Ketones processes

The properties of the solids most commonly encountered are tabulated. An important problem arises for petroleum fractions because data for the freezing point and enthalpy of fusion are very scarce. The MEK (methyl ethyl ketone) process utilizes the solvent s property that increases the partial fugacity of the paraffins in the liquid phase and thus favors their crystallization. The calculations for crystallization are sensitive and it is usually necessary to revert to experimental measurement. 

S. A.cetone, Methj/ Ethj/ Ketone, and Methyl Isohutyl Ketone, Process Economics Program, Report No. 77, SRI, Menlo Park, Calif., May 1972. 

The enolate involved in the conversion of 3-dehydroquinate into 3-dehydroshiki-mate can be sterically and electronically mimicked by a vinyl fluoride. However, the ketonization process is impossible. This vinyl fluoride is a competitive inhibitor of dehydroquinase II that is 20 times more powerful than the nonfluorinated analogue (Figure 7.7). Moreover, it is very selective toward dehydroquinase I, whUe it acts according to a different mechanism. ... 

New catalysts are exemplified by the chlorine-free Pd /Mo-V-P heteropolycompound systems developed to replace Wacker PdCl2/CuCl2 catalysts in olefin-to-ketone processes (S). 

This process is sometimes referred to as the acetone-benzene (A-B) process or MEK (methyl ethyl ketone) process. 

J.-M. Bregeault, C. Lepetit, F. Ziani-Derdar, O. Mohammed i, L. Salles, A. Deloffre, Epoxidation of tertiary allylic alcohols and subsequent isomerization of tertiary epoxy-alcohols A comparison of some catalytic systems for demanding ketonization processes, in R. K. Grasselli, S. T. Oyama, A. M. Gaffney, J. E. Lyons (Eds.), 3rd World Congress on Oxidation Catalysis, Elsevier, Amsterdam, Stud. Surf. Sci. Catal. 110 (1997) 545. 

Epoxidation of tertiary allylic alcohols and subsequent isomerization of tertiary epoxy-alcohols a comparison of some catalytic systems for demanding ketonization processes... 

If further increases in dehydrogenation activity are desirable in the ketonization process, a d -d transition metal can be supported on the active oxide layer. " There can be lost yield to saturated hydrocarbons. Most of the commonly used transition metals exhibit limited miscibility with REOs. An exception is Cu. At ambient conditions, the Cu is mostly dispersed as Cu some Cu" can be maintained under reducing conditions even at 723 When supported on AI2O3, CeOx suppresses formation of inactive CUAI2O4 up to very high temperature. 

Fig. 30. Manufacture of photodegradable PS via in situ vinyl ketone process.

There are two main synthesis routes in commerce to produce MIBK. One starts with acetone and involves intermediates of diacetone alcohol and mesityl oxide. The second synthesis route uses 2-propanol, involving a mixed ketone process with coproducts including diisobutyl ketone (DIBK) and acetone. 

The sample to be analyzed can be dissolved in an organic solvent, xylene or methylisobutyl ketone. Generally, for reasons of reproducibility and because of matrix effects (the surroundings affect the droplet size and therefore the effectiveness of the nebulization process), it is preferable to mineralize the sample in H2SO4, evaporate it and conduct the test in an aqueous environment. 

Jent F, Paul H and Fischer H 1988 Two-photon processes in ketone photochemistry observed by time-resolved ESR spectroscopy Chem. Phys. Lett. 146 315-19... 

Phenylhydrazine on exposure to light slowly darkens and eventually becomes deep red in colour salts of the base share this property but to a lesser degree, the sulphate and acetate (of the common salts) being most stable to light. Phenylhydrazine is largely used in organic chemistry to characterise aldehydes and ketones as their phenyl-hydrazones (pp. 342, 345), and carbohydrates as their osazones (pp. 136-140). It is readily reduced thus in the process of osazone formation some of the phenylhydrazine is reduced to aniline and ammonia. On the... 

