Organic acids ineffectiveness

Oxime methanesulfonates are also suitable rearrangement substrates. Thus, the azetidinone oxime methanesulfonate (18) underwent smooth rearrangement upon exposure to basic alumina (equation 13) more conventional mineral and organic acid based reagents were ineffective in promoting this transformation. 

The effect of temperature is linked to the availability of water. The dry air of hot, arid environments is an ineffective weathering agent. Vegetation and hence soil organic matter are sparse, and this reduces the concentration of organic acids. Moreover, close contact between rock particles and acid is prevented by the lack of water. Short-lived rainfall events may move surface salts into the soil, but the... 

Bolton, D.J., Catarame, T., Byrne, C., Sheridan, J.J., McDowell, D.A., and Blair, I.S. 2002. The ineffectiveness of organic acids, freezing and pulsed electric fields to control Escherichia coli 0157 H7 in beef burgers. Letters in Applied Microbiology 34 139-143. 

Better results were obtained with catalysts of the type of quaternary phosphonium nickel halogenides or the corresponding ammonia compounds [408, 409]. Nickel bromide and nickel iodide are only soluble in butyl acrylate/butanol mixtures in amounts which are insufficient for the maintenance of the catalytic process. As mentioned in patents [408, 409], tertiary and quaternary complex compounds supply the required concentration of nickel and halogen ions for a continuous reaction. Many of the carbonylations, especially the stoichiometric reactions with Ni(CO)4 are carried out in the presence of water and acids. Jones [369] investigated the efficiency of the monobasic acids and showed hydrochloric acid and acetic acid to be of the same efficiency, whereas trichloro acetic acid is inefficient. He concludes that not the protons of the acids but the anions are of importance in the reaction mechanism. Apart from hydrochloric acid and acetic acid [345], sulfuric acid, aqueous phosphoric add, formic acid [367] and monochloroacetic acid are suited. A number of other organic acids [367] are ineffective. Acetic acid may be used in less than the equivalent amount because the unsaturated acid formed in the hydrocarbox-ylation [367] may replace acetic acid. 

Polymers that are crosslinked by peroxide or other means are among the easiest, with unsaturated groups such as vinyl or methacryl being adequate. There has been a lot of interest in unsaturated organic acids especially oleic and similar types, but, with the exception of acrylic and methacrylic acids, these have generally been found to be ineffective. While acrylic and methacrylic acids can achieve coupling, they are not easy to use. 

The observation of nitration at a rate independent of the concentration and nature of the aromatic excludes AcONOa as the reactive species. The fact that zeroth-order rates in these solutions are so much faster than in solutions of nitric acid in inert organic solvents, and the fact that HNO3 and H2NO3+ are ineffective in nitration even when they are present in fairly lai e concentrations, excludes the operation of either of these species in solutions of acetyl nitrate in acetic anhydride. 

Transition-metal-based Lewis acids such as molybdenum and tungsten nitro-syl complexes have been found to be active catalysts [49]. The ruthenium-based catalyst 50 (Figure 3.6) is very effective for cycloadditions with aldehyde- and ketone-bearing dienophiles but is ineffective for a,)S-unsaturated esters [50]. It can be handled without special precautions since it is stable in air, does not require dry solvents and does not cause polymerization of the substrates. Nitromethane was the most convenient organic solvent the reaction can also be carried out in water. 

The degradation of tetrachloromethane by Pseudomonas stutzeri strain KC involves hydrolysis to CO2 by a mechanism involving the natnrally prodnced pyridine-2,6-dithiocarboxylic acid (Lewis et al. 2001) details have already been discnssed in Chapter 7, Part 3. This organism was nsed in field evaluation at a site at which the indigenons flora was ineffective, and acetate was used as electron donor (Dybas et al. 2002). One novel featnre was inocnlation at a series of wells perpendicnlar to the established flow of the gronndwater plnme. Effective removal of tetrachloromethane was snstained over a period of 4 years, and transient levels of chloroform and H2S disappeared after redncing the concentration of acetate. 

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