2,3-Pentanedione, reaction with ammonium sulfide

Reaction of a-Dicarbonyls (2,3-Butanedione and 2,3-Pentanedione) with Ammonium Sulfide... 

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. 

In the reaction of 2,3-butanedione and ammonium sulfide at 25 °C, quantitation of volatile compoimds identified in the reaction is summarized in Table II. A pair of interesting intermediate compounds, 5-hydroxy-3-thiazolines, were tentatively identified by GC/MS-EI. 5-Hydroxy-2,4,5-trimethyl-3-thiazolines have been separated and identified by GC/MS-EI and NMR in the early study of volatile flavor conq)ounds of yeast extracts (S). They were also found in the reaction of 2,3-butanedione or 2,3-pentanedione with acetaldehyde, hydrogen sulfide and ammonia (2). 

Takken (2) identified thiazoles and 3-thiazolines from the reaction of 2,3-butanedione and 2,3-pentanedione with ammonia, acetaldehyde and hydrogen sulfide at 20 °C. Study of tetramethylpyrazine (5) also showed that it can be readily formed in 3-hydroxy-2-butanone and ammonia model reaction at 22 C. Recent study of the model reaction of 3-hydroxy-2-butanone and ammonium acetate at low temperature revealed an interesting intermediate compound, 2-(l-hydroxyethyl)-2,3,4-trimethyl-3-oxazoline, along with 2,4,5-trimethyloxazole, 2,4,5-trimethyl-3-oxazoline, and tetramethylpyrazine were isolated and identified 4,5). We hypothesized that with the introducing of H2S, replacement of oxygen by sulfur could happen and sulfur-containing heterocyclic compoimds such as thiazoles and thiazolines could be formed along with oxazoles, oxazolines and pyrazines. 

---

See also in sourсe #XX -- [ , ]

---