Observations on a possible mechanism of the cannizzaro reaction with formaldehyde

Abstract

The interaction between aldehydes and alkaiies effecting simultaneously the oxidation and the reduction of the aldehyde to an acid and an alcohol, respectively, is termed the Cannizzaro reaction ,).This reaction is commonly represented by the following equation wherein R is an alkyl or aryl radical and MOH a fairly strong base, usually sodium or potassium hydroxyde :Loew 3, omitting description of method and record of quantitative data, recorded the highly significant observation that the interaction of aqueous solutions of formaldehyde and sodium hydroxide yielded a very small amount of hydrogen, and that if cuprous oxide were added to the reaction mixture, it was reduced to metallic copper, which apparently catalyzed a reaction liberating pure hydrogen. This reaction may be represented by the following equation (a):Oxides of other metals noted by Loew did not give this result, but later Vanino 4, using silver nitrate, which was reduced to silver, also obtained hydrogen but to a lesser extent.Birstein and Lobanow 5, studying the kinetics of the formation of formic acid according to the Cannizzaro reaction, gave data showing that the reaction is probably trimolecular, but observed that two consecutive reactions may take place. The first is according to the above equation (a) wherein one molecule of formaldehyde is oxidized to sodium formate with the formation of a molecule of hydrogen, which, in turn, in the second reaction, reduces a second molecule of formaldehyde to methyl alcohol according to the following equation (b) : l) A synopsis of a section of the Doctorate Thesis of J. Waide Price, based upon a preliminary investigation by Jay J. Uber, continued and extended by J. Waide Price. 9 ) Cannizzaro, Ann. 88, 129 (1853); 90. 252 (1854). s, b e w , Ber. 20, 144 (1887). ' ) Vanino. Ber. 36. 3304 (1903). + n H O M -R(OM), + nH,. ") Fry, Schulze and Weitkamp. J. Am. Chem. SOC. 46, 2268 (1924): Fry and Schulze. ibid. 48, 959 (1926): Fry and Otto, ibid. 50, 1120 (1928): Fry andschulzr. ibid. 50, 1131 (1928): Fry and Otto. ibid. 50. 1138 (1928). ') Fry and Cameron, J. Am. Cbem. SOC. 49, 864 (1927): Fry and Bowman, ibid. 52. 1531 (1930). ") A. H.

Selective Oxidation of Methane to Methanol over ZSM‐5 Catalysts in Aqueous Hydrogen Peroxide: Role of Formaldehyde

“…An important difference is the gaseous hydrogen product reported for the first time in the present work . We note on this point, that the evolution of hydrogen from oxidation of formaldehyde by H 2 O 2 is well‐known …”

“…The present results also indicate that formldehyde is formed as an early product and it is then rapidly oxidised or undergoes conversion to POM. The direct oxidation of HCHO to give HCO 2 H by H 2 O 2 is known to occur at H 2 O 2 concentrations similar that used here . The amount of POM found is quite small and it would appear to increase slightly with reaction time, but these low levels make it difficult to establish the trend unambiguously.…”

“…Fry and Payne reported that the production of hydrogen [Eq. (3)] was favoured at lower concentrations of H 2 O 2 typical of the “standard” oxidation conditions used here . In our methane oxidation experiments, the progressive decrease in the concentration of H 2 O 2 caused by its consumption in the oxidation of methane and its decomposition over ZSM‐5(50) probably contributes to the promotion of H 2 production from formaldehyde.…”

“…The uncatalysed reaction chemistry of HCHO in acidified aqueous solutions of H 2 O 2 was investigated by Fry and Payne in the 1930’s . They also reported on the oxidation of methanol and formic acid by H 2 O 2 .…”

On the Mechanism of Formation and the Synthesis of Pantoprazole Sodium Sesquihydrate-Related Compound E: A Phantom Chemical Entity

“…Perhaps more importantly, commercial methanol may contain trace quantities of formaldehyde, 14 which is subsequently converted to formic acid in the presence of sodium hydroxide. 15 In fact, the formation of trace amounts of methylated drug substances during routine analytical experiments has been attributed to the presence of trace amounts of formaldehyde in HPLC-grade methanol. Finally, it should be noted that the N-2 and N-7 methylation byproduct is limited to pantoprazole and omeprazole, both of which contain an electron-donating group on C-5 of the benzimidazole moiety (Table 1).…”