D-Mannuronic acid

M = D — mannuronic acid G = L — guluronic acid MM and GG indicate M- and G-block regions MG indicates alternating regions. 

Synthesis of Uronic Acids. Part III. d-Mannuronic Acid, M. Stacey and P. I. Wilson, J. Chem. Soc., (1944)587-588. 

Pneumococcus, polysaccharides from, 6-7 Poly(a-L-guluronic acid), 353, 355-356,415 Poly(P-D-mannuronic acid), 353-354,414 Polysaccharides, 311 -439 amino sugar derivatives, 166 chemical repeating units, 321, 324-325... 

Three routes to the synthesis of D-mannuronic acid (XLIII) are now known. The first42 was based on the original method of Fischer and Piloty48 and involved the reduction of D-mannosaccharodilactone (XLII) with sodium amalgam. The second44 utilized methyl 2,3-isopropyli-dene-a-D-mannoside (XLIV) which was oxidized at C6 with alkaline potassium permanganate to methyl isopropylidene-a-D-mannuronoside ... 

Figure 2.27 Alginate which is a copolymer of D-mannuronic acid and L-...

In model experiments,205 it was found that concentration of an aqueous solution of the aldonic acids in the presence of hydrochloric acid gives exclusively the 1,4-lactones, which, on subsequent trimethyl-silylation, give only one peak on the chromatogram. This method was successfully employed for the separation of D-galacturonic, D-glucuronic, and D-mannuronic acids. Of the 1,4-lactones examined, only the trimethylsilyl ether of D-mannono-1,4-lactone was obtained in crystalline form. However, all of the derivatives showed characteristic differences in their infrared spectra in the range of 1500 to 600 cm"1. When this method was applied to the determination of uronic acids in a variety of polysaccharides,205 it was impossible to find any hydrolytic conditions under which the uronic acids were quantitatively released and then reduced, a problem experienced by other workers.20 The method was, however, successful in affording a qualitative, microscale procedure for the identification of hexuronic acids (which otherwise are difficult to detect). 

This procedure was subsequently used by Adams and coworkers to demonstrate the presence of D-glucuronic and D-mannuronic acids... 

A variety of organic adhesives which are capable of forming strong bonds between a polymeric (acrylate) restoration and the hydrophilic tooth material have recently been developed. A number of these monomers, which possess a pendent ionizable group, are polymerized in the mouth to form an adhesive layer. Alginates, which are used as impression materials, are formed by the reaction of the sodium salt of anhydro-beta-d-mannuronic acid with calcium sulfate. Calcium ions crosslink the linear polymer to form a gel. This reaction is carried out inside the mouth, and the gel formed retains the shape of the oral cavity. 

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