Propionic acid, from propane

It IS hard to find a class of compounds in which the common names of its members have influenced organic nomenclature more than carboxylic acids Not only are the common names of carboxylic acids themselves abundant and widely used but the names of many other compounds are derived from them Benzene took its name from benzoic acid and propane from propionic acid not the other way around The name butane comes from butyric acid present m rancid butter The common names of most aldehydes are derived from the common names of carboxylic acids—valeraldehyde from valeric acid for exam pie Many carboxylic acids are better known by common names than by their systematic ones and the framers of the lUPAC rules have taken a liberal view toward accepting these common names as permissible alternatives to the systematic ones Table 19 1 lists both common and systematic names for a number of important carboxylic acids... 

MMA and MAA can be produced from ethylene [74-85-1/ as a feedstock via propanol, propionic acid, or methyl propionate as intermediates. Propanal may be prepared by hydroformylation of ethylene over cobalt or rhodium catalysts. The propanal then reacts in the Hquid phase with formaldehyde in the... 

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. 

The principal competing reactions to ruthenium-catalyzed acetic acid homologation appear to be water-gas shift to C02, hydrocarbon formation (primarily ethane and propane in this case) plus smaller amounts of esterification and the formation of ethyl acetate (see Experimental Section). Unreacted methyl iodide is rarely detected in these crude liquid products. The propionic acid plus higher acid product fractions may be isolated from the used ruthenium catalyst and unreacted acetic acid by distillation in vacuo. 

Ethylene-Based (C-2> Routes. MMA and MAA can be produced from ethylene as a feedstock via propanol, propionic acid, or melhyl propionate as intermediates. Propanal may be prepared by hydrofonnylalion of ethylene over cobalt or rhodium catalysts. The propanal then reads in the liquid phase with formaldehyde in the presence of a secondary amine and. optionally, a carboxylic acid. The reaction presumably proceeds via a Mannich base intermediate which is cracked to yield methacrolcin. Alternatively, a gas-phase, crossed akin I reaelion with formaldehyde cataly zed by molecular sieves [Pg.988]

Clausen et al. (2005) found many similarities between odorants emitted from linseed oil as well as from a floor oil made of this linseed oil, concluding that the odorants of the linseed oil are also responsible for the odor of the floor oil. Of the 139 listed perceived odorants only 45 were identified by GC—MS library search and retention characteristics. Important odorants with a high detection frequency were acetaldehyde, propanal, butanal, pentanal, 2-pentenal, hexanal, 2-hexenal, heptanal, 2-heptenal, 2,4-heptadienal, octanal, 2-octenal, nonanal, 2-nonenal, 2-decenal, benzaldehyde, l-penten-3-one, l-penten-3-ol, pentyl oxiran, acetic acid, propionic acid, butanoic acid, pentanoic acid, hexanoic acid, octanoic acid. 

Direct incorporation of molecular oxygen as 02 (Imada et ai, 1967) shows that the initial reaction is catalysed by an oxygenase and necessarily depends on oxygen. The most favorable position for attachment is the Cl position. The only stable metabolic product which could be isolated is the homologous normal alcohol Besides this so-called C] oxidation, there exists as another possibility, C2 oxidation. It could be shown from the example of Pseudomonas methanica that propane is oxidized into a mixture of propionic acid and acetone. In this case, R-alkanes are converted by intact cells into methyl ketone and also into the corresponding fatty acid. Other assumptions postulate that the C2 oxidation occurs on the basis of an equilibrium between the radicals of the Cl and C2 positions. 

