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Isosaccharinic acid
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| Names | |
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| IUPAC name
3-Deoxy-2-C-(hydroxymethyl)-D-erythro-pentonic acid
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| Systematic IUPAC name
(2S,4S)-2,4,5-Trihydroxy-2-(hydroxymethyl)pentanoic acid | |
| Other names
D-gluco-Isosaccharinic acid; Isosaccharinic acid; α-D-Glucoisosaccharinic acid; α-D-Isosaccharinic acid; α-Glucoisosaccharinic acid; α-Isosaccharinic acid
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| Identifiers | |
3D model (JSmol)
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| ChemSpider | |
PubChem CID
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| UNII | |
CompTox Dashboard (EPA)
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| Properties | |
| C6H12O6 | |
| Molar mass | 180.156 g·mol−1 |
| Melting point | 189 to 194 °C (372 to 381 °F; 462 to 467 K)[1] |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Isosaccharinic acid (ISA) is a six-carbon sugar acid which is formed by the action of calcium hydroxide on lactose and other carbohydrates. It is of interest because it may form in intermediate-level nuclear waste stores when cellulose is degraded by the calcium hydroxide in cements such as Portland cement. The calcium salt of the alpha form of ISA is very crystalline and quite insoluble in cold water, but in hot water it is soluble.
ISA is thought to form by means of a series of reactions in which calcium ions acting as lewis acids catalyze two of the three steps. The first step is likely to be a rearrangement of the reducing sugar end of the cellulose (or lactose) into a keto sugar, the second step is likely to be a reaction similar to the base catalyzed dehydration which often occurs after an aldol reaction. In this second step an alkoxide (derived from a sugar) takes the role of the hydroxide leaving group, this second step is not likely to require the lewis acidity of the calcium. The final step is a benzilic acid rearrangement from a 1,2-diketone (1,5,6-trihydroxyhexane-2,3-dione) which is formed from the carbohydrate.[2]
Under acidic conditions sugars tend to form furans such as furfural and 5-hydroxymethylfurfural by a series of dehydrations of the carbohydrate.
In acidic solutions the acid tends to form a 5-membered ring (lactone) by forming an ester between the carboxylic acid group and one of the alcohols. When treated under anhydrous conditions with acetone, an acid and a dehydration agent two of the alcohol groups can be protected as a cyclic acetone acetal thus leaving behind only one alcohol,[3] prolonged treatment with 2,2-dimethoxypropane forms a protected form of ISA where all four of the alcohol groups are protected as acetone acetals and the carboxylic acid is in the form of the methyl ester.[4] These protected forms of ISA have been used as a starting material for chiral organic compounds anthracyclines.[4][3]
- ^ Whistler, Roy L.; Richards, G. N. (1958). "Uronic acid fragments from slash pine (Pinus elliotti) and their behavior in alkaline solution". Journal of the American Chemical Society. 80 (18): 4888–4891. doi:10.1021/ja01551a031.
- ^ Whistler, Roy L.; BeMiller, J. N. (1960). "4-Deoxy-3-oxo-D-glycero-2-hexulose, the dicarbonyl intermediate in the formation of D-isosaccharinic acids1". Journal of the American Chemical Society. 82 (14): 3705–3707. doi:10.1021/ja01499a058. ISSN 0002-7863.
- ^ a b Florent, J. C.; Ughetto-Monfrin, J.; Monneret, C. (1987). "Anthracyclinones. 2. Isosaccharinic acid as chiral template for the synthesis of (+)-4-demethoxy-9-deacetyl-9-hydroxymethyldaunomycinone and (-)-4-deoxy-gamma-rhodomycinone". The Journal of Organic Chemistry. 52 (6): 1051–1056. doi:10.1021/jo00382a015. ISSN 0022-3263.
- ^ a b Florent, Jean-Claude; Génot, Agnès; Monneret, Claude (1985). "Chiral pool synthesis of tetralin as AB ring segment, precursor of anthracyclines". Tetrahedron Letters. 26 (43): 5295–5298. doi:10.1016/S0040-4039(00)95020-2. ISSN 0040-4039.
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