Equilibrium constants and rates of dehydration of formaldehyde in buffered solutions of light and heavy water studied at DME

Cluşaru, A.; Crişan, I.; Kůta, J.

doi:10.1016/s0022-0728(73)80177-9

Cited by 13 publications

(11 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This decrease in pK a values is consistent with the known trend of the in¯uence of ionic strength on the reaction rate constant, i.e. the ionic strength does not in¯uence the rate constant of reaction between non-charged species [direct reaction (2)] and increases the rate of reaction involving two species with opposite charge [reverse reaction (2)]. 21,22 When comparing numerical pK a values at the ionic strengths 0.4 and 1.0 mol dm À3 respectively it is seen that the smallest dierence is observed in the case of LiOD± LiNO 3 as supporting electrolyte and the dierence rises in the sequence of alkali-metal ions Li <Na <K .…”

Section: Resultssupporting

confidence: 86%

See 1 more Smart Citation

Influence of Ionic Strength and Cation Nature on the Deprotonation of Methanediol in Alkaline Solution†

Norkus¹,

Pauliukaitė²,

Vaškelis³

et al. 1998

J. Chem. Res.

View full text Add to dashboard Cite

show abstract

Section: Resultssupporting

confidence: 86%

“…The equilibrium constant of reaction (1) was found to be 2 Â 10 3 1 and 2.3 Â 10 3 . 2,3 This suggests that nearly all formaldehyde is present in hydrated form in aqueous solutions. In alkaline aqueous solutions dissociation (deprotonation) of methanediol occurs: 4 H 2 COH 2…”

mentioning

confidence: 99%

Influence of Ionic Strength and Cation Nature on the Deprotonation of Methanediol in Alkaline Solution†

Norkus¹,

Pauliukaitė²,

Vaškelis³

et al. 1998

J. Chem. Res.

View full text Add to dashboard Cite

show abstract

“…The equilibrium constant of Reaction 1 was found to be 2610 3 [1] and 2.3610 3 [2,3]. This suggests that nearly all the formaldehyde is present in hydrated form in aqueous solutions.…”

Section: Formaldehyde Is Hydrated In Aqueous Solutions Forming Methanmentioning

confidence: 91%

“…Only free unhydrated formaldehyde (CH 2 O) is reduced on DME, the process was studied in both buffered [8,10] and nonbuffered [2,3,11] solutions. The height on the polarographic wave was found to be lower than the diffusion limiting current corresponding to analytical formaldehyde concentration, and the polarographic wave to be kinetic one.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Polarographic Determination of Formaldehyde According to the Anodic Oxidation Wave in Alkaline Solutions

1999

View full text Add to dashboard Cite

The polarographic waves of CH 2 O oxidation in 2±3 M NaOH solutions containing 0.04±0.10 M ()-tartrate are diffusion controlled: the dependences of limiting current (i lim ) on the square root of the Hg column height are linear and the temperature coef®cient of the limiting current is relative small, i.e., $ 2 % grad À1 . The anodic waves of CH 2 O oxidation could be used for analytical purposes. [2,8]. The scatter in the available pK a values of the methanediol deprotonation can be attributed to different ionic strength of the solutions investigated and nature of the supporting electrolyte [9].Thus, formaldehyde exists mainly in the form of methanediol and its anion in the solutions under investigation.The reduction of formaldehyde on dropping mercury electrode (DME) is well known. Only free unhydrated formaldehyde (CH 2 O) is reduced on DME, the process was studied in both buffered [8,10] and nonbuffered [2,3,11] solutions. The height on the polarographic wave was found to be lower than the diffusion limiting current corresponding to analytical formaldehyde concentration, and the polarographic wave to be kinetic one. The height of polarographic wave increases with increase in pH of the solution, passes through a maximum at pH $ 13.15, and then decreases.The anodic oxidation of formaldehyde on a DME was detected recently [12]. It was shown that the anodic current of CH 2 O oxidation on the DME is observed in alkaline solutions at relatively positive potentials close to the anodic dissolution of Hg. The polarographic waves of CH 2 O oxidation are diffusion controlled: the dependences of limiting current (i lim ) on the square root of the Hg column height are linear and the temperature coef®cient of the limiting current is relative small, i.e., $ 2 % grad À1 . The half wave potential's dependence on solution alkalinity suggests that two OH À anions participate in the oxidation reactionIt was shown in the same work that at pH $13 the anodic wave is a kinetic one in the presence of ()-tartrate. On the ground of polarographic and 13 C NMR investigations the kinetic nature of the anodic wave can be explained by a chemical reaction, i.e., formation of cyclic acetal-type compound [13].The aim of this work was to check the possibility to use the anodic oxidation wave on DME for the determination of formaldehyde concentration.The polarographic waves of formaldehyde anodic oxidation in NaOH supporting electrolyte are observed close to the potentials of the mercury anodic dissolution (Fig. 1a). The linear dependence of the limiting current on total concentration of hydrated formaldehyde, i.e., sum of methanediol and its anion concentration is observed in the range from 10 À4 to 10 À2 M. However, some dif®culties appear in the determination of the limiting current values in this case, the limiting current region of the polarograms being not distinctly expressed.The investigations carried out showed that this drawback can be eliminated by addition of 0.04±0.10 M ()-tartrate into the supporting electrolyte containing ...

show abstract

Polarography

Kůta

1984

Comprehensive Treatise of Electrochemistry

View full text Add to dashboard Cite

Equilibrium constants and rates of dehydration of formaldehyde in buffered solutions of light and heavy water studied at DME

Cited by 13 publications

References 24 publications

Influence of Ionic Strength and Cation Nature on the Deprotonation of Methanediol in Alkaline Solution†

Influence of Ionic Strength and Cation Nature on the Deprotonation of Methanediol in Alkaline Solution†

Polarographic Determination of Formaldehyde According to the Anodic Oxidation Wave in Alkaline Solutions

Polarography

Contact Info

Product

Resources

About