Propane-l,2- C, specific activity of about 110 mCi mmol" has been synthesized from doubly labelled acetylene in reaction series shown in equation 12. This synthesis included preparation of doubly labelled acetylene from barium carbonate-according to Cox and Warne, nearly quantitative hydrogenation of acetylene to ethylene, addition of hydroiodic acid to the latter to form iodoethane, preparation of ethylmagnesium iodide followed by carbonation to yield propionic acid and reduction o n-propanol with 70-75% yield. The latter yielded a tosylate which was finally reduced to doubly labelled propane 2 with sodium borohydride, and purified by gas chromatography on alumina or silica. Its specific activity was close to the maximal possible specific activity of acetylene (i.e. 124.9 mCi mmol " ). 

The minor is-o-butanal isomer R-CH-(CHO)-CH3 also forms. The aldehydes are intermediates of choice for the synthesis of alcohols (by hydrogenation), leading to detergents and plastifiers, and for the synthesis of carboxylic acids (by oxidation using Oi). For instance, propionic acid is synthesized from ethylene via propanal. 

Methionine and cysteine are metabolized into volatile sulfur compounds. The O. oeni species is particularly active in converting cysteine into hydrogen sulfide and 2-sulfanyl ethanol, and methionine into dimethyl disulfide, 3-(metha-sulfanyl) propanol, 3-(methasulfanyl) propan-l-ol and 3-(methasulfanyl) propionic acid. The most interesting of these compounds from a sensory point of view is 3-(methasnlfanyl) propionic acid, with its earthy, red-berry fruit nuances (Pripis-Nicolau, 2002). 

Chemical processes dominate the production of short-chain organic acids. The primary route of synthesis employs the "Oxo process (Billig and Bryant 1991). Propionic acid is made by oxo synthesis of propionaldehyde from ethylene, CO, and H2 with a rhodium catalyst. liquid-phase oxidation of the aldehyde yields propionic add. Butyric acid is made by air oxidation of butyraldehyde, which is synthesized by the 0x0 process fi-om propylene, CO, and H2. The triphenylphosphine-modified rhodium 0x0 process, termed the LP Oxo process, is the industry standard for the hydroformylation of ethylene and propylene (Billig and Bryant 1991). Also pure propionic acid can be obtained from propionitrile or by oxidation of propane gas. 

Experiments under static conditions gave liquid products containing various oxygenates, such as methanol, ethanol, acetaldehyde, acetic acid, -propanol, isopropanol, propionalde-hyde, acetone, acrolein, propionic acid, and acrylic acid. The gas phase contained methane, ethane, and ethylene. The conversion of propane ranged from 15% to 61% at a total selectivity of up to 15% to liquid oxygenates and 10% to Ci—C2 hydrocarbons. 

Under flow conditions, the propane conversion was varied from 30 to 100% by changing the residence time in the reactor and the oxygen concentration. In all cases, methanol was the main liquid product (as in the gas-phase oxidation), which was formed with a selectivity of 12%. In addition, acetone and acetic acid were formed, and to a lesser extent ethanol, acetaldehyde, propionaldehyde and propionic acid, and carbon oxides. The total selectivity to oxygenates reached 15%, whereas the composition of the product was similar that observed in the static experiments. 

Several studies of O2 uptake by pre-adsorbed 77-allyl species confirm that a surface complex is initially formed. With a surface 7r-allyl concentration of 50% saturation (to minimize reactions between w-allyls and oxidation intermediates), i.r. spectra of the intermediate were compared with those obtained from separate adsorption of molecules which were likely candidates. Kugler and Kokes concluded from this approach that the intermediate was indeed acrolein, on account of a 1 1 correspondence of the spectra. Other candidates studied were allene, propanal, propan-l-ol, propan-2-ol, acetone, propionic and acetic acids, and acetaldehyde. Only the spectra for acrolein resembled that produced from propene plus O2. 

These compounds are prepared starting from chloroace-tic acid or its ethyl ester. For chains longer than acetic, cya-noethylation and hydrolysis of the nitrile obtained leads to the propionic chain, alkylation with ethyl 4-bromobutyrate and saponification leads to the butyric chain. The propane-sulfonic chains are particularly accessible by means of ring opening of propane-sultone. 

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