Isopropyl alcohol, dissociation

In this Section, we consider examples of application of semiconductor sensors in investigation of heterogeneous catalytic reactions of dehydration of isopropyl alcohol and dissociation of hydrosine on zinc oxide. 

Figure 4.8. displays oscillograms of evolution of the electric conductivity of the ZnO film in the process of catalytic dehydration of isopropyl alcohol at various temperatures of the catalyzer and equal portions of alcohol (5-10-2 Torr) admitted into the reaction cell. Experimental curves 1-4 are bell-shaped. We suppose that this fact is associated with two circumstances. On one hand, alcohol vapors dissociate on the oxide film producing hydrogen atoms. The jump in electric conductivity is caused by chemisorption of these hydrogen atoms on the film which plays a part of the sensor in this case. Chi the other hand, the drop in electric conductivity is caused by complete dissociation of the admitted portion of alcohol ( depletion of the source of hydrogen atoms) and by... 

The fundamental method of calculating AG is from equilibrium measurements, primarily from measurement of the equilibrium constant of a chemical reaction. As an example, we shall consider the dissociation of isopropyl alcohol to form acetone and hydrogen ... 

If we start with o moles of isopropyl alcohol, a no mole each of acetone and hydrogen are formed, where a is the degree of dissociation. The quantity of... 

Use the bond dissociation energies in Table 7.1 to calculate an approximate AH° (in kilojoules) for the industrial synthesis of isopropyl alcohol (rubbing alcohol) by reaction of water with propene, as shown at the top of the next column. 

The relation between the excitation state of the surface bonds and the activation energy, discussed so far, is easy to understand when the rate-determining step of the reaction considered involves the dissociation of the more or less excited surface bond. In order to investigate the importance of the excitation state of the surface bond in a reaction without oxygen transition, the decomposition of isopropyl alcohol vapour on a ZnO catalyst in the dark and in ultraviolet light has been studied 93-95). 

Isopropyl alcohol can dissociate into acetone and hydrogen ... 

It therefore seems likely that C3H7OH2+ will be the major positive ion remaining in pure isopropyl alcohol after ion-molecule reactions, though it will be of the clustered form C3H7OH2+(C3H7OH)y, and that neutralization will proceed via Reaction 6. The mercury photosensitized decomposition of isopropyl alcohol shows a high quantum yield of H atoms (21) and a yield of H atoms from dissociation of excited isopropyl alcohol molecules might also be expected in the radiolysis. Hence, as for water vapor, the yield of H atoms from pure isopropyl alcohol will have... 

Rafols C, Roses M and Bosch E, Dissociation constants of several nonsteroidal anti-inflammatory drugs in isopropyl alcohol /water mixtures. Anal. Chim. Acta, 350,249-255 (1997). NB Potentiometric method using i-PrOH/water mixtures in the range 10/90 to 90/10 v/v. Metrohm autotitrator careful electrode calibration. Activity corrections applied and extrapolated to zero [i-PrOH]. Alternative data handling procedure gave pKa = 4.64 0.04. 

Indicator (dissociation Optimum Water Isopropyl alcohol t-Butyl alcohol Dimethylformamide ... 

Ionic equilibria in solvents of low relative permittivity have been described in the literature and equations for calculating titration curves have also been proposed. The equations involve the partial dissociation of the acids, bases, and salts in these media, and the effect of the activity coefficients. The equations can be applied to pH and titration curve computation in solvents such as t-butyl and isopropyl alcohols, ethylene diamine, pyridine, or tetrahydrofuran. 

As mentioned (Table 4.24), the k values are essentially the same for all three alcohols and agree well with rate constants for the dissociation of (9-BBN)2 in noncomplexing solvents such as hexane, CCl, and cyclohexane. As expected, k decreases in the order methanol > ethanol > isopropyl alcohol (Table 4.24) [1]. 

The series of indicators studied in the use of nonaqueous solvents for the titrations of acids, isopropyl and -butyl alcohols, and dimethylformamide exhibit three more models of acid dissociation shown in the following reactions and equations ... 

The primary degradation reaction was dissociation of allophanate into phenyl isocyanate and alkyl carbanUate, followed by dissociation of the alkyl carbanUate into phenyl isocyanate and alcohol. Decarboxylation of the ethyl carbanUate fragment also took place slowly. A small amount of diphenyl carbodimide was observed at the pyrolysis temperature of 450°C. In addition, decarboxylation of the isopropyl carbanUate fragment took place at 550°C. A small amount of diphenyl carbodimide was observed from 350°C to 550°C. 

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