Lactose, general reactions

Because of the high nucleophilicity 46 is trapped by means of fast irreversible anomeric O-alkylation and leads to 50.3 23 In general the equatorial oxygen bears the highest nucleophilicity under these reaction conditions. Accompanying the O-silyl group rearrangement and the anomeric benzylation excess NaH and benzyl bromide provides fully benzyl protected lactose derivative 9. 

Because there is such a wide selection available, rational choice of the necessary excipients and their concentration is required. Consideration must also be given to cost, reliability, availability, and international acceptability. Although generally considered inert, formulation incompatibility of excipients is also necessary. Lactose, for example, can react with primary and secondary amines via its aldehyde group by Maillaird condensation reaction [6], and calcium carbonate is incompatible with acids due to acid-base chemical reaction and with tetracyclines due to complexation. Additionally, excipients can contribute to the instability of the active substance through moisture distribution. 

We now turn to lactose, where the situation is more complicated. As mentioned, several sugars, including lactose, occur in two forms, the anomers denoted a and (3. In solution, the two are in equilibrium with each other, i.e., a (3. The equilibrium ratio varies with temperature R = [ 3]/[a] = 1.64 — 0.0027 (T —273.15). The reaction leading to equilibrium— generally called mutarotation—is rather slow, the first-order rate constant at 30°C being about 1 h. Both a-lactose, as a monohydrate, and anhydrous... 

The oxidation reaction with a carbohydrate (e.g., lactose) or with a fat or fatty acid such as oleic acid is generally quite slow. The organic compound is eventually converted to COj and H2O. The reactions are generally far too slow to be considered significant in the context of the reaction times involved in various chlorination practices. The dose-residual curves presented in Fig. 7-30 represent the slow progress of the... 

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