Ketones reaction with bisulfite

The enhanced reactivity of fluoroalkyl ketones is also manifested in the failure to stop the reaction with hydrogen cyanide at the stage of cyanohydrins Instead, oxazohdinones or dioxolanones are formed (equation 11) If, however, the reaction IS conducted under basic conditions with sodium bisulfite and sodium cyanide, the desired cyanohydrin can be prepared [ll ... 

The reversibility of the reaction makes bisulfite compounds useful intermediates in the synthesis of oilier adducts from aldehydes and ketones. For example, one practical method for making cyanohydrins involves bisulfite compounds. The famous practical book Vogel3 suggests reacting acetone first with sodium bisulfite and then with sodium cyanide to give a good yield (70%) of the cyanohydrin. 

Rather than direct reaction with an aldehyde or ketone, the bisulfite addition product is often treated with cyanide. The addition is nucleophilic and the actual nucleophile is CN, so the reaction rate is increased by the addition of base. " " This was demonstrated by Lap worth in 1903, and consequently this was one of the first organic mechanisms to be known. This method is especially useful for aromatic aldehydes, since it avoids competition from the benzoin condensation. If desired, it is possible to hydrolyze the cyanohydrin in situ to the corresponding a-hydroxy acid. This reaction is important in the Kiliani-Fischer method of extending the carbon chain of a sugar. 

In an acidic environment, it is protonated, and occurs mainly as sulfurous acid. In an alkaline environment, the protons dissociate, and it occurs mainly as bisulfite. Sulfurous acid is in an equilibrium with sulfur dioxide, which can leave a solution of water to enter atmosphere. The toxic effects of sulfite arise from its reactions with sulfhydryl groups, aldehyde groups, and ketones. Sulfite can also react with enz5nne-bound NAD and FAD. It is well known that the sulfite added to foods can react with the thiamin in the food, destroying this vitamin. The reaction of sulfite with sulfhydryl groups (R— SH) results in its conversion to an S-sulfonate group (R—S—SO3-). 

The reaction is carried out by mixing the aldehyde or ketone with a concentrated aqueous solution of sodium bisulfite the product separates as a crystalline solid. Ketones containing bulky groups usually fail to react with bisulfite, presumably for steric reasons. 

BASF patented the hydroformylation of 2,6-dimethylhept-l-en-6-ol, obtainable from the corresponding ketone via Grignard reaction (Scheme 6.41) [133]. The reaction with syngas was performed in the 1 kg scale with an unmodified Rh catalyst to afford 3,7-dimethyloctan-l-al-7-ol (hydroxycitronellal) in 90% yield. The use of a PPhg-modified catalyst did not improve this result. Usually, hydroxycitronellal is extracted from ethereal oils or can be alternatively produced by the hydration of citronellal bisulfite in an acidic medium [134]. The annual production is about 11001 [135]. The oil has a sweet floral scent, which is reminiscent of lilac, lily, lily of the valley, or lime. By the same protocol, also related hydroxy aldehydes with other interesting olfactory properties become accessible. 

Nucleophilic addition reactions are mainly of technical interest in the context of further reactions at C=0 groups present in aldehydes or ketones. The electronic nature of a carbonyl group is characterized by the greater electronegativity of the oxygen atom compared to the carbon atom. Thus, the carbon atom is the preferred place of nucleophilic attack, that is, of reaction with an electron-rich reagent. Scheme 2.2.12 gives as an example the technically important cyanohydrin reaction. Other important nucleophilic additions are the reaction of carbonyl compounds with alcohols and water, bisulfite and metal hydrides. 

Reactions with Aldehydes and Ketones. Aromatic or a, -unsaturated aldehydes or their bisulfite addition compounds are converted to gem-dichlorides by treatment with SOCI2, either neat or in an inert solvent such as nitromethane (eq 1This process is readily catalyzed by RMPA." Thionyl chloride may be preferred over the more commonly used PCI5 if removal of byproducts is problematic with the latter reagent. 

Anyway, one has the P2P/crap oil, right Right. Next one makes a saturated sodium bisulfite solution by dissolving as much sodium bisulfite as will dissolve in a given amount of water (say, lOOOmL). Now one adds the MD-P2P oil into some of the saturated solution and stirs for 30 minutes. The temperature of the reaction will rise and a big old mass of P2P crystals will form. People often say that the crystals look like chicken fat. Those crystals formed because the bisulfite from the sodium bisulfite latched onto the ketone of the P2P to form a precipitate. And since the P2P is probably the only oil component with a ketone, it is gonna be the only thing of any consequence that crystallizes. 

Many of these reactions are reversible, and for the stronger nucleophiles they usually proceed the fastest. Typical examples are the addition of ammonia, amines, phosphines, and bisulfite. Alkaline conditions permit the addition of mercaptans, sulfides, ketones, nitroalkanes, and alcohols to acrylamide. Good examples of alcohol reactions are those involving polymeric alcohols such as poly(vinyl alcohol), cellulose, and starch. The alkaline conditions employed with these reactions result in partial hydrolysis of the amide, yielding mixed carbamojdethyl and carboxyethyl products. 

Cyclohexanone shows most of the typical reactions of aUphatic ketones. It reacts with hydroxjiamine, phenyUiydrazine, semicarbazide, Grignard reagents, hydrogen cyanide, sodium bisulfite, etc, to form the usual addition products, and it undergoes the various condensation reactions that are typical of ketones having cx-methylene groups. Reduction converts cyclohexanone to cyclohexanol or cyclohexane, and oxidation with nitric acid converts cyclohexanone almost quantitatively to adipic acid. 

In a 3-I. flask are placed a solution of 184 g. (4.6 moles) of sodium hydroxide in 300-400 cc. of water and sufficient ice to make the total volume about 1500 cc. Chlorine is passed into the solution, keeping the temperature below 0° by means of a salt-ice bath, until the solution is neutral to litmus (Note i). After the addition of a solution of 34 g. of sodium hydroxide in 50 cc. of water, the flask is supported by a clamp and equipped with a thermometer and an efficient stirrer. The solution is warmed to 55°, and 85 g. (0.5 mole) of methyl d-naphthyl ketone (Note 2) is added. The mixture is vigorously stirred and, after the exothermic reaction commences, the temperature is kept at 60-70° (Note 3) by frequent cooling in an ice bath until the temperature no longer tends to rise. This requires thirty to forty minutes. The solution is stirred for thirty minutes longer and then the excess hypochlorite is destroyed by adding a solution of 50 g. of sodium bisulfite in 200 cc. of water (Note 4). After cooling to room temperature, the reaction mixture is transferred to a 4-I. beaker and carefully acidified with 200 cc. 

Bisulfite addition products are formed from aldehydes, methyl ketones, cyclic ketones (generally seven-membered and smaller rings), a-keto esters, and isocyanates, upon treatment with sodium bisulfite. Most other ketones do not undergo the reaction, probably for steric reasons. The reaction is reversible (by treatment of the addition product with either acid or base ) and is useful for the purification of the starting compounds, since the addition products are soluble in water and many of the impurities are not. ... 

---