2-Propanone isolation

Chemically, wood tar is a complex mixture that contains at least 200 individual compounds, among which the foUowing have been isolated (1) 2-methoxyphenol, 2-methoxy-4-ethylphenol, 5-meth5i-2-methoxyphenol, 2,6-x5ienol, butyric acid, crotonic acid, 1-hydroxy-2-propanone, butyrolactone, 2-methyl-3-hydroxy-4JT-pyran-4-one, 2-methyl-2-propenal, methyl ethyl ketone, methyl isopropyl ketone, methyl furyl ketone, and 2-hydroxy-3-methyl-2-cyclopenten-l-one. 

Amino 2 deoxy d glucose, conversion of hydrochloride to 2 acetamido-2 deoxy d glucose, 46, 2 l-(Ammomcthyl) cycloheptanol, 46, 31 2 Amino 2 methyl 1 propanol in isolation of levopimanc acid 45, 64 c-Amino p nitrobiphenyl, by nitration of o aminobiphenyl, 46, 86 from o,p dimtrobiphenyl, 46, 88 Amino 2 propanone, semicarbazone... 

For preparative purposes fermenting baker s yeast (Saccharomyces cerevisiae) is commonly used instead of a purified enzyme preparation. However, isolated pyruvate decarboxylates can also be used30. In this context, the most important substrate is benzaldehyde31 which is converted by n-glucosc fermenting yeast to (7 )-l-hydroxy-l-phenyl-2-propanone. This conversion has gained considerable industrial importance because ( )-l-hydroxy-1-phenyl-2-propanonc is an important precursor for the synthesis of (-)-cphedrin. 

The reaction of 3-nitro-l,2,4-triazole with propanone 327 results in a complex reaction mixture, where oxazolo[3,2-7][ 1,2,4] triazole 328 is detected and isolated (unreported yield) (Equation 57) <2001RJOC1217>. 

Amino-2-methyl-l-piopanol in isolation of levopimaric acid, 45, 64 Amino-2-propanone, semicarbazone HYDROCHLORIDE, 46,1 Ammonium chlorophenyldithiocarba-mate, 46, 21... 

Electrochemical reduction of a,a -dibromoketones affords the unstable cyclo-propanone, which is in equlibrium with the dipolar intermediate 22. The cyclopro-panone hemiacetal is isolated in yields of 40 - 85 % from reaction in acetonitrile and methanol at -20 °C [99], The dipolar form can be trapped in a cycloaddition process with furan [100], Reaction with acetic acid leads to the a-acetoxy-ketone.[101]. Unstable three membered heterocyclic rings are intermediate in the reduction of sulphur and phosphorus linked dibromo compounds 23. In these reactions, the heteroatom is extruded leaving ci - and trans-stilbenes as the isolated products [102,103],... 

From the base-catalyzed degradation of D-fructose (pH 8.0), Shaw and coworkers147 identified 18 compounds, none of which was (a) isomeric with the starting material, or (b) a simple dehydration product. Among the products, the hydroxy-2-butanones and 1-hydroxy-2-propanone (acetol) were shown to participate in forming the carbo-cyclic products identified, but the mechanism of their formation was not elucidated. Several furan derivatives were isolated, but no lactic acid was isolated. In a similar study but with weak acid,41 most of the products were formed by a combination of enolization and dehydration steps, with little fragmentation. 

The isolation of uridine 5 -(l,3-dihydroxy-2-propanone pyrophosphate) from a Pneumococcus strain has been reported.202... 

The equilibrium for hydrate formation depends both on steric and electrical factors. Methanal is 99.99 % hydrated in aqueous solution, ethanal is 58 % hydrated, and 2-propanone is not hydrated significantly. The hydrates seldom can be isolated because they readily revert to the parent aldehyde. The only stable crystalline hydrates known are those having strongly electronegative groups associated with the carbonyl (see Section 15-7). 

