Diacetone alcohol decomposition

Diacetone Alcohol Decomposition.- Tanabe et al. have used... 

Base-catalyzed reactions were reviewed in general by Hattori [208,222], and from the reactions described butene isomerization, alcohol conversion, toluene alkylation, acetone condensation/diacetone alcohol decomposition, Knoevenagel condensations, diketone cyclization, ring transformation reactions, and dimerization of aldehydes to the corresponding esters were used to evaluate the acid-base properties in molecular sieves. 

Diacetone alcohol decomposition to acetone (reverse reaction of acetone aldol condensation) proceeds over alkidine earth catalysts. The active sites are poisoned by COz- The slope of the activity decrease with increasing amount of adsorbed CO2 represents the activity per unit base site. The activities per unit site are in order BaO>SrO>CaO>MgO. The order coincides with the base strength order the stronger the base strength the more effective the active sites. 

In the form of single component oxides, one important feature is their basic property. Basic property was measured by benzoic acid titration. Basicity variation of La203 at H =12.2 as a function of calcination temperature was measured. The maximum basicity upon unit weight basis was observed with pretreatment at 773 K. The measured basicity correlates well with the catalytic activity for diacetone alcohol decomposition. ... 

Others The binary oxide Z1O2 —SnOz has both acid and base sites. The maximum strength of the acid sites is observed to be Ha= —3.0 at the composition ZrOz 90%. The acid sites on oxides of other compositions are weaker than ifo=1.5. The number of base sites on the binary oxide is less than on the component oxide ZrOz- The catalytic activities for cyclopropane ring opening and 2-butanol dehydration correlate with the acidity, while those for 1-butene isomerization and diacetone alcohol decomposition correlate with basicity. 

Diacetone alcohol decomposition Alkali and alkaline earth phosphates < )... 

By way of example, consider the first-order decomposition of 4-hydroxy-4-methyl-2-pentanone ( diacetone alcohol ) in a reaction that is catalyzed by hydroxide ions, carried out at constant [OH-] 6... 

Kinetic data for the decomposition of diacetone alcohol, from Table 2-3. were obtained by dilatometry. The nonlinear least-squares fit of the data to Eq. (2-30) is shown on the left. Plots are also shown for two methods presented in Section 2.8 they are the Guggenheim method, center, and the Kezdy-Swinbourne approach, right. 

The methods can be applied to the data presented earlier for the first-order decomposition of diacetone alcohol, Table 2-3. Figure 2-4 also presents the analysis... 

Wilkinson s method for the estimation of the reaction order is illustrated for first-order (left) and second-order (right) kinetic data. The first-order reaction is the decomposition of diacetone alcohol (Table 2-3 and Fig. 2-4) data to about 50 percent reaction are displayed. The slope gives an approximate order of 1.2. The second-order data (Fig. 2-2) give a precise fit to Eq. (2-59) and an order of two exactly. 

There are certain reactions, e.g. inversions of sucrose and methane etc. in which the rate of reactions were found to be proportional to the concentration of H+ ions. Similarly, there are reactions which are catalyzed by OH ions, e.g. conversion of acetone into diacetone alcohol or decomposition of nitroso-triacetoneamine. These are known as specific hydrogen ion catalyzed or specific hydroxyl-ion catalyzed reactions. Also there are some reactions in which both H+ and OFF ions act as catalysts probably along with water. The undissociated acid or base have negligible effect on the rate of reaction. The hydrolysis of ester is an example in which both H+ and OH ions act as catalyst... 

This agrees with A. E. Leighton s statement that when sodium carbonate is present in water used in steam boilers, the boiled water contains sodium hydroxide. J. Shields and K. Kolichen have measured the degree of hydrolysis of aq. soln. of sodium carbonate the former from measurements on the rate of hydrolysis of ethyl acetate, the latter from the decomposition of diacetone-alcohol, CH3.CO.CH2.C(CH3)2OH 2CH3.CO.CH3. The percentage hydrolysis of soln. of sodium carbonate of different cone, by the two methods are of the same order of magnitude ... 

The first-order rate constant for the base-catalysed decomposition of diacetone alcohol increases rapidly when Pr4N+OH" is added, less rapidly when Me4N+OH is added, and decreases on addition of KOH. The conclusion that the variation in rate constant stems from the effects of the added cation is confirmed by observing that, at a fixed concentration of KOH, added Et4N+I- increases and added KI decreases the rate constant (Halberstadt and Prue, 1952). More recently, Hibbert and Long (1972) observed that the rate constant for the water-catalysed detritiation of t-butylmalononitrile at 298 K... 

HMB is used as a nutritional supplement for human beings and also as an animal feed additive, and acts by suppressing protein breakdown. It is manufactured by Metabolic Technologies Inc. (Ames, Iowa). The reactions comprising the synthesis of HMB are the main reaction involving the decomposition of diacetone alcohol, known as the halofoim reaction, accompanied by several side reactions. 

The reverse reaction, i.e., the decomposition of diacetone alcohol to acetone, was used by Jurczyk and Kania [233]. They explored Fe-, Cr-, Ni-, Mo-, and Mg-modified aluminas as catalysts. Similarly, Na-X, Na-Y, H,Na-X, and H,Na-Y were employed by Przystaiko et al. [234] as a test reaction for sites with basic character. As the critical ability of the catalyst is to polarize bonds, acidic and basic sites play a role in the catalysis. However, the strength of the basic site will determine the effectiveness of the catalyst. 

Diacetone alcohol (keto-alcohol) DAA. Boil- Solvents with a high rate of evaporation have a ing point 166°C with decomposition to acetone, tendency to form a dry mist during spray application. With brush application the evaporation must be slow. 

The other reactions which can be used to estimate the basic property of a solid are the decomposition of 4-hydroxyl — 4-methyl — 2-pentanone (diacetone alcohol) and the isomerizaiton of 1-butene.In the latter reaction, use of isotope tracer gives information regarding the activity of basic sites. 

The reaction of 2-butanol over tin (IV) oxide at 573 K gives only methyl ethyl ketone, a dehydrogenation product butenes, dehydration products, are not formed. Tin oxides have catalytic activities for the decomposition of diacetone alcohol at 303 K S3) jjjgjg indicate that tin (IV) oxide is a basic rather than an acidic oxide. 

The variations of the activity for decomposition of diacetone alcohol, dehydration of 4-methyl-2-pentanol, and alkylation of phenol are shown as a function of the composition of the binary oxide in Fig. 3.52. The catalytic activity for decomposition of diacetone alcohol correlates with the number of base sites, while that for the dehydration of 4-methyl-2-pentanol correlates with the number of acid sites. The alkylation of phenol with methanol is most effectively catalyzed by a binary oxide possessing both acid and base sites, the oxide containing Ti02 and MgO in a 1 1 ratio being the most active. 

Bell, R.P. and Prue, J.E. (1949) Reaction-kinetic investigations of the incomplete dissociation of salts. Part I. The decomposition of diacetone alcohol in solutions of metallic hydroxides. J. Chem. Soc., 362-369. 

The effect of methyl deuteration on the cleavage of diacetone alcohol has also been determined by Pocker (141), who notes that base-catalyzed cleavage does not involve enolization, but simple decomposition of the alkoxide ion ... 

---