Carbonylative aldehyde

The reaction of a carbonyl (aldehyde or ketone) with a base produces an enolate ion (a nucleophile). This nucleophile attacks any electrophile. What happens when you add a base to a carbonyl with no electrophile present ... 

Electron-withdrawing substituents such as cyano and carbonyl (aldehyde, ketone, acid, or ester) facilitate the attack of an anionic species by decreasing the electron density on the double bond ... 

Methylglyoxal and other a-carbonyl aldehydes MGLY Peroxy radicals formed from ketone, KET KETP... 

Ketones were also reacted under these conditions, leading to tertiary ethers. Thus, by mixing equimolar quantities of a carbonyl (aldehyde or ketone), allyl-silane and a silylated alcohol, followed by the addition of a catalytic amount of TMSOTf, homoallylic ethers can be obtain in good yields via a three-component coupling reaction (Scheme 13.22). 

Dimethyltitanocene (213), called the Petasis reagent, can be used for alkenation of carbonyls (aldehydes, ketones, esters, thioesters and lactones). This reagent is prepared more easily than the Tebbe reagent by the reaction of titanocene dichloride with MeLi. However, this reagent may not be a carbene complex and its reaction may be explained as a nucleophilic attack of the methyl group at the carbonyl [67], Alkenylsilanes are prepared from carbonyl compounds. Tri(trimethylsilyl)titanacyclobutene (216), as a... 

Donor carbonyl Aldehyde Product Yield (%) syn/anti ee (%) Ref. 

Food, flavors consist of numerous compounds, none of which alone is characteristic of specific food. Classes of compounds which emcompass food flavors are - hydrocarbons (aliphatic, ali-cyclic, aromatic) carbonyls (aldehydes, ketones) carboxylic acids, esters, imides, anhydrides alcohols, phenols, ethers alkylamines, alkylimines aliphatic sulfur compounds (thiols, mono-, di- and tri-sulfides) nitrogen heterocyclics (pyrroles, pyrazines, pyridines) sulfur heterocylics (thiophenes, thiazoles, trithiolane, thialidine) and oxygen-heterocyclics (lactone, pyrone, furan). Discussion will be limited to striking developments in heterocyclics. 

When cellulose is exposed to the unlimited supply of oxygen present as 21% of the air, unstable peroxide radicals form. In the autocatalytic reaction of cellulose oxidation, decomposition of peroxide forms cellulose radicals that react with oxygen to form R02- radicals. These radicals attack other cellulose molecules to form oxycelluloses (carbonyl, aldehyde, and carboxyl acid groups) along with more cellulose free radicals (34). 

Loss of Flavor Compounds in UHT Processed Cream. Table 1 shows the concentrations of flavor compounds in UHT processed cream packaged in Tetra Brik packages over 12 mo storage. The concentration of flavor compounds represents an average of four processes. Butanal concentration decreased 50%, aldehydes (C -C,0) decreased 75-85% and total carbonyls (aldehydes, Ketones, enals, dienals, ketoacids, ketoglycerides, and dicarbonyls) decreased 97%. 

Sugar molecules are predictably reactive due to their polyfunctional character, especially the presence of a carbonyl, aldehyde or ketone radical. A certain number of these reactions play a role in winemaking, especially in assaying sugar levels in wine. Addition reactions with sulfur dioxide are described elsewhere (Volume 1, Sections 8.3.2 and 8.4.4). 

Due to the presence of carbonyl, aldehyde or ketone radicals, sugars are capable of addition reactions with nucleophilic reagents such as phenylhydrazine (C6H5-NH-NH2). The addition of three phenylhydrazine molecules to an aldose (Figure 3.12) leads to the formation of osazone, a crystallized product with specific physicochemical characteristics, especially its melting point. This makes it possible to identify the corresponding sugar. 

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