Propanone l-hydroxy

In this thiamine pyrophosphate-mediated process, ben2aldehyde (29), added to fermenting yeast, reacts with acetaldehyde (qv) (30), generated from glucose by the biocatalyst, to yield (R)-l-phen5l-l-hydroxy-2-propanone (31). The en2ymatically induced chiral center of (31) helps in the asymmetric reductive (chemical) condensation with methylamine to yield (lR,23)-ephedrine [299-42-3] (32). Substituted ben2aldehyde derivatives react in the same manner (80). 

The reaction of ethyl acetoacetate with simple hydroxy ketones has been compared with the corresponding reactions of the ketoses. The results obtained with l-hydroxy-2-propanone and 3-hydroxy-2-butanone, under the same experimental conditions as with D-fructose, establish a parallel between these reactions. However, as in the case of the aldoses, the yield is greater for these simpler hydroxy ketones than for the ketoses.9 The resultant esters, (XV and XVI), were obtained in the form of sirups, but the free acids, (XVII and XVIII), and their phenacyl esters are crystalline. The acids were shown to be identical with those of known structure described in the literature.9... 

Chemically, wood tar is a complex mixture that contains at least 200 individual compounds, among which the following have been isolated (1) 2-methoxyphenol, 2-methoxy-4-ethylphenol, 5-methji-2-methoxyphenol, 2,6-xylenol, butyric acid, crotonic acid, l-hydroxy-2-propanone, butyrolactone, 2-methyl-3-hydroxy-4H-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. 

Ketones acetol (l-hydroxy-2-propanone), cyclo pentanone 1-5... 

Acetol l-hydroxy-2-propanone HO —CH2CCHJ Acetonitrile cyanomethane an organic solvent CH3C=n... 

Aqueous mixtures containing a-hydroxyketones (3-hydroxy-2-butanone, l-hydroxy-2-propanone, l-hydroxy-2-butanone) or a-dicarbonyls (2,3-butanedione, 2,3-pentanedione) and ammonium sulfide were reacted at 25 °C for 2 hr. Among the heterocyclic flavor compounds formed were oxazoles, oxazolines, thiazoles, thiazolines and pyrazines. 2-(l-Hydroxyalkyl)-3-oxazolines and 2-( 1 -hydroxyalkyl)-3-thiazolines were major intermediate compounds identified in a-hydroxyketone systems and on the other hand, 5-hydroxy-3-oxazolines and 5-hydroxy-3-thiazolines were proposed as intermediate compounds in o-dicarbonyl systems. 

To test the volatile heterocyclic conq)ounds formation under low temperature condition, 0.01 mol of one of the following carbonyl compounds including a-hydroxyketones (3-hydroxy-2-butanone, 0.88 g l-hydroxy-2-propanone, 0.74 g l-hydroxy-2-butanone 0.88g) and a-dicarbonyls (2,3-butanedione, 0.86 g 2,3-pentanedione 1.00 g) and 0.02 mol of ammonium sulfide (20% wt/wt solution in water) were dissolved in 25 mL distilled water and reacted at 25°C for 2 hours. Immediately follow the reactions, the mixtures were cooled and extracted with methylene chloride three times, dried over anhydrous sodium sulfate, and then concentrated under a stream of N2 for further GC and GC/MS analyses. 

Reaction of a-Hydroxyketones (3-Hydroxy-2-butanone, l-Hydroxy-2-propanone and l-Hydroxy-3-butanone) with Anunonium Sulflde... 

In the studies of the reactions of l-hydroxy-2-propanone and l-hydroxy-2-butanone and ammonium sulfide, despite four possible intermediates were predicted, only two intermediate compounds were tentatively identified by GC/MS in our study. The mass spectral data of these compounds showed very distinctive base peak p attem (Table I). These results agreed with results from previous study of five different 2-alkyl-2,4,5-trimethyl-2,5-dihydrooxazolines (7) which showed same mass spectral fragmentation pattern (m/z = 112) of same types of intermediate con5>ounds. Further study of GC/MS-CI results suggested their molecular weights and as the results, they were tentatively identified as 2-(1 -hydroxymethyl)-2,4-dimethyl-3-oxazoline, 2-( 1 -hydroxymethyl)-2,4-... 

Proposed reaction mechanism of l-hydroxy-2-propanone or l-hydroxy-2-butanone with ammonium sulfide is shown in Figure 5. 2-Iminoalcohols, which were derived from the reaction of ammonia and a-hydroxyketones, were condensed with another molecule of a-hydroxyketone to form 2-(l-hydroxymethyl)-2,4-dialkyl-3-oxazolines. The substitution of -OH group with -SH group resulted in the formation of 2-(l-hydroxyemthyl)-2,4-dialkyl-3-thiazolines. No 2-(l-mercaptomethyl)-substituted isomers were found in either reaction. Upon heating, these intermediates were further converted to the corresponding oxazolines, oxazoles, thiazolines and thiazoles. 

Figure 5. Proposed reaction mechanism of l-hydroxy 2-propanone or 1-hydroxy-2-butanone with ammonium sulfide.

Lobry de Bruyn-Alberda van Ekenstein isomerizations between related compounds has since been expanded to include isomerizations of 2-hy-droxybutyrophenone, l-(4-chlorophenyl)-l-hydroxy-2-propanone, and 2-hydroxy-l-phenyl-1,4-pentanedioneJ ... 

The saccharinic acid was next prepared in 32 % yield from the halogen acid (XLIII) by treatment with silver oxide, but this approach was abandoned when good results were obtained from the acetol-form-ester. Reaction of l-chloro-2-propanone (XLVII) with sodium formate produced the monoformate of l-hydroxy-2-propanone (XLIX) which, through the addition of hydrogen cyanide and hydrolysis of the resulting cyanohydrin of l-hydroxy-2-propanone (L), yielded the desired racemic saccharinic acid (Vab). 

Another feature common to all hexoses is their fragmentation to trioses and related products (such as lactic acid, l-hydroxy-2-propanone, and pyruvaldehyde). l-Hydroxy-2-propanone is formed by heating a solution of D-fructose in potassium acid phosphate buffer solution of pH 6.7 it was proposed that an intermediary 3,4-enediol (s) rearranges to a /3-diketone, which yields (t) by fragmentation of the molecule. Studies by Wolfrom and Schumacher and by Blair and Sowden showed that this mechanism, followed by recombination and aldolization, accounts for some of the observed products. The identification of L-a 2/io-hexulose and DL-a yZo-hexulose was conclusive in this respect, but deuterium studies by Sowden and Thompson proved the minor role of this recombination mechanism in the transformations. 

Aliphatic a-hydroxy ketones are easily reduced by baker s yeast to yield the (7 )-configurated 1,2-diols. The reduction of l-hydroxy-2-propanone to (/ )- ,2-propanediol is still of preparative interest227,232. The corresponding a-hydroxy ketones with higher alkyl chain length are also reduced in high enantioselectivity with moderate to high yield. 

As l-hydroxy-2-propanone and 2-hydroxypropionaldehyde are pol-arographically active compounds, they can undergo further reduction, as shown in Scheme 17. 

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