Acetaldehyde hydrogenation

The refinery design included the recovery of nonacid oxygenates in the Fischer-Tropsch aqueous product that are lighter boiling than water.30 The oxygenate chemicals recovered from the aqueous product included methanol (mainly from Fe-LTFT), ethanol (from Fe-HTFT, Fe-LTFT, and acetaldehyde hydrogenation), as well as mixed heavier alcohol and ketone streams. The carboxylic acids were not recovered and were processed with the wastewater. 

The constitution of phenylalanine was determined in 1882 by Erlen-meyer and Lipp, who synthesised it by Strecker s method from phenyl-acetaldehyde, hydrogen cyanide and ammopia —... 

Cysteine Mercaptoacetaldehyde, acetaldehyde, hydrogen sulphide, ammonia Important intermediates for meat-hke aromas... 

During conversion of ethanol by ADH to acetaldehyde, hydrogen ion is transferred from alcohol to the cofactor... 

The formation of 5,6-dihydro-2,4,6-trimethyl-l,3,5-dithiazine, 2,4,6-trimethyl-1,3,5-trithiane, and 3,5-d ime thy1-1,2,4-trithiolane by heating of acetaldehyde, hydrogen sulfide, and ammonia was outlined by Takken and coworkers (36) and is summarized in Figure 4. Under oxidative conditions, dialkyltrithiolanes are formed at low pH there is conversion to trialkyltrithianes at elevated temperature isomerization into trisulfides occurs, which compounds disproportionate into di and tetrasulfides and in the presence of ammonia, dithiazines are formed. These compounds and the conditions for their formation are of extreme importance for the production of desirable meat flavors. 

During conversion of ethanol to acetaldehyde, hydrogen ion is transferred from alcohol to the cofactor nicotinamide adenine dinucleotide (NAD+) to form NADH. As a net result, alcohol oxidation generates an excess of reducing equivalents in the liver, chiefly as NADH. The excess NADH production appears to underlie a number of metabolic disorders that accompany chronic alcoholism. 

Thiazoles and Thiazolines. Thiazoles and thiazolines provide nutty, roasted notes to meat flavors. These compounds can be formed by combining a diketone, such as 2,3-butanedione (diacetyl), with acetaldehyde, hydrogen sulfide, and ammonia (39). 2-Acetyl-2-... 

The mechanism of radiolysis of aqueous solutions has been studied by Jayson, Scholes, and Weiss. The amounts of acetaldehyde, hydrogen peroxide, hydrogen, and 2,3-butanediol were measured at various pH s and ethanol concentrations in oxygenated and in evacuated solutions. The yield of acetaldehyde is not independent of the concentration of ethanol. In oxygen, the curve for yield of acetaldehyde against concentration of ethanol flattens out at a concentration of 10 M, but the yield of acetaldehyde increases at higher concentrations. The range of concentration studied was 10 to 1 M ethanol. 

This condition is satisfied in the systems acetaldehyde-hydrogen-ethanol discussed in Example 4.2.3 and hydrogen-nitrogen-dichlorodifluoromethane used to illustrate Example 4.2.4. 

Methanol Acetone Acetaldehyde Hydrogen peroxide Glycerol... 

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). 

Ethyl lactate is produced by reacting acetaldehyde, hydrogen cyanide, and ethyl alcohol. 

Methyl-1,2,4-trithiane (346) can be prepared by chlorinating diethyl disulfide (344) to the dichloride (345) and letting it react with (342) (Scheme 51) <74MI 620-0i>. The reaction of acetaldehyde, hydrogen sulfide and (342) also affords (346) [Pg.897]

Figure 1 Formation of selected compounds from interactions between acetaldehyde, hydrogen sulfide, methanethiol and ammonia (5,28) (Compounds identified in YE aroma are indicated by ( ).)...

Accordingly, methanol reacts with the metal acetylide to form metal methoxide and acetylene. The methoxide decomposes to formaldehyde, whieh undergoes a condensation reaction to yield acetaldehyde. Hydrogenation of the acetaldehyde yields ethanol Similar aldol eondensation reaetions occur among the aldehydes with carbon number 1 to yield hi er alcohols. 

We observe that besides the ethanol desorption profile (a), there are other profiles related to the formation of water, acetaldehyde, hydrogen, CO, and methane at different temperature ranges (Fig. 6.18b). This suggests dehydrogenation and decomposition reactions of ethanol. Dehydrogenation and decomposition reactions occur on the metallic sites while dehydration on the support [30]. 

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