Amide-Linked Carbohydrate Polymers

Whereas the above examples start from CAAs, the construction of amide-linked polymers was also possible in a Nylon type condensation using sugar diamines derived from anhydroalditols [47] or hexoses [48] and dicarboxylic acids as building blocks. For example, methyl 2,6-diamino-2,6-dideoxy-a-D-glucopyranoside (49) was 

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The carboxylic acids and amines link to form peptide bonds, also known as amide groups. Proteins are the condensation polymers made from amino acid monomers. Carbohydrates are also condensation polymers made from sugar monomers such as glucose and galactose. Condensation polymerization is occasionally used to form simple hydrocarbons. This method, however, is expensive and inefficient, so the addition polymer of ethene, i.e., polyethylene, is generally used. Condensation polymers, unlike addition polymers, may be biodegradable. The peptide or ester bonds between monomers can be hydrolyzed by acid catalysts or bacterial enzymes breaking the polymer chain into smaller pieces. The most commonly known condensation polymers are proteins and fabrics such as nylon, silk, or polyester. 

Proteins and DNAs are linear polymers where a limited set of residues are joined together by, respectively, the amide or phosphodiester bonds. The situation is similar for carbohydrates though the linking options are more varied. 

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