Water reaction with carbonyls

Wittig reactions. These reagents are water soluble. Product isolation from their reaction with carbonyl compounds is also facilitated as the phosphine oxide can be removed by base. 

The rate of chain scission is increased in the presence of active hydrogen (e.g., water), probably due to reaction with carbonyl oxides to form reactive hydroperoxides. Crosslinking products may also be formed, especially with rubbers containing disubstituted double bonds (e.g., polybutadiene, BR, and styrene-butadiene rubber, SBR). 

The zwitterion (6) can react with protic solvents to produce a variety of products. Reaction with water yields a transient hydroperoxy alcohol (10) that can dehydrate to a carboxyUc acid or spHt out H2O2 to form a carbonyl compound (aldehyde or ketone, R2CO). In alcohoHc media, the product is an isolable hydroperoxy ether (11) that can be hydrolyzed or reduced (with (CH O) or (CH2)2S) to a carbonyl compound. Reductive amination of (11) over Raney nickel produces amides and amines (64). Reaction of the zwitterion with a carboxyUc acid to form a hydroperoxy ester (12) is commercially important because it can be oxidized to other acids, RCOOH and R COOH. Reaction of zwitterion with HCN produces a-hydroxy nitriles that can be hydrolyzed to a-hydroxy carboxyUc acids. Carboxylates are obtained with H2O2/OH (65). The zwitterion can be reduced during the course of the reaction by tetracyanoethylene to produce its epoxide (66). 

Reactions of the Side Chain. Benzyl chloride is hydrolyzed slowly by boiling water and more rapidly at elevated temperature and pressure in the presence of alkaHes (11). Reaction with aqueous sodium cyanide, preferably in the presence of a quaternary ammonium chloride, produces phenylacetonitrile [140-29-4] in high yield (12). The presence of a lower molecular-weight alcohol gives faster rates and higher yields. In the presence of suitable catalysts benzyl chloride reacts with carbon monoxide to produce phenylacetic acid [103-82-2] (13—15). With different catalyst systems in the presence of calcium hydroxide, double carbonylation to phenylpymvic acid [156-06-9] occurs (16). Benzyl esters are formed by heating benzyl chloride with the sodium salts of acids benzyl ethers by reaction with sodium alkoxides. The ease of ether formation is improved by the use of phase-transfer catalysts (17) (see Catalysis, phase-thansfer). 

The initial step is the protonation of the aldehyde—e.g. formaldehyde—at the carbonyl oxygen. The hydroxycarbenium ion 6 is thus formed as reactive species, which reacts as electrophile with the carbon-carbon double bond of the olefinic substrate by formation of a carbenium ion species 7. A subsequent loss of a proton from 7 leads to formation of an allylic alcohol 4, while reaction with water, followed by loss of a proton, leads to formation of a 1,3-diol 3 " ... 

The reaction with a carbonyl substrate 3 is similar to a Grignard reaction. Hydrolytic workup then yields the /3-hydroxy ester 4. Sometimes product 4 easily eliminates water to yield directly an o ,/3-unsaturated ester. 

Dimedone reacts with carbonyl compounds with the elimination of water yielding the condensation product [1]. The reaction is specific for ketoses aldoses do not react or only weakly [6],... 

The Mannich condensation has traditionally been carried out in the presence of water as a three-component condensation involving a carbonyl compound (or related carbon nucleophile), formaldehyde, and a primary or secondary amine. The initial step is a condensation between the latter two reactants to form a mono- or dialkyl(methylene)ammonium ion which subsequently serves as the electrophilic partner in the reaction. With unsymmetrical ketones aminomethylation generally occurs at both positions to give mixtures of isomeric 3-amino ketones. The ratio of the isomers depends strongly on the structure of the ketone, and the more highly branched (3-amino ketone usually predominates. 

Ab initio molecular orbital calculations are being used to study the reactions of anionic nucleophiles with carbonyl compounds in the gas phase. A rich variety of energy surfaces is found as shown here for reactions of hydroxide ion with methyl formate and formaldehyde, chloride ion with formyl and acetyl chloride, and fluoride ion with formyl fluoride. Extension of these investigations to determine the influence of solvation on the energy profiles is also underway the statistical mechanics approach is outlined and illustrated by results from Monte Carlo simulations for the addition of hydroxide ion to formaldehyde in water. 

Alternatively one can make use of No Barrier Theory (NBT), which allows calculation of the free energy of activation for such reactions with no need for an empirical intrinsic barrier. This approach treats a real chemical reaction as a result of several simple processes for each of which the energy would be a quadratic function of a suitable reaction coordinate. This allows interpolation of the reaction hypersurface a search for the lowest saddle point gives the free energy of activation. This method has been applied to enolate formation, ketene hydration, carbonyl hydration, decarboxylation, and the addition of water to carbocations. ... 

It can also be done by in situ generation of other types of electrophiles. For example, good yields of /V-acyl a-amino acids are formed in a process in which an amide and aldehyde combine to generate a carbinolamide and, presumably, an acyliminium ion. The organopalladium intermediate is then carbonylated prior to reaction with water.254... 

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