydration in vivo and in the presence of microsomes [170-174], The resulting metabolites include ortho-coumaric acid (7.89) formed directly from coumarin, 3-(2-hydroxyphenyl)-propionic acid (7.91) formed following reduction of coumarin to dihydrocou-... 

These short-chain fatty acids are acetic, butyric, lactic and propionic acids, also known as volatile fatty acids, VFA. They are produced from fermentation of carbohydrate by microorganisms in the colon and oxidised by colonocytes or hepatocytes (see above and Chapter 4). Butyric acid is activated to produce butyryl-CoA, which is then degraded to acetyl-CoA by P-oxidation acetic acid is converted to acetyl-CoA for complete oxidation. Propionic acid is activated to form propionyl-CoA, which is then converted to succinate (Chapter 8). The fate of the latter is either oxidation or, conversion to glucose, via glu-coneogenesis in the liver. 

Beccalli et al. reported a new synthesis of staurosporinone (293) from 3-cyano-3-(lH-indol-3-yl)-2-oxo propionic acid ethyl ester (1464) (790). The reaction of 1464 with ethyl chlorocarbonate and triethylamine afforded the compound 1465, which, on treatment with dimethylamine, led to the corresponding hydroxy derivative 1466. The triflate 1467 was prepared from 1466 by reaction with trifluoromethanesulfonic anhydride (Tf20) in the presence of ethyldiisopropylamine. The palladium(O)-catalyzed cross-coupling of the triflate 1467 with the 3-(tributylstannyl)indole 1468 afforded the vinylindole 1469 in 89% yield. Deprotection of both nitrogen atoms with sodium ethoxide in ethanol to 1470, followed by photocyclization in the presence of iodine as the oxidizing agent provided the indolocarbazole 1471. Finally, reductive cyclization of 1471 with sodium borohydride-cobaltous chloride led to staurosporinone (293) in 40% yield (790) (Scheme 5.248). 

Ozonolysis of alkynes followed by hydrolysis gives similar products to those obtained from permanganate oxidation. This reaction does not require oxidative or reductive work-up. Unsubstituted carbon atoms are oxidized to CO2, and mono-substituted carbon atoms to carboxylic acids. For example, ozonolysis of 1-butyene followed by hydrolysis gives propionic acid and carbon dioxide. 

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