Acrylic acid pathway

Another highly potential production species is the gram-positive bacteria Clostridium propionicum. This microorganism is able to utilise lactate, glycerol and alanine as substrate. Propionate, acetate, formate, n-propanol and succinate are produced. The optimal pH value is 6.8 and the best temperature is 30 °C. C. propionicum uses the acrylic acid pathway to produce the desired product... 

The surface transformations of propylene, allyl alcohol and acrylic acid in the presence or absence of NHs over V-antimonate catalysts were studied by IR spectroscopy. The results show the existence of various possible pathways of surface transformation in the mechanism of propane ammoxidation, depending on the reaction condition and the surface coverage with chemisorbed NH3. A surface reaction network is proposed and used to explain the catalytic behavior observed in flow reactor conditions. 

Co-adsorption experiments show a complex role of the nature and concentration of chemisorbed ammonia species. Ammonia is not only one of the reactants for the synthesis of acrylonitrile, but also reaction with Br()>nsted sites inhibits their reactivity. In particular, IR experiments show that two pathways of reaction are possible from chemisorbed propylene (i) to acetone via isopropoxylate intermediate or (ii) to acrolein via allyl alcoholate intermediate. The first reaction occurs preferentially at lower temperatures and in the presence of hydroxyl groups. When their reactivity is blocked by the faster reaction with ammonia, the second pathway of reaction becomes preferential. The first pathway of reaction is responsible for a degradative pathway, because acetone further transform to an acetate species with carbon chain breakage. Ammonia as NH4 reacts faster with acrylate species (formed by transformation of the acrolein intermediate) to give an acrylamide intermediate. At higher temperatures the amide may be transformed to acrylonitrile, but when Brreform ammonia and free, weakly bonded, acrylic acid. The latter easily decarboxylate forming carbon oxides. 

However, the two syntheses of Tamiflu, involving two potentially hazardous azide-containing intermediates, need further improvements. A recently published short and enantioselective pathway starting from acrylic acid and 1,3-butadiene looks promising [47]. 

The oxidation of aciy lic acid can be rationalized in terms of the endogenous catabolism of propionic acid, in which acrylyl coenzyme A is an intermediate. This pathway is analogous with fatty acid 3-oxidation, common to all species and, unlike the corresponding pathway in plants, does not involve vitamin 8,2. 3-Hydroxypropionic acid has been found as an intennediate in the metabolism of acrylic acid in vitro in rat liver and mitochondria (Finch Frederick, 1992). The CO2 excreted derives from the carboxyl carbon, while carbon atoms 2 and 3 are converted to acetyl coenzyme A, which participates in a variety of reactions. The oxidation of acrylic acid is catalysed by enzymes in a variety of tissues (Black Finch, 1995). In mice, the greatest activity was found in kidney, which was five times more active than liver and 50 times more active than skin (Black et al., 1993). 

Y. Y. Yeung, S. Hong, and E. J. Corey, A short enantioselective pathway for the synthesis of the anti-influenza neuramidase inhibitor oseltamivir from 1,3-butadiene and acrylic acid, J. Am. Chem. Soc., 128 (2006) 6310-6311. 

The Michael addition mechanism, whereby sulfur nucleophiles react with organic molecules containing activated unsaturated bonds, is probably a major pathway for organosulfur formation in marine sediments. In reducing sediments, where environmental factors can result in incomplete oxidation of sulfide (e.g. intertidal sediments), bisulfide (HS ) as well as polysulfide ions (S 2 ) are probably the major sulnir nucleophiles. Kinetic studies of reactions of these nucleophiles with simple molecules containing activated unsaturated bonds (acrylic acid, acrylonitrile) indicate that polysulfide ions are more reactive than bisulfide. These results are in agreement with some previous studies (30) as well as frontier molecular orbital considerations. Studies on pH variation indicate that the speciation of reactants influences reaction rates. In seawater medium, which resembles pore water constitution, acrylic acid reacts with HS at a lower rate relative to acrylonitrile because of the reduced electrophilicity of the acrylate ion at seawater pH. 

Phenoxypropanoic acid, 3-(phenylthio)propanoic acid, 4-phenylbutanoic acid and the corresponding ethyl and methyl esters have been pyrolysed between 520 and 682 K.10 Analysis of the pyrolysates showed the elimination products to be acrylic acid and the corresponding arene. The thermal gas-phase elimination kinetics and product analysis have been found compatible with a thermal retro-Michael reaction pathway involving a four-membered cyclic transition state. 

Adsorption of block copolymers onto a surface is another pathway for surface functionalization. Block copolymers in solution of selective solvent afford the possibility to both self-assemble and adsorb onto a surface. The adsorption behavior is governed mostly by the interaction between the polymers and the solvent, but also by the size and the conformation of the polymer chains and by the interfacial contact energy of the polymer chains with the substrate [115-119], Indeed, in a selective solvent, one of the blocks is in a good solvent it swells and does not adsorb to the surface while the other block, which is in a poor solvent, will adsorb strongly to the surface to minimize its contact with the solvent. There have been a considerable number of studies dedicated to the adsorption of block copolymers to flat or curved surfaces, including adsorption of poly(/cr/-butylstyrcnc)-ft/od -sodium poly(styrenesulfonate) onto silica surfaces [120], polystyrene-Woc -poly(acrylic acid) onto weak polyelectrolyte multilayer surfaces [121], polyethylene-Wocfc-poly(ethylene oxide) on alkanethiol-patterned gold surfaces [122], or poly(ethylene oxide)-Woc -poly(lactide) onto colloidal polystyrene particles [123],... 

Draminski et al. (1983) administered 10 mg/kg of acrolein as a single oral dose to rats and collected the urine during 3 days. Since the metabolite S - carboxyethylmercapturic acid was found in the urine, but S - hydroxypropylmercapturic acid (which should have been formed if acrolein had reacted with glutathione) was not, an alternative pathway was proposed. In this metabolic scheme, acrolein is first metabolized to acrylic acid with subsequent formation of the methyl ester, which is then conjugated with glutathione to form S-carboxyethylmercapturic acid methyl ester. The metabolic pathway postulated by Draminski et al. (1983) is shown in Figure 2-4. 

V-Mo-P and V-Mo-Cs catalysts (251). The V-Mo-P catalysts are not selective therefore, at least two reaction pathways are important over this catalyst, and sufficient data were not available to characterize both pathways. The V-Mo-Cs catalysts showed low activity, and the adsorption of acrylic acid was irreversible, producing large errors in the determination of the heat effects of the reaction. 

In 2006, two groups independently reported the novel asymmetric synthesis of tamiflu (106). Corey et al. reported a short enantioselective pathway for the synthesis of 106 from 1,3-butadi-ene and acrylic acid shown in O Scheme 22 [ 111 ]. The key steps of the synthesis are (1) Diels-Alder reaction of 1,3-butadiene (146) and trifluoroethyl acrylate (147) in the presence of chiral ligand 148 developed in the laboratory [112], (2) the introduction of two amino groups in tamiflu (106) without using potentially hazardous and explosive azide reagents, and (3) a novel S nBr4 - catalyzed bromoacetamidation. 

Inhalation, skin and eye contact, and ingestion are the most common exposure pathways. Acrylic acid is available as a colorless liquid. 

In the environment. More generally, the results imply that a major chemical pathway for the Incorporation of sulfur into organic geopolymers is by reaction of HS with reactive sites, e.g. oleflnlc double bonds, displaceable halogens (39). within sedimentary organic matter. The Michael addition reaction of HS to acrylic acid may be used as a model case of such interactions. 

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