Sorbitol mechanism

The apparent acid strength of boric acid is increased both by strong electrolytes that modify the stmcture and activity of the solvent water and by reagents that form complexes with B(OH) 4 and/or polyborate anions. More than one mechanism may be operative when salts of metal ions are involved. In the presence of excess calcium chloride the strength of boric acid becomes comparable to that of carboxyUc acids, and such solutions maybe titrated using strong base to a sharp phenolphthalein end point. Normally titrations of boric acid are carried out following addition of mannitol or sorbitol, which form stable chelate complexes with B(OH) 4 in a manner typical of polyhydroxy compounds. EquiUbria of the type ... 

Zentner and coworkers [24,26] utilized this information in their development of a system that releases this drug over a 24 hr period. The use of NaCl to modulate the release of diltiazem presents an interesting problem in that the concentration of the solubility modifier must be maintained within certain limits and below its saturation solubility within the device. To solve this problem, core formulations were developed that contained both free and encapsulated NaCl. The encapsulated NaCl was prepared by placing a microporous coating of cellulose acetate butyrate containing 20 wt% sorbitol onto sieved NaCl crystals. The coated granules released NaCl over 12-14 hr period via an osmotic mechanism into either water or the core tablet formulation. The in vitro release profile for tablets (core I devices) containing 360 mg of diltiazem HC1 and 100 mg of NaCl equally divided between the immediate release and controlled release fractions... 

As described above, understanding the mechanism of the dispersion increase is a difficult task. In this work we compare a catalyst prepared by cobalt nitrate impregnation onto alumina with one modified by the addition of mannitol, and use TGA and in situ microscopy to investigate the increased dispersion. Mannitol is a sugar alcohol that is structurally similar to sorbitol [31], as shown in Figure 1.1. 

The same mechanism accounts for the cataracts in diabetics because aldose reductase also converts glucose to sorbitol, which causes osmotic damage. 

It has long been recognized that boron is required by higher plants [61, 62], and recent research indicates the involvement of boron in three main aspects of plant physiology cell wall structure, membrane function, and reproduction. In vascular plants, boron in solution moves in the transpiration stream from the roots and accumulates in the stems and leaves. Once in the leaves, the translocation of boron is limited and requires a phloem transport mechanism. The nature of this mechanism was only recently elucidated with the isolation of a number of borate polyol compounds from various plants [63-65]. These include sorbitol-borate ester complexes isolated from the floral nectar of peaches and mannitol-borate ester complexes from the phloem sap of celery. The implication is that the movement of boron in plants depends on borate-polyol ester formation with the particular sugar polyol compounds used as transport molecules in specific plants. 

A number of other studies have also shown that altering the physical, physicochemical, and mechanical properties of the material [7,26,27,40] can improve various sorbitol characteristics. Improvements in tableting characteristics, compressibility, and texture have been obtained by modifying the morphology and solid properties of the sorbitol powders. 

Sweet Taste. The mechanism of sweetness perception has been extensively studied because of its commercial importance. Many substances that vary in chemical structure have been discovered which are similar to the taste of sucrose. Commercial sweeteners include sucralose, acesulfame-K, saccharin, aspartame, cyclamate (Canada) and the protein thaumatin 4), Each sweetener is unique in its perceived sensation because of the time to the onset of sweetness and to maximum sweetness, ability to mask other sensations, persistence, aftertaste and intensity relative to sucrose [TABLE IT. For example, the saccharides, sorbitol and... 

Additional tests with ammonium compounds were performed to address the effect of ammonium ion (see Fig. 8). It is clear that the catalyst inhibition was not based only on the presence of ammonium ion. Ammonium carbonate showed the largest inhibition of the glucose hydrogenation reaction, while chloride and hydroxide had lesser effects. Ammonium nitrate caused no apparent inhibition on glucose conversion. A similar lack of effect was shown with potassium nitrate. In the case of ammonium nitrate, the glucose conversion mechanism was affected, so that the sorbitol yield was reduced by about 20%, but numerous byproducts and overreaction products (lower molecular weight polyols) were evident. 

The use of polyols such as pentaerythritol, mannitol, or sorbitol as classical char formers in intumescent formulations for thermoplastics is associated with migration and water solubility problems. Moreover, these additives are often not compatible with the polymeric matrix and the mechanical properties of the formulations are then very poor. Those problems can be solved (at least partially) by the synthesis of additives that concentrate the three intumescent FR elements in one material, as suggested by the pioneering work of Halpern.29 b-MAP (4) (melamine salt of 3,9-dihydroxy-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5,5]-undecane-3,9-dioxide) and Melabis (5) (melamine salt of bis(l-oxo-2,6,7-trioxa-l-phosphabicyclo[2.2.2]octan-4-ylmethanol)phosphate) were synthesized from pentaerythritol (2), melamine (3), and phosphoryl trichloride (1) (Figure 6.4). They were found to be more effective to fire retard PP than standard halogen-antimony FR. 

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