Polarographic method, determination formaldehyde

Finally, some important studies of the influence of pH in the reaction between formaldehyde and amine in biological. systems, in the aminomethylation of polyacrylamide, and in the use of aldehydes other than foiTnaldchyde- - lead to the conclusion that under acidic conditions, aldehyde attack by the amine is the rate-determining step. Under neutral or basic conditions the rate-determining step is hydroxyl elimination from the methylolamine HO—CH2—NR2 with formation of the methyl-cncimmonium cation. - Polarographic methods demonstrate that the maximum concentration of this last species occurs at a pH near 10. 

A terminal 1,2-diol yields formaldehyde, whereas the carboxylic derivatives yield carbon dioxide. Several methods are available for detecting and determining these important products in reaction mixtures formaldehyde may be determined as a sparingly soluble methone, " by its highly spedlic color reaction with chromotropic acid, or polarographically conventional, manometric techniques are utilized for measurement of the carbon dioxide from carboxylic adds. 

Water, formaldehyde, acetaldehyde, acetone, methanol, hydrogen peroxide, CO, CO2, and H2 were detected among the volatile products. The aldehydes and hydrogen peroxide were determined by a polarograph-ic method. Gas and gas-liquid chromatography were used to analyze the other products. Coal and fine white sand with dipropionitrile ester as the stationary phase were used as the adsorbants. The gas carrier was helium. 

Even though several methods have been devised for the oxidation of methanol and ethanol to formaldehyde and acetaldehyde, with the subsequent polarographic determination of these aldehydes, none of them has yet been widely accepted. The nonreproducibility of the oxidation, volatility of both alcohols and aldehydes formed, the reactivity and polymerization of the aldehydes and the kinetic character of the wave of formaldehyde, seem to be the main reasons for this situation. 

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