From ketones Hydration

Oxo Ion Salts. Salts of 0x0 ions, eg, nitrate, sulfate, perchlorate, hydroxide, iodate, phosphate, and oxalate, are readily obtained from aqueous solution. Thorium nitrate is readily formed by dissolution of thorium hydroxide in nitric acid from which, depending on the pH of solution, crystalline Th(N02)4 5H20 [33088-17 ] or Th(N02)4 4H20 [33088-16-3] can be obtained (23). Thorium nitrate is very soluble in water and in a host of oxygen-containing organic solvents, including alcohols, ethers, esters, and ketones. Hydrated thorium sulfate, Th(S0 2 H20, where n = 9, 8, 6, or 4, is... 

A solution of the 3-ketone hydrate (0.15 g) in acetone- -heptane is heated to boiling. After the acetone has been boiled off, a trace of concentrated hydrochloric acid is added to the -heptane solution and boiled for an additional 2 min. After cooling, the resulting crystals are collected by filtration, washed with dry -heptane and dried in vacuo overnight. Recrystallization from dry -heptane gives 17 -hydroxy-4,4-difluoroestr-5-en-3-one 0.98 g mp 123.5-124.5° [a] 134° (CHCI3). 

Interestingly, the product actually isolated from alkyne hydration is not the vinylic alcohol, or enol (ene + ol), but is instead a ketone. Although the enol is an intermediate in the reaction, it immediately rearranges to a ketone by a process called keto-enol tautomerisni. The individual keto and enol forms are said to be tautomers, a word used to describe constitutional isomers that interconvert rapidly. With few exceptions, the keto-enol tautomeric equilibrium lies on the side of the ketone enols are almost never isolated. We ll look more closely... 

In contrast, the acid-catalyzed hydration of arylbenzoylacetylenes differs markedly from the hydration of a-unsaturated ketones. Hydration of unsaturated ketones has been shown to proceed via a 1,4-addition mechanism where protonation occurs on oxygen to give an oxonium salt, followed by attack of water at the 0-carbon to give a hydroxy enol. The rate-limiting step has been shown to be the protonation of the hydroxy enol (27) ... 

Ketones from Aoetylenes Alkylation of carbonyl compounds (p T 108) with propargyi halides gives 7,5-acetyienic ketones. Hydration then gives a 1,4-diketone of a type we shall use in Chapter T 25 as in the following example, ... 

The use of mesitoic acid esters has again been successfully employed by Burrows and Topping (1975) in the elucidation of intramolecular carbon acid participation. Under basic aqueous conditions, 2-acetylphenyl mesitoate [41] hydrolyses to yield mesitoic acid and 2-hydroxyacetophenone, reacting with intramolecular catalysis via the monoanion of the ketonic hydrate (see p. 192). However, in 47.5% aqueous ethanol containing potassium hydroxide, the reaction products from l-acetyl-2-naphthyl mesitoate [45] were found... 

H20 or alcohols as nucleophiles give low molecular weight compounds when they add to the C=0 double bond of carbonyl compounds. These addition products are called aldehyde or ketone hydrates (Section 9.1.1) and hemiacetals or hemiketals (Section 9.1.2), respectively, depending on whether they result from the addition to an aldehyde or a ketone. Today, one no longer distinguishes systematically between hemiacetals and hemiketals, but the expression hemiacetal is frequently used to cover both. 

The reaction was rationalized by a ruthenium enolate mechanism (Fig. 4). Water served as a nucleophile and added to alkynes then the intermediate isomerized to give a ruthenium enolate, which then underwent addition to a-vinyl ketone followed by protonation to afford the 1,5-diketone. During the reaction, no ketone resulting from the hydration of the alkynes was found, which showed that the conjugate addition is faster than protonation of the ruthenium enolate in this aqueous reaction. 

Loss of water from the hydrate of the ester occurs by the same mechanism as loss of water from the hydrate of a ketone (Section 18-13). Protonation of either of the hydroxyl groups allows it to leave as water, forming a resonance-stabilized cation. Loss of a proton from the second hydroxyl group gives the ester. 

This method finds commercial application in the production of acetaldehyde from acetylene. Mercuric salts in the presence of dilute sulfuric acid act as the catalyst. The reaction has been extended to higher alkylacetylenes, which are obtained in about 60% yield from sodium acetylide and alkyl halides. These compounds are readily hydrated in aqueous solutions of acetone, methanol, or acetic acid to give 80-90% yields of the corresponding methyl ketones, fot example, methyl butyl, methyl amyl, and methyl hexyl ketones. Hydration has been accomplished by passing the acetylenic hydrocarbon and steam over a phosphoric acid catalyst at 150-204° and atmospheric pressure. ... 

The pathway from the equilibrium mixture XV-XVI to the target compound II may well split again to follow a ketonic-type cleavage either via nitrile ketone hydrate (XX - XXI), or by a shorter route that requires the intervention of XXVII (see Scheme 16.4). 

The carbanions derived from acylthiophenes have been condensed with aldehydes, -" and, through the Claisen condensation with esters, thienylsubstituted j8-diketones have been obtained. 2-Thenoyl trifluoroacetone, first prepared by Reid and Calvin through the Claisen condensation of 2-acetylthiophene with ethyl trifluoracetate, has become an extremely useful chelating agent for the extraction of numerous elements from strongly acidic solutions. The tautomeric form which dominates in aqueous solution is the ketone hydrate. Other thiophenes have also proved useful for analytical purposes. - ... 

In acidic media, polarized multiple bonds often undergo acid catalyzed addition, and a common mode of addition is the Ad 2. Deprotonation of the nucleophile by solvent gives the neutral compound. Common examples of this easily reversible Adg2 reaction are the formation of hydrates (NuH is H2O) and, if NuH is ROH, hemiacetals (from aldehydes) and hemiketals (from ketones). Usually this reaction favors reactants. 

Bromosinomeneine ketone [lxxvi]. can be made to undergo the benzil —> benzilic acid transformation in hot alkali, the product being 1-bromosinomenilic acid [xcm]. This acid is also obtained when the amorphous product of bromination of 1-bromosinomeninone with one equivalent of bromine is treated with alkali, and from sinomenine hydrate and one equivalent of bromine [69]. 

Dt hydrochloride pentahydrate, C14HMC12N2Ot5H20, Spectam, Spectogard, Staailo, Togamycin, Trobicin. Exists as a ketone hydrate and not in the carbonyl form. Cochran et al, foe. cit. Colorless needles from aqueous acetone, mp 205-207° (dec). [ ]D +14.8° (c = 0.42 in water). Soly in water, methanol, propylene glycol, 0.1 N NaOH. 0.IN HCl > 20 mg/ml, Marsh. Weiss, J. Assoc. Of/ic. Anal. Chem. 50, 457 (1967). Very slightly sol in benzene, chloroform, ethanol, acetone. 

---