The optical isomers of DOM have been prepared in two ways. The racemic base has been resolved as the ortho-nitrotartranilic acid salt by recrystallization from EtOH. The (+) acid provides the (+) or S isomer of DOM preferentially. Also, the above-mentioned l-(2,5-dimethoxy-4-methylphenyl)-2-propanone can be reductively aminated with optically active alpha-methyl benzylamine with Raney Nickel. This amine is isolated and purified by recrystallization of the hydrochloride salt. When optically pure, the benzyl group was removed by hydrogenolysis with palladium on carbon. The mp of either of the optical isomers, as the hydrochloride salts, was 204-205 °C. 

Many other compounds have been identified as products of the sugar-amino acid reaction. Amongst these are 2,3-butanedione,195 formaldehyde,196 pyruvaldehyde,20,195, 247, 248 3-hydroxy-2-butanone,248 hydroxy-2-propanone,248 and acetaldehyde.73 Imidazoles,196, 249-251 especially 4(5)-methylimidazole, have also been isolated from the reaction under mild conditions, and could have been formed from a-hydroxy ketones or aldehydes plus amino compounds. Following the early identification247 of pyru-valdehyde as a product of the Maillard reaction, much work was done in an attempt to show that this reactive compound plays a major role in the reaction,249 262 254 but, that this is so is by no means certain.7... 

We have also observed that the silylation of the enolate derived from 2-phe-nylselanylpentan-3-one, generated under the same conditions, always afforded the a,ci -bis(phenylselanyl) ketone as well as the two regioisomeric enoxysilanes [40] (Scheme 35, reaction 1). Treatment of this ketone with f-BuOK in f-BuOH gave exclusively the a,ci -bis(phenylselanyl)pentanone [41] (Scheme 35, reaction 2). A selenophilic reaction occurred between the phenylselanylpro-panone and its selenium-stabilized enolate. The enoxysilane derived from 1,1-bis (phenylselanyl)propanone was isolated albeit in poor yield (11%), besides the l,l,l-tris(phenylselanyl)propanone and the unreacted phenylselanyl-propanone [42] (Scheme 35, reaction 3). 

Acyclic a-hydroxy ketones of high enantiomeric purity can be prepared by choice of the appropriate conditions and (camphorylsulfonyl)oxaziridine reagent, for example, treatment of deoxy-benzoin (159a) with NaHMDS followed by (+)-(114) at —78°C affords (+ )-(S)-benzoin (160) in 95% ee and 88% isolated yield (Scheme 29) <89JOC202i, 90JA6679). Similarly, (—)-(S)-2-hydroxy-1 -phenyl-1-propanone (161) is produced in 95% ee by hydroxylation of the lithium enolate of... 

The most important reaction of allene oxides is thermal isomerization to the valence tautomeric cyclopropanones. Many reactions pass via this process, but the cyclo-propanones are not usually isolated except in cases of kinetic stabilization. ... 

A dehydration of this type has actually been observed as a side reaction of a Lobry de Bruyn-Alberda van Ekenstein transformation in a very simple system. Thus, in experiments with the DL-glycerose-l,3-dihy-droxy-2-propanone isomerization in acetate, formate, and trimethylacetate buffers, pyruvaldehyde appeared in the reaction mixtures. (The formation of pyruvaldehyde from l,3-dihydroxy-2-propanone- and dl-glycerose-mineral acid mixtures had been observed much earlier.) Since these experiments in acidic buffers established that this reaction is subject to general acid and base catalysis, pyruvaldehyde must be formed in alkaline mixtures also. The results of Wohl s and Evans and Hass s experiments with DL-glycerose in alkaline solutions containing phenyl-hydrazine, in which pyruvaldehyde phenylosazone was isolated, support this view. 

The first stage, involving the transfer of active glycolaldehyde, can be accomplished in the laboratory by use of spinach or rat-liver transketolase, and the products isolated and characterized as the barium salt and 2,7-anhydride, respectively. The second stage is catalyzed by liver or yeast transaldolase and is believed to involve the enzymic transfer of a 1,3-di-hydroxy-2-propanone residue sedoheptulose 7-phosphate and D-fructose... 

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