Ketones industrial source

While discussing ethers we should mention that the presence of unreacted anisoles or methyl anisoles is highly undesirable in the manufacture of phenol-formaldehyde resoles. These materials tend to be unreactive relative to phenol under normal resole conditions. They are also volatile and have odors detectable at very low concentrations. They have been the source of worker complaints and costly claims in the wood products industry. Benzophenones and methyl phenyl ketones are also common phenol contaminants that are problematic in this regard. 

Common alcohol oxidation methods employ stoichiometric amounts of toxic and reactive oxidants like Cr03, hypervalent iodine reagents (Dess-Martin) and peracids that pose severe safety and environmental hazards in large-scale industrial reactions. Therefore, a variety of catalytic methods for the oxidation of alcohols to aldehydes, ketones or carboxylic acids have been developed employing hydrogen peroxide or alkyl hydroperoxides as stoichiometric oxygen sources in the presence of catalytic amounts of a metal catalyst. The commonly used catalysts for alcohol oxidation are different MoAV(VI), Mn(II), Cr(VI), Re(Vn), Fe(II) and Ru complexes . A selection of published known alcohol oxidations with different catalysts will be presented here. 

All industrial vitamin A syntheses use p-ionone as the starting compound (36, see page 14) 3S). This monocyclic C13 ketone can be obtained either completely synthetically from acetone and acetylene by consequent use of the C2 and C3 addition reaction, or via citral (59, see page 14) obtainable from natural sources (lemongrass oil). 

Reactions of or Hj sources (e.g., Zn-HCl) with alkenes, alkynes, arenes, ketones, nitriles, carboxylic acids and esters are used industrially for C—H bond formation . Heterogeneous reaction catalysts (e.g., Ni, Pt, Pd, Fe, Ni-Cu) are used, e.g. ... 

Shortly after, the same group published a study where readily available carboxylic acids, diacids, and N-protected amino acids were screened as proton sources [6]. The same substrates were used in the presence of citric acid instead of HF. This catalytic system displayed somewhat lower selectivity. For example, by using similar experimental conditions in the presence of citric acid at —10 °C, the enantioseiective protonation of silyl enol ether 5c afforded the corresponding ketone 7c in excellent yield but lower enantioselectivity (up to 75% ee, Scheme 7.4, to be compared with entry 3, Table 7.1). However, upon further optimization, this process seems appealing in terms of simplicity, practicability, environmental concerns, and cost therefore, adjustable for industrial use. 

Outdoor sources Traffic, industry (aliphatic and aromatic hydrocarbons aldehydes ketones esters). 

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