Esterification of formic acid

A-7. Draw the structure of the tetrahedral intermediate in the esterification of formic acid with 1-butanol. 

Saha B. and M. M. Sharma, Esterification of formic acid, acrylic acid and methacrylic acid with cyclohexene in batch and distillation column reactors Ion-exchange resins as catalysts. React. Fund Polym. 28, 263-278 (1996). 

Formic acid forms esters with primary, secondary, and tertiary alcohols. The high acidity of formic acid makes use of the usual mineral acid catalysts unnecessary in simple esterifications (17). Formic acid reacts with most amines to form formylamino compounds. With certain diamines imida2ole formation occurs, a reaction that has synthetic utiHty (18) ... 

The methyl ester has also been obtained by esterification of cyclopentanecarboxylic acid.8 The acid, in turn, has been prepared by the Favorskii rearrangement,6 7 9-11 by the reaction of cyclopentyl Grignard reagent with carbon dioxide,12 by the carbonylation of cyclopentyl alcohol with nickel carbonyl13 or with formic acid in the presence of sulfuric acid,14 and by the hydrogenation of cyclopentene-1-carboxylic acid prepared from ethyl cyclopentanone-2-carboxylate 15 or from cyclopentanone cyanohydrin.16... 

Carbonyl)chlorohydridotris(triphenylphosphine)ruthenium(II) was used as a catalyst in the transfer hydrogenation of benzaldehyde with formic acid as a hydrogen source. Under these conditions, the reduction ofbenzaldehyde to benzyl alcohol is accompanied by esterification of the alcohol with the excess of formic acid to provide benzyl formate (Scheme 4.16). In this microwave-assisted reaction, the catalyst displayed improved turnover rates compared to the thermal reaction (280 vs. 6700 turnovers/h), thus leading to shorter reaction times36. 

Esters of formic acid (Expt 5.143) are most simply prepared from the alcohol and an excess of formic acid, which, being a comparatively strong acid, does not require the use of added mineral acid to catalyse the esterification reaction. Sulphuric acid in any case should not be added since it causes the decomposition of formic acid to carbon monoxide. 

Dimethylformamide was suggested for the GC detection of microgram amounts of formic acid [182]. After esterification of acids with diazomethane the sample was treated with a dimethylamine—water mixture (1 2). Dimethylformamide was thus produced from formic acid ester, while other acids present were analysed as methyl esters. 

This product comes from the esterification reaction of formic acid with methanol according to the following reaction ... 

Esterifications of benzoic acids with ethanol, N HCl ref. 14, p. 189. Reaction of benzoic acids with cyclohexanol, acid catalyst ref. 16. Reaction of benzoyl chlorides with ethanol ref. 14, p. 189. Reaction of anilines with formic acid ref. 14, p. 190. 

A catalytic cycle based on these observations is shown in Scheme I. The decomposition of the starting material HW2(CO)10 to HW(C0)5 and its subsequent reaction with C02 to yield HC02W(C0)5 have been reported elsewhere (5,6). The presence of formic acid, which subsequently undergoes esterification to afford methyl formate, was detected by GC when the reaction was carried out in benzene. 

In contrast to other esterifications, a significant extent of reaction can be reached even without a catalyst though the reaction equilibrium constant is approximately one. A compilation of the major physical property data can be found elsewhere [25, 87]. Fig. 10.2 shows the residue curve map in transformed coordinates as introduced by Doherty and coworkers [108] at a pressure of 1.013 bar. Due to a single maximum azeotrope, there are two distillation regions. The concentration profile in a single feed, two product lab-scale column with 45 bubble cap trays is also displayed in Fig. 10.2. The column is fed with a stoichiometric feed of formic acid and methanol and operated at a reflux ratio of 5. Water and the desired methyl formate are recovered at purities of about 97 % molar concentration in the bottoms and at the top, respectively. 

Typic2il examples of acid-catalysis of heteropoly compounds are as follows Dehydration of methanol, - > ethanol, - - propanol - - - -"- "- > and butanol, conversion of metanol or dimethyl ether to hydrocarbons, etheration to form methyl /-butyl ether, esterifications of acetic acid by ethanol and pentanol, decomposition of carboxylic acid and formic acid, alkylation of benzene by ethylene and isomerization of butene, o-xylene and hexane. ... 

Anderianova studied the decomposition of formic acid and esterification of acetic acid with ethyl alcohol in the vapor phase over gel-type resins of divinylbenzene content of 1 % and 20%. At lower temperatures, the resin with lower degree of crosslinking was more active for both reactions. With increasing temperature, the difference in the rates decreased. This was attributed to the change in resin sorption capacity with temperature. On the other hand, it was reported that, for the liquid-phase dehydration of t-butyl alcohol with gel-type resins, the 8%-crosslinked resin had about twice the catalytic activity of the 2% resin. 

The rate of ester formation depends on the carboxylic acid and the alcohol used. The lowest members, i.e. methanol and formic acid, react most readily. Primary alcohols react faster than secondary alcohols and the latter react faster than tertiary ones. Within each series, the reaction rate generally decreases with increasing molecular mass. Straight-chain acids react more readily than branched ones particularly branching in the a-position lowers the rate of esterification. Esterification of aromatic acids, e.g. benzoic... 

By trans-esterification, the degree of acetylation can be easily controlled allowing polymers to form with a wide range of hydrophobicity. Starch acetate can be prepared by the acetylation of starch with pyridine acetic anhydride mixtures and cast into films from 90% solutions of formic acid. The wet strength of the film is maintained in the aqueous solution with sufficient acetyl content when exposed to buffered amylase solution. But the acetyl content permits degradation by a mixture of a- and /5-amylase in 1 h. These films can be useful as membranes for bioreactors, which are degraded by enzyme addition. 

Formic acid exhibits many of the typical chemical properties of the aHphatic carboxyHc acids, eg, esterification and amidation, but, as is common for the first member of an homologous series, there are distinctive differences in properties between formic acid and its higher homologues. The smaller inductive effect of hydrogen in comparison to an alkyl group leads, for example, to formic acid = 3.74) being a considerably stronger acid than acetic acid... 

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