2-Propanone carbon acidity

Propanone (acetone) carbon acidity, 10 protection of diols as "acetonides , 158, 266-267, 276-277, 321, 322 reaction with pyrrole, 250-251 Propanoyl chloride, 2- acetyloxy)-2-methyI-(Moffatt s reagent) O-protection, 160 chlorohydrtns from diols, 160, 327-328 2-Propenal (acrolein, acrylaldehyde) pr., 174... 

Exercise 15-28 In the conversion of 2-propanol to 2-propanone with chromic acid, which is the redox step, esterification or elimination What is the change in oxidation level of carbon in this reaction ... 

Exercise 17-23 Aldol additions also occur in the presence of acidic catalysts. For example, 2-propanone with dry hydrogen chloride slowly yields (CH3)2C=CHCOCH3 (mesityl oxide) and (CH3)2C=CHCOCH=C(CH3)2 (phorone). Write mechanisms for the formation of these products, giving particular attention to the way in which the new carbon-carbon bonds are formed. 

The optical isomers of DOM have been prepared in two ways. The racemic base has been resolved as the ortho-nitrotartranilic acid salt by recrystallization from EtOH. The (+) acid provides the (+) or S isomer of DOM preferentially. Also, the above-mentioned l-(2,5-dimethoxy-4-methylphenyl)-2-propanone can be reductively aminated with optically active alpha-methyl benzylamine with Raney Nickel. This amine is isolated and purified by recrystallization of the hydrochloride salt. When optically pure, the benzyl group was removed by hydrogenolysis with palladium on carbon. The mp of either of the optical isomers, as the hydrochloride salts, was 204-205 °C. 

The rate of enolate-carbonyl equilibration " is dependent on the forward and backward rates of proton exchange. Proton exchange from a carbon-based acid is known to be slower than that of a more electronegative atom donor (in particular, O and N atoms) . For a series of closely related molecules usually the more acidic a given molecule is, the faster the rate of proton transfer (high kreu note that thermodynamic and kinetic parameters are not related). For example, benzocyclobutanone (10) is less acidic and the rate of deprotonation is substantially slower (10 times) than the related benzocyclopentanone (12) due to its enolate (11) having unfavourable anti-aromatic character. Deprotonation of the simplest cyclobutanone (13) clearly does not lead to an unfavourable anti-aromatic enolate (14) . By assuming the internal strain of 14 is similar to that of 11, cyclobutanone (13) is evidently 10 " times more acidic than benzocyclopentanone (12). By the same vain, the more acidic propanone (15) has a faster rate of deprotonation (10 times) than the less acidic ethyl acetate (16) . ... 

A The alkynyl hydrogen of propyne is acidic and hence the propyne will form an organometallic derivative. The Grignard derivative will react with carbon dioxide to give the carboxylic acid. Cis alkenes are formed by the catalytic hydrogenation of alkynes using a Lindlar catalyst. Hence a propynyl alcohol is a precursor to compound (b). This could be obtained by the addition of a propyne anion to propanone ... 

Garcia eta/, studied the reaction of the homochiral (iJ)-3- -tolylsulfinyl propanone 75 with Pd(OAc)2 in acetic acid at 70 °C under nitrogen for 48 h which yielded the enantiomerically pure trimer on. o-palladated compound 76 containing a stereogenic carbon directly joined to the Pd atom (Equation 11) <1996TA139>. 

By this synthesis, it will be noticed that the alpha- immo acids result as the amino group is always linked to the carbon to which the carboxyl is also linked. The amino acid will also contain one more carbon than the aldehyde or ketone due to the addition of the cyanide radical, i.e.y acetic aldehyde yields amino propionic acid and propanone (acetone) yields amino iso-butyric acid. 

In saccharides, cleavage by periodic acid or sodium periodate occurs between any carbons possessing/ree hydroxy lie groups. Thus glucosazone treated with periodic acid in aqueous ethanol at room temperature is degraded to the l,2-bis(phenylhydrazone) of mesoxalaldehyde (propanone-dial) in 85% yield [759]. 

Generally, an aldehyde would react faster, because it has only one electron donating group reducing the positive nature of the carbonyl carbon. Thus, taking this line of reasoning a step further, methanal reacts faster than ethanal. In fact, methanal hydrates quite rapidly even at pH 7, while propanone only hydrates very slowly at that pH, and requires either acid or base catalysis for this reaction to proceed at a significant rate. 

Phenylacetone, also known as methyl benzyl ketone, or l-phenyl2-propanone, is easy but tedious to make. In this reaction, phenylacetic acid reacts with acetic anhydride with pyridine catalysts to produce phenylacetone plus carbon dioxide and water. In chemical writing ... 

Only a few ketones have common names. The smallest ketone, propanone, is usually referred to by its common name, acetone. Acetone is a common laboratory solvent. Common names are also used for some phenyl-substituted ketones the number of carbons (other than those of the phenyl group) is indicated by the common name of the corresponding carboxylic acid, substituting ophenone for ic acid. ... 

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