Sucrose, inversion reaction

When the sucrose inversion reaction was later run in nonaqueous solvents it was recognized that a better description of the rate of disappearance of sucrose S is given by the following equations ... 

Sucrose inversion, a typical proton-catalysed irreversible reaction... 

Other results also confirm the important role of internal diffusion. Experimental activation energies (67—75 kJ mol"1) of the sucrose inversion catalysed by ion exchangers [506—509] were considerably lower than those of a homogeneously catalysed reaction (105—121 kJ mol"1) [505, 506,508] and were close to the arithmetic average of the activation energy for the chemical reaction and for the diffusion in pores. The dependence of the rate coefficient on the concentration in the resin of functional groups in the H+-form was found to be of an order lower than unity. A theoretical analysis based on the Wheeler—Thiele model for a reaction coupled with intraparticle diffusion in a spherical bead revealed [510,511] that the dependence of the experimental rate coefficient on acid group concentration should be close to those found experimentally (orders, 0.65 and 0.53 for neutralisation with Na+ and K+ ions respectively [511] or 0.5 with Na+ ions [510]). 

The basic mechanism for enzyme-catalyzed reactions was first proposed by Michaelis and Menten and confirmed by a study of the kinetics of the sucrose inversion. A simple reaction mechanism by which an enzyme converts a reactant S, usually called a substrate, into products P is... 

Acid-Catalyzed Reaction. A number of enzyme-catalyzed reactions, including the sucrose inversion to be studied in this experiment, can also be carried out under non-physiological conditions by using H ions as a less efficient catalyst. In the present case, the acid-catalyzed reaction rate has the form... 

From the data of runs Cl to C20 and D1 to D20, calculate x, the number of moles of sucrose hydrolyzed in each time interval. If the reaction were zero order in sucrose, then we would expect that (x/0.003) = kf, where x/0.003 is the concentration of either of the product species in mol L units. Prepare a graph of the results obtained in these two series of runs, plotting x versus t, and indicate whether the data are consistent with the hypothesis that the reaction is zero order in sucrose. Note that, even if a reaction starts out being zero order in sucrose, this cannot continue indefinitely. Indeed, we expect the inversion reaction to become first order in sucrose when (S) becomes sufficiently small. 

A special case arises when the "skin" (membrane) layer of a normal composite membrane element is immobilized with a catalyst and not intended for separating reaction species. Consider the example of an enzyme, invertase, for the reaction of sucrose inversion. Enzyme is immobilized within a two<layer alumina membrane element by filtering an invertase solution from the porous support side. After enzyme immobilization, the sucrose solution is pumped to the skin or the support side of the membrane element in a crossflow fashion. By the action of an applied pressure difference across the element, the sucrose solution is forced to flow through the composite porous structure. Nakajima et al. [1988] found that the permeate direction of the sucrose solution has pronounced effects on the reaction rate and the degree of conversion. Higher reaction rates and conversions occur when the sucrose solution is supplied from the skin side. The effect on the reaction rate is consistently shown in Figure 11.6 for two different membrane elements membrane A is immobilized by filtering the enzyme solution from the support layer side while membrane B from the skin layer side. 

Figure 11.6 Effect of permeate direction on reaction rate of sucrose Inversion (circles refer to membrane A and triangles to membrane B open symbols are associated with permeate flow from skin layer side and filled symbols from support layer side) [Nakajimactal., 1988]...

The sucrose inversion has been extensively studied from the viewpoint of electrolyte effects (Guggenheim and Wiseman, 2), the application of the Arrhenius equation to the reaction (Leininger and Kilpatrick, 3), and the catalytic effects of acid molecules (Hammett and Paul, 4). It is probable that, in aqueous solution, we are dealing with a case of specific hydrogen ion catalysis and can postulate the equilibrium (Gross, Steiner, and Suess, 5)... 

Chromatographic batch reactors are employed to prepare instable reagents on the laboratory scale (Coca et al., 1993) and for the production of fine chemicals. These applications include the racemic resolution of amino acid esters (Kalbe et al., 1989), acid-catalyzed sucrose inversion (Lauer, 1980), production of dextran (Zafar and Barker, 1988) and saccharification of starch to maltose (Sarmidi and Barker, 1993a). Sardin et al. (1993) employed batch chromatographic reactors for different esterification reactions such as the esterification of acetic acid with ethanol and the transesterification of methylacetate. Falk and Seidel-Morgenstern (2002) have investigated the hydrolysis of methyl formate. 

The chromatographic SMB reactor has been examined for various reaction systems, with the main focus on reactions of the type A + B C + D. Examples are esterifications of acetic acid with methanol (Lode et al., 2003b), ethanol (Mazotti et al., 1996a) and (5-phenethyl alcohol (Kawase et al., 1996) as well as the production of bisphenol A (Kawase et al., 1999). The same reaction type can also be found for various hydrocarbons, such as the transfer reaction of sucrose with lactose to lactosuc-rose (Kawase et al., 2001) and the hydrolysis of lactose (Shieh and Barker, 1996). Barker et al. (1992) focused on reactions of the type A B + C, such as enzyme-catalyzed sucrose inversion and the production of dextran. Also, reactions of the type A tB have been investigated, e.g. isomerization of glucose to fructose by Fricke (2005) as well as Tuomi and Engell (2004). Michel et al. (2003) have examined the application of electrochemical SMB reactors for consecutive reactions and used as an example the production of arabinose. 

The disaccharides such as sucrose undergo inversion reaction in acid medium implying the cleavage of the C-O-C glycosidic bond. 

Inversion of Sucrose. Many hydrolytic reactions, including the decomposition of esters, are reversible but others such as sucrose inversion and protein hydrolysis, though not necessarily complete, have not been reversed. The heat effects of these reactions, however, are important. The inversion of sucrose, for example, is an exothermic reaction with AH at 25°C approximately —3.6 kg-cal per mole. ... 

The SMBR where reaction of type A B -i- C (sucrose inversion) was studied in our laboratory [32]. The sucrose is introduced in the middle of the unit with the feed stream. The reaction is catalyzed by the enzyme invertase introduced in the unit with the eluent stream. The sucrose reacts near to the feed port fructose and glucose are formed and separated in the extract and raffinate, respectively. Typical concentration profiles are shown in Fig. 3.4-15. 

A new polarlmetric method for studying reaction kinetics has been applied to sucrose inversion in the presence of acid, the results... 

Sucrose is dextro-rotatory. Fructose shows a laevo-rotation greater in magnitude than the dextro-rotation shown by glucose. Hence as the hydrolysis of sucrose proceeds, the dextro-rotation gradually falls to zero and the solution finally shows a laevo-rotation. This hydrolysis is therefore sometimes called inversion and so the enzyme which catalyses the reaction is known as " invertase. Its more systematic name is, however, sucrase. 

Reaction with Organic Compounds. Many organic reactions are catalyzed by acids such as HCl. Typical examples of the use of HCl in these processes include conversion of HgnoceUulose to hexose and pentose, sucrose to inverted sugar, esterification of aromatic acids, transformation of acetaminochlorobenzene to chloroaruHdes, and inversion of methone [1074-95-9]. 

---