Sucrose catalyzed hydrolysis

Monomethylacryloyl and vinylbenzyl derivatives of sucrose have been prepared as intermediates for polymers, and preparation of a range of copolymers of styrene and O-methjiacryloylsucrose has been described (114). Synthesis of 4- and 6-0-acryloylsucrose has been achieved by acid-catalyzed hydrolysis of 4,6-0-(l-ethoxy-2-propenyhdene)sucrose (76). These acryloyl derivatives have been polymerized and copolymerized with styrene (qv). 

For the most part, low molecular weight carbohydrates of commerce are made by depolymerization via enzyme- or acid catalyzed hydrolysis of polysaccharides. Only sucrose and, to a very much lesser extent, lactose, both disaccharides, are commercial low molecular weight carbohydrates not made in this way. 

Thus, acid-catalyzed hydrolysis of sucrose initially yields D-glucose and a fmctose oxocarbonium ion, which can react with water to form D-fructose and regenerate the H+ catalyst. As a consequence, further acid degradation of sucrose can be described by the action of acids on D-glucose and D-fructose. 

The hydrolysis of sucrose catalyzed by the strongly acidic cation-exchange resin Amberlite 200C in RH form was chosen as a model reaction to compare the use of stirred tank and continuous-flow reactors [47-49], Scheme 10.6. 

Fig. 15. Effect of various concentrations of the microviscogenic agent sucrose on the PLCBc catalyzed hydrolysis of C6PC. The dashed line has a slope of one and represents data expected if an external or diffusive step were rate-determining [34]...

Quantitative measurements of simple and enzyme-catalyzed reaction rates were under way by the 1850s. In that year Wilhelmy derived first order equations for acid-catalyzed hydrolysis of sucrose which he could follow by the inversion of rotation of plane polarized light. Berthellot (1862) derived second-order equations for the rates of ester formation and, shortly after, Harcourt observed that rates of reaction doubled for each 10 °C rise in temperature. Guldberg and Waage (1864-67) demonstrated that the equilibrium of the reaction was affected by the concentration ) of the reacting substance(s). By 1877 Arrhenius had derived the definition of the equilbrium constant for a reaction from the rate constants of the forward and backward reactions. Ostwald in 1884 showed that sucrose and ester hydrolyses were affected by H+ concentration (pH). 

This method was the first accurate spectroscopic method for determining chemical reaction rates. In the mid-eighteenth century, kinetic measurements of changes in the rotation of plane polarized light upon acid-catalyzed hydrolysis of sucrose led to the concept of a dynamic equilibrium. 

A final example is the work of Wolfram and Shafizadeh1 8 on the structure of sucrose, for which Hudson had given an a-D configuration for the o-glucopyranosyl moiety, based on the results of invertase-catalyzed hydrolysis. These workers,128 using data from the methyl n-fructofuranosides, demonstrated that this hydrolysis is not accompanied by a Walden inversion and that the original work of Hudson was correct. 

The results of the experimental study and mathematical modeling of the invertase-catalyzed hydrolysis of sucrose are displayed in Fig. 8. The analysis of the output substrate concentration showed substantial substrate conversion. Therefore, the data were treated by differential equations (26) and (30), whereas the kinetic parameters were fitted using nonlinear regression. Regardless of the good agreement of the calculated and experimental values, it was concluded on the basis of a comparison of kinetic parameters obtained with those known from previous works on similar preparations of immobilized invertase [30] that this method did not provide reliable results. 

Sucrose plays a central role in plant growth and development. Invertase-catalyzed hydrolysis of sucrose is associated with the respiration required for plant growth, whereas sucrose synthase-catalyzed hydrolysis is linked to cell wall or other storage product biosynthesis. Cellulose is synthesized from UDP-glucose using cellulose synthase in membranes. Cellulose protects plant cells from the environment and provides them with a firm structure to access sunlight. 

The homogenous acid catalyzed hydrolysis of sucrose uses food approved mineral acids (sulfuric acid, hydrochloric acid) at elevated temperature. The degree of inversion could be adjusted by the point of neutralization (sodium or potassium hydroxide). This step leads inevitably to the formation of the respective salts, thereby causing high ash contents in the product. A further disadvantage of this method is the applied elevated temperature in combination with the low pH, thus causing by-product formation. 

Changes in optical rotation have been popular with those investigating glycoside hydrolysis since Wilhemy in 1850, using the newly invented polarimeter, demonstrated that hydrolysis of glycosides follows the first-order rate equation, k = 1/t log a/(a — x). Rate constants were then ob-tmned for the acid-catalyzed hydrolysis of salicin, - starch, maltose, lactose, methyl a- and /9-n-glucopyranoside, methyl a- and /S-n-galacto-pyranoside, - sucrose, and raffinose. ... 

Hydrolysis of pyranosides follows the trend observed for other compounds where the hydrolysis proceeds through an A-1 mechanism having positive AS values. Overend and coworkers calculated AS values at 60° for the hydrolysis of 24 pyranosides. All are positive, ranging from -f 4.1 to -1-23.0 cal. mole deg. all but two are greater than -f 10.0 cal. mole deg., and the mean is - - 13.7 cal. mole deg. h They compared their values with those reported for the acid-catalyzed hydrolysis at 25° of sucrose (- -7.9), ethyl orthoformate (-f5.8), and ethylal (diethoxy-methane) (-f-7.3), aU of which are known to proceed by the A-1 mechanism, and with the values calculated by Capon and Overend from the results of Heidt and Purves for the hydrolysis of methyl, benzyl, and phenyl a- and /3-n-glucopyranosides (mean, - -13.6). Many other values in the same range have been reported and are listed in Section VI (see pp. 91-100). 

In application, consider the hydrolysis of sucrose catalyzed by aqueous HCl. This is a single phase reaction with no volume change experimental data are given in... 

Although there were a number of kinetic studies of the acid-catalyzed hydrolysis of sucrose (containing a ketofuranoside) [35-38] and of methyl and benzyl fructofuranoside [39], the first systematic kinetic and mechanistic study of acid-catalyzed hydrolysis of glycofuranosides was reported by Capon and Thacker [40] (see Table 3.8). 

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