Dinitrophenylhydra2ones usually separate in well-formed crystals. These can be filtered at the pump, washed with a diluted sample of the acid in the reagent used, then with water, and then (when the solubility allows) with a small quantity of ethanol the dried specimen is then usually pure. It should, however, be recrystallised from a suitable solvent, a process which can usually be carried out with the dinitrophenylhydrazones of the simpler aldehydes and ketones. Many other hydrazones have a very low solubility in most solvents, and a recrystallisation which involves prolonged boiling with a large volume of solvent may be accompanied by partial decomposition, and with the ultimate deposition of a sample less pure than the above washed, dried and unrecrystal-lised sample. 

This preparation was discovered independently by Geuther (1863) and by Frankland and Duppa (1865). The reaction was subsequently investigated in detail and so w idely extended by Claisen that it has become solely a specific example of the more general process known as the Claisen Condensation. Claisen showed that an ester under the influence of sodium ethoxide would not only condense with itself (as in the preparation of ethyl acetoacetate), but also with (i) another ester, (ii) a ketone, if of formula RCHgCOR, (iii) a nitrile, if of formula RCH CN, in each case with the elimination of alcohol. Examples of these modifications are ... 

The industrial process for preparing the reagent usually permits a little hydrolysis to occur, and the product may contain a little free calcium hydroxide or basic chloride. It cannot therefore be employed for drying acids or acidic liquids. Calcium chloride combines with alcohols, phenols, amines, amino-acids, amides, ketones, and some aldehydes and esters, and thus cannot be used with these classes of compounds. 

Unsaturated hydrocarbons are present in nearly all products of the Clemmensen reduction of aromatic ketones and must be removed, if the hydrocarbon is requiral pure, by the above process. Secondary alcohols, often produced m small amount are not appreciably steam-volatile. 

Ethyl a-naphthylacetate is prepared as follows. To a solution of 10 g. of the diazo ketone in 150 ml. of ethanol at 55-60°, add a small amount of aslurry of silver oxide, prepared from 10 ml. of 10 per cent, aqueous silver nitrate and stirred with 25 ml. of ethanol. As soon as the evolution of nitrogen subsides, introduce more of the silver oxide and continue the process until all the slurry has been added. Reflux the mixture for 15 minutes, add 2-3 g. of decolourising carbon, filter and evaporate the alcohol on a water bath. Distil the residue and collect the ethyl a-naph-thylacetate at 176-178°/ 1 mm. the yield is 9 g. 

In a second attempt to extend the scope of Lewis-acid catalysis of Diels-Alder reactions in water, we have used the Mannich reaction to convert a ketone-activated monodentate dienophile into a potentially chelating p-amino ketone. The Mannich reaction seemed ideally suited for the purpose of introducing a second coordination site on a temporary basis. This reaction adds a strongly Lewis-basic amino functionality on a position p to the ketone. Moreover, the Mannich reaction is usually a reversible process, which should allow removal of the auxiliary after the reaction. Furthermore, the reaction is compatible with the use of an aqueous medium. Some Mannich reactions have even been reported to benefit from the use of water ". Finally, Lewis-acid catalysis of Mannich-type reactions in mixtures of organic solvents and water has been reported ". Hence, if both addition of the auxiliary and the subsequent Diels-Alder reaction benefit from Lewis-acid catalysis, the possibility arises of merging these steps into a one-pot procedure. 

To a 250-ml not-partitioned electrochemical cell, 135 ml of CH3CN, 15 ml ofHiO, 6.20 g of NaBr and 2.82 g of olefin ( ) is added. The mixture, kept at 2(f C, is electrolysed by using the same electrodes as of Example 1, but with a constant current density of 1.7 A being used,until through the cell 4,000 Coulombs have been passed. The reaction mixture is then processed as described in Example 4.2.56 g is obtained of ketone (III), with a yield of 83.2%, as computed relatively to the olefin (I) used as the starting material. 

The use of oximes as nucleophiles can be quite perplexing in view of the fact that nitrogen or oxygen may react. Alkylation of hydroxylamines can therefore be a very complex process which is largely dependent on the steric factors associated with the educts. Reproducible and predictable results are obtained in intramolecular reactions between oximes and electrophilic carbon atoms. Amides, halides, nitriles, and ketones have been used as electrophiles, and various heterocycles such as quinazoline N-oxide, benzodiayepines, and isoxazoles have been obtained in excellent yields under appropriate reaction conditions. 

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