Use the following information to answer questions:   Cyclodextrins (CDs) are a group of naturally cyclic oligosaccharides consisting of six, seven, or eight glucose subunits connected by α-(1,4) glycosidic bonds, named α-, β-, and γ-CDs, respectively. They are shaped cylindrically, with glycosidic oxygen bridges on the inside and hydroxyl groups on the outside. CDs can form inclusion complexes with molecules whose moieties interact with their internal surfaces. A novel method was developed for the preparation of β-CD functionalized magnetic nanoparticles (MNPs) (Figure... Show more

Use the following information to answer questions:
 

Cyclodextrins (CDs) are a group of naturally cyclic oligosaccharides consisting of six, seven, or eight glucose subunits connected by α-(1,4) glycosidic bonds, named α-, β-, and γ-CDs, respectively. They are shaped cylindrically, with glycosidic oxygen bridges on the inside and hydroxyl groups on the outside. CDs can form inclusion complexes with molecules whose moieties interact with their internal surfaces.

A novel method was developed for the preparation of β-CD functionalized magnetic nanoparticles (MNPs) (Figure 1).

Monotosyl-polyethylene glycol (PEG) silane was synthesized by the route shown in Figure 2, where a PEG diol was modified to form the corresponding monotosyl-PEG, followed by reaction of the molecule with IPTS. 1H NMR and FTIR spectroscopy were used to track molecule formation after each step, ultimately confirming formation of monotosyl-PEG silane. The nanoparticles were modified with the monotosyl-PEG silane first, and then amino-β-CD units displaced the tosyl units.

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MCAT Chemical and Physical Foundations of Biological Systems 18

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4 Questions

1. The reason for the inclusion of tosyl groups in the synthesis is to

provide an effective leaving group for the ensuing nucleophilic attack.contribute a sulfur to the functionalized product.contribute an oxygen to the functionalized final product.promote reactivity at the adjacent oxygen originally on the PEG diol.

2. Moieties that are most likely to interact with CDs in inclusion complexes are

amphipathic.negatively charged.hydrophobic.positively charged.

3. Which intermediate or product in this synthesis does the FTIR spectrum below represent?

monotosyl-PEG silaneβ-CD–PEG–MNPsPEG diolOA-MNPs

4. The first reaction step in Figure 2 can be completed by reacting PEG, tosyl chloride, and

a weak acid in an SN1 reaction.a weak acid in an SN2 reaction.a weak base in an SN2 reaction.a weak base in an SN1 reaction.