Acetalization reaction

The carboxyl group of acids appears to deactivate the hydrogens on the alpha carbon atom toward attack by the free-radical flux in oxidation reactions. Acetic acid, therefore, is particularly inert toward further oxidation (hydrogens are both primary and deactivated) (48). For this reason, it is feasible to produce acetic acid by the oxidation of butane (in the Hquid phase), even under rather severe oxidation conditions under which most other products are further oxidized to a significant extent (22). 

TorteUi-JaffH reaction acetic acid + 2 wt% Br2 in CHCl green sterols with ditertiary double bonds vitamin D and compounds that give similar bonds upon isomerization or... 

In this reaction, acetic acid donates a proton to produce its conjugate, the acetate ion, which is able to function as a proton acceptor. Ammonia accepts a proton to produce its conjugate, the ammonium ion, which can function as a proton donor. Two species that differ by the transfer of a proton are known as a conjugate pair. The conjugate acid of H20 is H30+, and the conjugate base of H20 is OH-. 

The hydrolysis of acetic anhydride is being studied in a laboratory-scale continuously stirred tank reactor (CSTR). In this reaction acetic anhydride [(CH3C0)20] reacts with water to produce acetic acid (CH3COOH). 

For these more efficient reactions the rate of the intermolecular reaction (acetate-catalysed detritiation) is too slow relative to that of the intramolecular reaction to be measured accurately. These EM s are therefore based on estimated upper limits for the rates of the reference reactions Harper and Bender, 1965. The reference intermolecular reaction is the benzoate-catalysed enolization of PhCOCHMe2... 

The overall effective pathlength of a CIR cell is relatively short (ca. 10 pm) which has both advantages and disadvantages. The short pathlength means that spectra can be measured even on highly absorbing samples, such as aqueous solutions, or (as in the case of methanol carbonylation reactions) acetic acid-water mixtures. 

As in all large-scale industrial processes, the formation of the cellulose esters involves recovery of materials. Acetic anhydride is generally employed. After reaction, acetic acid and solvent are recovered. The recovered acetic acid is employed in the production of additional acetic anhydride. The recovered solvent is also reintroduced after treatment. 

During the reaction, acetate, or the growing fatty acyl chain is initially esteri-fied to the sulfhydryl group of a cysteine residue of the enzyme. 

Acetals are formed by reacting an aldehyde or a ketone with an alcohol (2 equivalents) in the presence of a catalytic amount of acid. Water is released and this ts trapped out to facilitate the forward reaction. Acetals are stable to base but decompose into their starting materials when treated with aqueous acid ... 

The reaction is carried out in the dark to avoid decomposition and side reactions. Acetic acid p.a. was obtained from Merck-Schuchardt, Hohenbrunn, Germany. 

Complex (88) with an iodide source was again used. The selectivity was surprisingly dependent on the cation of the iodide. It has been found that cobalt(II) acetate improves the conversion and selectivity achieved in equation (71) when used together with complex (88) as catalyst.383 In a related reaction, acetic acid was carbonylated to propionic acid (equation 72). 

Since alcohols and aldehydes are both formed in the Oxo reaction, acetals are formed (158). A recent paper by Macho (87) studied their further reactions under Oxo conditions, hydrolysis, hydrogenolysis, and thermal decomposition. Decomposition to saturated and unsaturated ethers increased with temperature from 12% at 120° to 41% at 170° C. Thus isobutyl ether, isobutenyl isobutyl ether, isobutanol, and isobutyraldehyde were identified by gas-phase chromatography among the reaction products of the decomposition of isobutyraldehyde diisobutyl acetal. 

Further Reduction to a Hydrocarbon. In the reduction of benzo-phenone with aluminum ethoxide the formation of 7% of diphenyl-methane was observed. When benzohydrol was treated with aluminum ethoxide under the same conditions, 28% reduction to diphenylmethane occurred.12 In these reactions acetic acid, rather than acetaldehyde,-was formed from the ethoxide. Aluminum isopropoxide does not give this type of undesirable reaction with this reagent, pure benzohydrol is easily obtained in 100% yield from benzophenone.6 37 However, one case of reduction of a ketone to the hydrocarbon has been observed with aluminum isopropoxide.17 When 9, 9-dimethylanthrone-10 (XU) was reduced in xylene solution, rather than in isopropyl alcohol, to avoid formation of the ether (see p. 190), the hydrocarbon XUII was formed in 65% yield. The reduction in either xylene or isopropyl alcohol was very slow, requiring two days for completion. 

In this reaction, acetals are used as dication equivalent of one-carbon unit 72, whereas 71 provides a dianion 73 <95TL5581>. A new stereocontrolled synthesis of substituted tetrahydrofiirans starts with dioxalones 74. A titanium-mediated methylenation using dimethyltitanocene (THF, 60 C) with subsequent treatment of 75 with trialkylaluminium reagents results in the formation of tetrahydrofiirans 76 <95JA6394>. 

O In the first step of the reaction, acetate anion leaves to generate the mercury electrophile. 

Addition of Heteroatom Nucleophiles to Carbonyl Compounds in Combination with Subsequent SN1 Reactions Acetalizations... 

Methylation of the hydroxyl group of CD in OMeCD does not affect all reactions in the same way. In the hydrogenation of ethyl pyruvate 9 the influence is only marginal, independent of the solvent used. A similar small effect was observed in the hydrogenation of 4 in apolar solvent, while the ee increased by 20 % in acetic acid, using OMeCD instead of CD. On the contrary, O-methylation of CD led to a remarkable drop in ee in the hydrogenation of 1 in apolar solvents such as 1,2-dichlorobenzene. In the latter reaction, acetic acid is a poor solvent, affording low ee s with both CD and OMeCD. 

Recently, a few examples of imino Diels-Alder reactions using azetinones as dienophiles have been described in work aimed at synthesis of carbapenems. In one sequence of reactions, acetate (34) was treated with a Lewis acid in the presence of a siloxy diene to afford adduct (36) (equation ll). This transformation presumably involves imine (35) which reacts both regio- and stereo-selectively with the diene. Adduct (36) was converted in a few steps to carbapenem (37). 

The commercial process for the production of aspirin (or acetylsalicylic acid) involves a one-pot acylation reaction. Acetic anhydride reacts with salicylic acid in the presence of a small amount of sulfuric acid to produce acetylsalicylic acid and acetic acid. 

Despite the lower rate in the presence of inhibitor, radioactively labelled palmitate was added to a CHCla-inhibited system. Table IV shows that butyrate was formed at a faster rate than formate, acetate, or propionate. The fact that butyrate was now one of the major end products of palmitate dissimilation indicates that secondary reactions involving acetate and/or propionate were probably serving to remove hydrogen produced during dissimilation since methanogenesis was inhibited in these experiments. This was partially verified by the findings that radioactively labelled acetate was converted to formate and butyrate at faster rates in inhibited than in uninhibited sludge. It is also possible that formation of butyrate indicates some alternative to -oxidation as a dissimilatory reaction. Acetate itself was formed from C02 in the presence or absence... 

Acetalation Reactions Acetal-Type Protecting Groups. 121... 

In the Perkin reaction, acetic anhydride condenses with an aromatic aldehyde to yield a cinnamic acid. The reaction takes place by a mixed carbonyl condensation of the anhydride with the aldehyde to yield an a,/l-unsaturated intermediate that undergoes hydrolysis to yield the cinnamic acid. What is the structure of the unsaturated intermediate ... 

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