Water-soluble aromatic ketones

PMVEMA, supphed as a white, fluffy powder, is soluble in ketones, esters, pyridine, lactams, and aldehydes, and insoluble in aUphatic, aromatic, or halogenated hydrocarbons, as well as in ethyl ether and nitroparaffins. When the copolymer dissolves in water or alcohols, the anhydride group is cleaved, forming the polymers in free acid form or the half-esters of the corresponding alcohol, respectively. Table 7 illustrates the commercially available alternating copolymers and derivatives. 

Alkyne-nitrile cyclotrimerization is a powerful synthetic methodology for the synthesis of complex heterocyclic aromatic molecules.118 Recently, Fatland et al. developed an aqueous alkyne-nitrile cyclotrimerization of one nitrile with two alkynes for the synthesis of highly functionalized pyridines by a water-soluble cobalt catalyst (Eq. 4.62). The reaction was chemospecific and several different functional groups such as unprotected alcohols, ketones, and amines were compatible with the reaction.119 In addition, photocatalyzed [2+2+2] alkyne or alkyne-nitrile cyclotrimerization in water120 and cyclotrimerization in supercritical H2O110121 have been reported in recent years. 

Qualitative spot tests for aldehydes, in the presence of ketones, are generally only reliable for water-soluble compounds. This problem can be overcome by the use of 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole (Purpald , Aldrich Chemical Company) in the presence of Aliquat (Scheme 5.27). Under aerial oxidation, the initially formed colourless cyclic adduct changes colour through red to purple. The colourless cyclic aminal can also be formed by ketones, but only the adducts derived from the aldehydes are oxidized to the purple bicyclic aromatic system [28]. Weakly electrophilic aldehydes, e.g., 4-methoxybenzaldehyde, reacts slowly, but will give the positive coloration upon gentle heating to ca. 70°C for one or two minutes. 

Analogous water-soluble Cp Rh and Cp lr complexes were prepared by Williams et al., and used in the asymmetric transfer hydrogenation of aromatic ketones under aqueous conditions [43]. These catalyst complexes contain water-soluble chiral diamine ligands (Scheme 5.11), and were prepared in situ by reacting [Cp MCl2]2 (M = Rh, Ir) with ligands 15a or 15b in the presence of a base, and used immediately. The results of the asymmetric transfer hydrogenation of... 

Aqueous biphasic catalysis is also used in homogeneous hydrogenations.117-119 In new examples Ru clusters with the widely used TPPTN [tris(3-sulfonatophenyl) phosphine] ligand120 and Rh complexes with novel carboxylated phosphines121 were applied in alkene hydrogenation, whereas Ru catalysts were used in the hydro-genation of aromatics. Aerobic oxidation of terminal alkenes to methyl ketones was carried out in a biphasic liquid-liquid system by stable, recyclable, water-soluble Pd(II) complexes with sulfonated bidentate diamine ligands.124... 

In subsequent steps, DAS is treated in acidic aqueous solution at 0-5 °C with cyanuric chloride dissolved in ethyl methyl ketone. The remaining chlorine atoms are then replaced by aliphatic, cycloaliphatic, or aromatic amines at 15-35 °C and then at ca. 60 °C. The addition of electrolytes (e.g., sodium carbonate, sodium hydroxide) or water-soluble aprotic solvents at 90 to 100 °C or above leads to the desired 3 crystal modification, which is nearly colorless. 

As molecular weight increases, the hydrophobic character of the attached alkyl chains begins to outweigh the water solubility of the carbonyl group and the result is that large molecular weight aldehydes and ketones are insoluble in water. Aromatic ketones and aldehydes are insoluble in water because of the hydrophobic aromatic ring. 

Reactions with these compounds suffer from very low substrate concentrations due to the low solubility of hydrophobic ketone substrates in aqueous media, which leads to unsatisfactory volumetric productivities. To achieve higher substrate concentrations, a biphasic reaction medium was introduced. The system water/ n-heptane (4 1) proved to be the most suitable system with regard to stability of the examined enzymes. The large-scale available (S)-specific ADH from R. erythropolis as well as FDH from C. boidinii are stable for long periods of time in this aqueous-organic solvent system. Preparative conversions with a variety of aromatic ketone substrates were carried out with this reaction medium. For example, p-chloroacetophenone was converted into the corresponding (S )-alcohol with >99% ee and 69% conversion. The obvious increase in volumetric productivity is due to the higher substrate concentrations. The reduction of p-chloroacetophenone... 

A9.6.4.7 The Nordic Council of Ministers issued a report (Pederson et al, 1995) entitled Environmental Hazard Classification, that includes information on data collection and interpretation, as well as a section (5.2.8) entitled QSAR estimates of water solubility and acute aquatic toxicity . This section also discusses the estimation of physicochemical properties, including log Kow For the sake of classification purposes, estimation methods are recommended for prediction of minimum acute aquatic toxicity, for ...neutral, organic, non-reactive and non-ionizable compounds such as alcohols, ketones, ethers, alkyl, and aryl halides, and can also be used for aromatic hydrocarbons, halogenated aromatic and aliphatic hydrocarbons as well as sulphides and disulphides, as cited in an earlier OECD Guidance Document (OECD, 1995). The Nordic document also includes diskettes for a computerized application of some of these methods. 

Properties Green plastic solid. Soluble in water, aliphatic hydrocarbons, ketones and aromatic hydrocarbons partially soluble in alcohols and glycols soluble in Softening p 64C. 

Properties Yellow solid or liquid. D 1.2458 (30/ 4C), mp 29-30C, refr index 1.4893 (42C). Insoluble in water soluble in alcohols, ketones, aromatic and chlorinated hydrocarbons. Also available as methyl ester. 

Properties White crystals aromatic odor. Mp 41.0C (min). Insoluble in water soluble in alcohol, ketones, and esters. Combustible. 

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