Randomly methylated P-cyclodextrin

We begin with an excerpt from Environmental Science Technology (excerpt 4B). In a combined R D section, the authors tell us what happened when they coated different types of soil with randomly methylated P-cyclodextrins (RAMEB). Cyclodextrins are highly water-soluble, crystalline sugars their shape (referred to as toroidal) resembles a water pail without a bottom. The outer surfaces of the pail are hydrophilic (water-loving), which accounts for their solubility in water and their ability to attract water molecules. RAMEB alone adsorbs water molecules hence, the authors predicted that RAMEB-coated soils would adsorb more water than their noncoated counterparts. 

Let s begin with the excerpt on randomly methylated P-cyclodextrin (RAMEB)-enriched soils in chapter 4 (excerpt 4B). The authors use an iterative R D approach They state their first result (Rl), pertaining to clay-rich soils, and then immediately offer an interpretation (Dl) of that result. This is followed by a result and interpretation for clay-poor soils (R2D2) and a result and interpretation for medium-clay-content soils (R3D3). Thus, the result-discussion sequence is iterated three times. In each case, the discussion immediately follows the result hence, submove 1.1 (which reminds readers of the result) is not needed. 

P16 Two CD derivatives are most commonly used for soil remediation hydroxypropyl and random methylated P-cyclodextrins (HPBCD and... 

Jozefaciuk, G. Muranyi, A. Fenyvesi, E. Effect of Randomly Methylated P-Cyclodextrin on Physical Properties of Soils. Environ. Sci. Technol 2003, 37, 3012-3017. 

Many CDs have been successfully used to solubilize insoluble drugs, here are a partial list of CD derivatives reported in the literature fflFCD, SBE-ft-CDs, randomly methylated-P-cyclodextrin (RM-p-CD), 2,3,6-partially methylat flcyclodextrin (PM-ft-CD), glucosyl-ft-CD (G1-P-CD), maltosyl-p-cyclodextrin (G2- -CD), hydroxyethyl-p-cyclodextrin (He-p-CD), diethyl-P-cyclodextrin (DE-p-CD)P-carboxymethyl-Qethyl- -cyclodextrin (CME-p-CD), and (2,6-oG>-methyl)-p-cyclodextrin (DOM-p-CD). 

Among the cyclodextrins, the use of DMpCD was shown to have the highest effect on the transnasal bioavailability of insulin in rats. Several studies reported on their concentration-dependent effect. Besides for peptides, the methylated p-cyclodextrins have shown to be useful in nasal delivery of lipophilic drugs. The toxicological profile of dimethyl p-cyclo-dextrins and of randomly methylated p-cyclodextrins appeared excellent. Attention should be paid, if possible, onbioavailability differences between animal and human models. 

Ruthenium on charcoal and randomly methylated p-cyclodextrin has been used as a recyclable catalyst system to form Qxs in water from benzoin and 1,2-diamines (Scheme 2.12) [88]. Molecular oxygen has been used perhaps to facilitate in situ formation of the 1,2-diketone from the benzoin and the final delydrogenation. 

As Monflier and coworkers [48] have shown, the rhodium-catalyzed hydroformylation of triglycerides in water pressure can be supported by the addition of randomly methylated P-cyclodextrines (RAME-P-CDs). Syngas pressure (20-80 bar), temperature (50-80 °C), nature of the sulfonated phosphine ligand, and the amount of R AME-P-CD had a profound influence of the catalytic results. 

Because the CDs possess hydrophobic inner surfaces and hydrophilic outer surfaces, they include hydrophobic molecules corresponding to their cavity sizes due to hydrophobic interactions. Thus, the CDs are well-known host molecules that increase the solubilities of hydrophobic guest molecules in water by the formation of host-guest complexes. Since p-CD has a low solubility in water compared to the a- and y-CDs, 2,6-dimethyl-P-cyclodextrin (Me2-P-CD) and randomly methylated P-cyclodextrin (RM-P-CD) have been used in many cases (Figure 5.3). 

Chemical modification of cyclodextrins is achieved through reactions of their hydroxyl groups. Of the 21 hydroxyls ofP-CD, the seven primary ones (C-6) can easily be reacted. In addition, the C-2 secondary hydroxyl groups are also fairly reactive while the ones at C-3 resist modification (e.g. by methylation). Several CD derivatives are available commercially in large quantities including -among others- randomly methylated P-cylodextrin and hydroxypropyl-P-cylodextrin [2]. Chemical modifications substantially alter the solubility of cyclodextrins in water. For example, the solubility of P-CD... 

Subsequently, a series of modified cyclodextrins were demonstrated to be effective for the hydroformylation of higher olefins [39], For example, combined with the sulfonated Xantphos 3, randomly methylated a- or p-cyclodextrin (RAME-a-CD or RAME-P-CD) provided an enhanced rate and n/iso ratio for the hydroformylation of 1-octene, allowing for a 74% conversion (99% selectivity) and n/iso ratio of 33 when using RAME-a-CD and 90% conversion (>99% selectivity) and an n/iso ratio of 20 when using RAME-P-CD. In contrast, Rh-3 alone led to 19% conversion (94% selectivity) and an n/iso ratio of 14 [40]. 

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