Sucrose molecular structure

Substituent effect, additivity of, 570 electrophilic aromatic substitution and, 560-563 summary of. 569 Substitution reaction, 138 Substrate (enzyme), 1041 Succinic acid, structure of, 753 Sucralose, structure of. 1006 sweetness of, 1005 Sucrose, molecular model of. 999 specific rotation of, 296 structure of, 999 sweetness of, 1005 Sugar, complex, 974 d, 980 L, 980... 

Table sugar, sec Sucrose Tagatose, structure of, 975 Talose. configuration of, 982 Tamiflu, molecular model of, 130 Tamoxifen, synthesis of, 744 Till] DNA polymerase, PCR and, 1117 Tartaric acid, stereoisomers of, 305-306... 

Figure 13.17.1 The molecular structure of sucrose, a disaccharide of glucose and fructose. Asterisks indicate the hydroxyl groups replaced with chlorine atoms in the synthetic sweetner.

Rooney et al (45) reported that the rate of carbonyl formation varied with the molecular structure of sugar. Xylose was most reactive as it produced the greatest quantity of carbonyls, followed by glucose, then maltose. In the presence of these sugars isoleucine was more reactive than phenylalanine. In a study on the Strecker degradation of valine-carbonyl, diacetyl showed the greatest reactivity followed by sorbose> arabinose>xylose>fructose>glucose>sucrose>rhamnose, Self(46). 

L-Sucrose tastes sweet, but it is not metabolized. It has been suggested as a potential nonnutritive sweetener. Draw the molecular structure of L-sucrose, using Figure 23.16b as a starting point. 

Sugar hydrolysis and brovming occurred during heat treatment at 70°C, and developed faster in sucrose samples containing MgCl2 (Figure 54.1 and Figure 54.2). It is well known that trehalose is very stable to hydrolysis, and sucrose hydrolysis occurs much faster because of its molecular structure... 

Take a look at Figure 13.16. It shows the molecular structure of a sucrose molecule. Notice that the structure has a number of O—H bonds. As you learned earher, if a molecule contains O—H bonds, it will tend to be polar and it can form hydrogen bonds. One of the reasons that sugar is a solid rather than a liquid at room temperature is that sugar molecules have the ability to form hydrogen bonds with each other. The attractions hold the molecules in a crystal arrangement that ordinarily cannot be broken without an input of heat. 

As the table shows, aspartame, the popular artificial sweetener in soft drinks, is 160 times sweeter than sucrose, common table sugar. The sweetening ability of aspartame comes from a molecular structure that creates an impact 160 times that of sucrose on your taste buds that detect the sweet taste. 

The deposited thin films of Sucrose were investigated by FTIR spectrometry with the aim to obtain first information about their molecular structure as compared to the powder material (sample S) used for the targets preparation (Fig. 1). The IR spectra for S and SI samples show the vibration modes of sucrose. In these spectra... 

Fig. 3.—Comparison of Molecular Structures of Sucrose in Two Crystals. (View in each case is in plane of C -2, 0 -2, and C -5, perpendicular to bond O-2-C -2.) (Courtesy of Drs. G. M. Brown and H. A. Levy.)...

Figure 1. Molecular structures of sucrose and FDA-approved artificial sweetners.

For a molecule to taste sweet, it must fit into a taste bud site where a nerve impulse can carry the message of sweetness from the tongue to the brain. Not all natural sugars, however, trigger an equivalent neural response. Some sugars, such as glucose, have a relatively bland taste, and others, such as fructose, taste very sweet. Fructose, in fact, has a sweeter taste than common table sugar or sucrose. Furthermore, individuals vary in their ability to perceive sweet substances. The relationship between perceived sweetness and molecular structure is very complicated, and, to date, it is rather poorly understood. 

The measurement of pH is further complicated by the effect of high concentrations of sucrose (e.g., 60 Brix or 60%w/w) on hydrogen ion activity. Clarke (1970) has discussed the effect of sucrose solution structure on pH and calcium ion electrode processes and shown a decreased response of these electrodes to changes in ionic activity in sucrose solutions at 60 Brix and 24 °C. This reduced electrode response can in part be explained by the structural order of the sucrose-water mixture (molecular association in sucrose-water systems has been reviewed by Allen et at. (1974). In a 60 Brix sucrose solution the ratio of water molecules to sucrose molecules is 12.7 1, with water molecules hydrogen-bonded to sucrose (/.e., in the solvation shell) in dynamic equilibrium with free water. Therefore, the concentration of free water molecules and dissociated ions is much less than in dilute sucrose solutions. The number of water molecules in the sucrose solvation... 

---