Ketones, catalytic

For most laboratory scale reductions of aldehydes and ketones catalytic hydro genation has been replaced by methods based on metal hydride reducing agents The two most common reagents are sodium borohydride and lithium aluminum hydride... 

The oxidation to the enone was realized with catalytic amounts of tetra-n-propylammonium perruthenate (TPAP)21 (46), which is a mild oxidant for conversion of multifunctionalized alcohols to aldehydes or ketones. Catalytic TPAP oxidations are carried out in the presence of stoichiometric or excess A-methylmorpholine-A-oxide (NMO)22 (47) as cooxidant. Other common reagents for oxidation of alcohols are e.g. DMS0/C202C1223, Dess-Martin periodinane24, PCC25, PDC26 or the Jones reagent27. 

This most versatile of amine syntheses can be used to make primary, secondary or tertiary amines providing only that an imine can be formed with an aldehyde or ketone. But tertiary carbon atoms cannot be joined to nitrogen by reductive amination as a tertiary carbon atom cannot have a carbonyl group. The method works by selective reduction of the imine 28 in the presence of the aldehyde 27 or ketone. Catalytic hydrogenation reduces the imine 28 preferentially as the C=N bond of the imine is weaker than the C—O bond of the aldehyde or ketone. 

Methyldihydrocodeine [xxn] on heating with thionyl chloride is dehydrated to 6-methyldesoxycodeine-C [xxm] phosphorus penta-chloride effects chlorination in position 1 in addition to dehydration. 6-methyldesoxycodeine-C is non-phenolic and gives no formaldehyde on ozonolysis the ozonide on treatment with iodine and alkali yields iodoform, indicating formation of a methyl ketone. Catalytic reduction of [xxm] gives 6-methyltetrahydrodesoxycodeine [xxiv] [16]. 

Alkylphosphonate esters. The carbanion generated from dechlorination with BuLi condenses with aldehydes (and some ketones). Catalytic hydrogenation of the (chlorovinyl)phosphonate products affords phosphonates. 

Rose Bengal xanthene dye photosensitizer, 277 Ruthenium, dihydrotetrakis(triphenylphosphine)- double bond shift in alkenes, 270 Ruthenium(2 +), chiral binap complexes asym. hydrogenation with, 102-103, 325-326 Ruthenium(8 +) oxide oxidation with of alcohols to ketones (catalytic), 267 of alkynes to 1,2-diones (catalytic), 117, 132 of ethers to esters, 118, 134-135... 

Similarly, VOCs adsorbed from air samples onto Tenax or activated charcoal can be sealed and stored for several months prior to analysis. Losses have been reported only with cyclic and aliphatic ketones (catalytic oxidation) and esters (hydrolysis) [ 14.5]. For these groups of substances, losses approach a maximum of 20 % after a four-week storage period. No losses were observed with benzene, toluene, and xylenes over a 24-month storage period [146]. Samples containing analytes of lower volatility can be stored in suitable containers for a few days at -i4 °C, and for several months deep-frozen at -18 °C or lower. 

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