1,3-propanedione

Recently, it has been shown that ultrasonic agitation during hydrogenation reactions over skeletal nickel can slow catalyst deactivation [122-124], Furthermore, ultrasonic waves can also significantly increase the reaction rate and selectivity of these reactions [123,124], Cavitations form in the liquid reaction medium because of the ultrasonic agitation, and subsequently collapse with intense localized temperature and pressure. It is these extreme conditions that affect the chemical reactions. Various reactions have been tested over skeletal catalysts, including xylose to xylitol, citral to citronellal and citronellol, cinnamaldehyde to benzenepropanol, and the enantioselective hydrogenation of 1-phenyl-1,2-propanedione. Ultrasound supported catalysis has been known for some time and is not peculiar to skeletal catalysts [125] however, research with skeletal catalysts is relatively recent and an active area. 

First of all, we may compare the values for this species and its lesser-methylated derivatives, the parent ethanedial and 1,2-propanedione dioximes, respectively. The former are only for the solid state. The differences for sequential methylation are the all but indistinguishable 36.2 and 36.1 kJmol and so we feel confident in this set of numbers. We also find that, at least for unstrained species, the gas phase olefin and aldehyde reactions in equations 29 and 30 are roughly endothermic by ca 4 kJmol . ... 

C9H10N4OS 1-Phenyl-1,2-propanedione-2-oxime thiosemicarbazone SpecQ-ophotometric Cu, Ni 31... 

Benzoxazines are commonly prepared from 2-aminophenols by reaction with 1,2-dielectrophiles . For example, the aminophenol 344 reacts with -ketoesters to give 345 (Scheme 187) <1961CB1664>, which is probably the result of initial rapid imine formation followed by lactonization. The reaction of 346 and l-phenyl-1,2-propanedione affords a mixture of the isomeric compounds 347 and 348 in a 3 2 ratio (Scheme 188) <1999M1481>. 

Diaminomaleonitrile (178) and l-phenyl-6-(triisopropylsilyl)-hexa-l,5-diyne-3,4-dione (PhC=CCOCOC=CSiPr 3) gave 5- phenylethynyl-6-(triisopropylsilyl)ethynyl-2,3-pyrazinedicarbonitrile (177) (AcOH, 20°C, 5 min 72%)403 the same diamine (178) and 3,3,3-trifluoro-1 -/Molyl-1,2-propanedione (F3CCOCOC6H4Me-p) gave 5-p-tolyl-6-trifluoromethyl-2, 3-pyrazinedicarbonitrile (179) (no details 74%) 807 and the same diamine (178) with / ,//-bis(bromomethyl)benzil (p-BrH2CC6H4COCOC6H4CH2Br-p) gave 5,6-bis[p-(bromomethyl)phenyl]-2,3-pyrazinedicarbonitrile (180)... 

This explanation was shown to be incorrect by investigation 95) of reactions of a number of a-diketones (benzil, biacetyl, 1-phenyl-1,2-propanedione) in the presence of olefins in oxygen saturated solutions. Slow consumption of diketone was observed with relatively rapid consumption of olefin and concomitant formation of epoxides, often in high yield. Many of the olefins which underwent this reaction do not form epoxides at all with singlet oxygen. For example, tetraphenylporphin-sensitized photooxygenation of tetramethylethylene afforded hydroperoxide 111 quantitatively while a biacetyl-sensitized reaction yielded the epoxide 112. Further, it was shown that the... 

Having obtained and described a suitable sample, the next stage is to analyse the material for the presence of cathinone and cathine. In addition to these drugs, other structurally similar compounds found in the C. edulis plant include norephedrine (3). It is well accepted that cathinone is converted into this compound by the process of enzymatic reduction. Furthermore, the oxidation product, 1-phenyl-1,2-propanedione (4), and the cathinone dimer, 3,6-dimethyl-2,5-diphenylpyrazine (5), may also be identified. These, however, are reported to form as artefacts of the isolation and analytical processes [6]. 

When poly(BOMA-co-MMA)s are subjected to UV irradiation in benzene solution, in the absence of any monomer, extensive degradation takes place [55,75], thus confirming the occurrence of a photocleavage mechanism. Similar results have been found [55] by irradiation in monomer-free benzene solution of the copolymers of 1-phenyl-1,2-propanedione-2-0-methacryloyloxime with MMA [poly(POMA-co-MMA)], although a much higher efficiency of main chain degradation is obtained (Scheme 18 and Table 14). 

C9H9F5Si trimethyl(pentafluorophenyl)silane 1206-46-8 443.15 38.450 1,2 16442 C9H9N02 1 -phenyl-1,2-propanedione-2-oxime 119-51-7 533.98 47.159 2... 

The methyl phenyl di-ketone, sometimes called 1-phenyl, 1,2-propanedione, which would be the di-ketone used for condensation with methylamine and the subsequent hydrogenation in the presence of a catalyst to produce ephedrine, is known, as are certain other diketones. 

Murzin et al. reported detailed studies of the hydrogenation of l-phenyl-1,2-propanedione (acetyl benzoyl), which has two carbonyl groups to give four possible stereoisomers by double hydrogenation [32]. A detailed theoretical analysis has also been reported for this substrate [33]. 

In general, 1.2-diones are good substrates for baker s yeast reduction, however, selectivity is low. In most cases a racemic mixture of the hydroxy ketones and the 1,2-diols is obtained. One exception Lo this rule is the reduction of 1-phenyl-1,2-propanedione to LS )-2-hydroxy-l -phenyl-propanone by baker s yeast in phosphate buffer at pH 5217. If the reaction is carried out with a large excess of yeast in distilled water, the (1 / ,2S)-1-phenyl-1,2-propanediol is obtained in high chemical and optical yield222. 

If the 1,2-diketone l-(l.3-dithian-2-yl)-1,2-propanedione (7) is treated with baker s yeast, the /i-keto group is reduced much faster than the a-keto group. Therefore, it is possible to obtain (S)-hydroxy ketone 8 (60% yield), by ensuring a short reaction time (2 h), and (S,S)-anti-diol 9 (82% yield), when the reaction time is longer (48 h)220. 

C.38) Propanal, 2-oxo-, 2-oxopropanal, pyruvaldehyde, 1,2-propanedione, acetylformaldehyde, methylglyoxal, pyruvic aldehyde (78-98-8] FEMA 2969... 

D.91) 1,2-Propanedione, 1-phenyl-, 1-phenylpropane-l,2-dione, methyl phenyl diketone, benzoyl methyl ketone, acetylbenzoyl [579-07-7] FEMA 3226... 

Propanedione, l-(5-methyl-2-furanyl)-, l-(5-methyl-2-furyl)propane-l,2-dione,... 

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