Intermolecular reactions formic acid

The intermolecular reaction of phenols with propiolic esters occurs in the presence of a Pd(OAc)2 catalyst to afford coumarin derivatives directly.48,48a An exclusive formation of 5,6,7-trimethoxy-4-phenylcoumarin is observed in the Pd(OAc)2-catalyzed reaction of 3,4,5-trimethoxyphenol with ethyl phenylpropiolate in TFA (Equation (46)). Coumarin derivatives are obtained in high yields in the cases of electron-rich phenols, such as 3,4-methylenedioxyphenol, 3-methoxyphenol, 2-naphthol, and 3,5-dimethylphenol. A similar direct route to coumarin derivatives is accomplished by the reaction of phenols with propiolic acids (Equation (47)).49 A similar reaction proceeds in formic acid at room temperature for the synthesis of coumarins.50,50a Interestingly, Pd(0), rather than Pd(n), is involved in this reaction. 

Data in 50% dioxan-water (Fife and Anderson, 1971). The reference intermolecular reaction is the hydrolysis of 2-phenoxytetrahydropyran at 50° catalysed by formic acid (pK, 4.64 under these conditions). The EM given by the authors (580 M) is a lower limit because no corrections were made for T or pK,. Applying both corrections (ct= 0.5, AHt = 10-15 kcal mol-1) gives EM 4-9 x 103... 

Fife and Anderson, 1971. The reference intermolecular reaction is the hydrolysis of the methyl ester catalysed by formic acid (p/f, of the substrate assumed the same as for H1.7)... 

The ratio of rate constants for intramolecular general acid catalysis of the hydrolysis of [73] and intermolecular formic acid-catalysed hydrolysis of 2-phenoxytetrahydropyran is 580 M, a minimum value since the intramolecular reaction was studied at 15° while the bimolecuUir rates were measured at 50°. The ratio would be much larger if comparisons could be made at the same temperature... 

Later, they also reported an intermolecular hydroacylations of 1,3-dienes with aromatic aldehydes yielding the corresponding j8,y-unsaturated ketones (Eq. 51) [79]. This reaction does not require a CO atmosphere. The addition of formyl C-H bond in formic acid esters and amides to olefins and conjugate... 

Selectivity on metal oxide catalysts is ultimately determined by complex intermolecular and surface-adsorbate interactions. Competing reaction channels are facilitated or hindered by the coordination geometry around metal cations, the ease of reduction of the surface, and the resulting stabilization of surface intermediates. The decomposition of relatively simple organic molecules like methanol and formic acid can be surprisingly complex, but attention to a few concepts may help to understand the reaction processes ... 

Intermolecular reactions of species (69) with simple alkenes have received little attention. Recently, a study of the reaction of 5-ethoxy-2-pyrrolidinone with several 1,3-dienes in the presence of acid was published. When a mixture of ethoxylactam and 2,3-dimethylbutadiene is stirred in neat formic acid, the formates (73) and (74) are isolated as the main products in 43% yield. The bicyclic product (75) is obtained in only 16% (equation 38). If the reaction is carried out in benzene with p-toluenesulfonic acid as catalyst (75) is formed in 19% yield. Other dienes show similar behavior, producing bicyclic compounds as byproducts in low to moderate yields except for one or two cases, as illustrated with com-... 

The first step, ring opening, is a characteristic reaction of furan derivatives. The final step is an intermolecular oxidation-reduction reaction. Evidence for this mechanism (71) is given by the isolation under similar conditions of the acetal derivative of the intermediate five-carbon keto aldehyde, and by the high yield of levulinic acid produced from it by the action of acids. Yields as high as 80 % of levulinic acid have been obtained from 5-hy-droxymethylfurfural. Furthermore, radioactive formic acid is derived by this reaction from D-glucose-l-C whereas the accompanying levulinic acid is devoid of activity (7 ). 

Colominas et al. [143] published a very detailed study on the dimerization of formic and acetic acids in the gas phase and in aqueous and chloroform solutions. By using quantum mechanical self-consistent reaction field and Monte Carlo calculations, they showed that the dimerization is favored in the gas phase and in a chloroform solution (1M) basically due to double hydrogen-bonded interaction between the monomers. In aqueous solution, the dimerization does not seem to occur due to the competitive solute-solvent intermolecular interactions. The computed dimerization energies are shown in Table VII. 15... 

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