Names | |
---|---|
IUPAC name 3-Deoxy-2-C-(hydroxymethyl)-D-erythro-pentonic acid | |
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 | |
Identifiers | |
3D model (JSmol) | |
ChemSpider | |
PubChem CID | |
UNII | |
CompTox Dashboard (EPA) | |
| |
| |
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). |
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]
Since 1993, the diastereomers of isosaccharinic acid have received particular attention in the literature due to its ability to complex a range of radionuclides, potentially affecting their migration. [5] [6] [7] ISA is formed as a result of interactions between cellulosic materials present within the intermediate level waste inventory various countries and the alkalinity resulting from the use of cementitious materials in the construction of a deep geological repository. [8] Greenfield et al. (1993), have discovered that ISA and constituents formed in a cellulose degradation leachate were capable of forming soluble complexes with thorium, uranium (IV) and plutonium. [9] [5] [10] In the case of plutonium, ISA concentrations higher than 10−5 M were capable of increasing solubility above pH 12.0, where concentrations of 1-5 × 10−3 M were found to increase the solubility by an order of magnitude from 10−5 to 10−4 M. Allard et al. (2006) found that a concentration of ISA of 2 × 10−3 M could increase plutonium solubility by a factor of 2 × 105. [11] In addition a range of studies on the complexation properties of α-isosaccharinic acid in alkaline solutions with various metals of different valence, including nickel (II), europium (III), americium (III) and thorium (IV), have been conducted. [12] [13] [14] [15] [16]
Vercammen et al. (2001) showed that although Ca(α-ISA)2 is sparingly soluble, [17] both europium (III) and thorium (IV) were capable of forming soluble complexes with ISA between pH 10.7 and 13.3, where a mixed metal complex was observed in the presence of thorium. [12] Wieland et al. (2002) also observed that α-ISA prevented the uptake of thorium by hardened cement pastes. [15] Warwick et al. (2003) have also shown that ISA is capable of influencing the solubility of both uranium and nickel through complexation. [13] [14] Tits et al. (2005) observed that in the absence of ISA, europium, americium and thorium will sorb onto calcite aggregates present in concrete within an ILW GDF. [16] Should ISA concentrations within the disposal facility exceed 10−5 mol L−1 (2 × 10−5 mol L−1 in the case of Th(IV)), it was reported that the sorption onto calcite would be significantly affected such that the radionuclides studied would no longer be sorbed to the cement and instead be complexed by ISA.
The effect of cellulose degradation products on radionuclide solubility and sorption is the subject of a study from 2013. [18] Cellulose degradation product leachates were first produced by contacting cellulose sources (wood, rad wipes or cotton wool) with calcium hydroxide (pH 12.7) under anaerobic conditions. Analysis of the leachates across 1 000 days suggested that the primary product of the degradation was ISA, although a range of other organic compounds were formed and varied across cellulose source. In these experiments both ISA and X-ISA were able to increase the solubility of europium at pH 12, where in experiments with thorium ISA had a more profound effect on thorium solubility than X-ISA, for which little effect was observed.
More recently, a systematic study was published on the interactions between plutonium, ISA, and cement, as well as sorption. [19] The investigation was focused on repository-like conditions, including high pH due to cementitious materials and low redox potential. The predominant species at various conditions were identified, including quaternary materials such as Ca(II)Pu(IV)(OH)3ISA–H+. The sorption of Pu on cement was found to be significantly lowered due to complexation with ISA.
ISA also represents a major carbon source within a geological disposal facility (GDF) since it comprises >70% of cellulose degradation products as a result of alkaline hydrolysis. The high pH associated with the massive use of concrete in such a facility means that microbial activity may or may not occur within the alkaline disturbed zone depending on the local microbial consortia intruding upon or surrounding such a facility in the post closure phase. [20] Initial studies have shown that both alpha and beta forms of ISA are readily available for microbial activity under the anaerobic conditions expected within the far field of a disposal facility or within ungrouted waste packages. [21] Since the pH of pore water within the near field of a disposal facility is expected to fall from 13.5 to 12.5 − 10 over tens of thousands of years, the ability of micro-organisms to adapt to these alkaline pH values has also been investigated. Mesophilic consortia have been shown to adapt to a pH of 10 within a number of weeks, ISA degradation ceased above pH 11.0. [22] Microbial consortia from hyperalkaline environments in which exposure to pH > 11.0 has occurred for over a century have also been exposed to ISA generated from the alkaline hydrolysis of organic matter in situ. This consortia was readily capable of degrading ISA. [23] It can also exist as polymicrobial flocculates, which has shown to be able of survival up to pH 12.5. [24] As a result, the impact of microbial activity within a GDF is expected to be through the degradation of ISA's and production of gas, which may create overpressure but also through the generation of 14C bearing gases. [25]
In chemistry, a silicate is any member of a family of polyatomic anions consisting of silicon and oxygen, usually with the general formula [SiO(4-2x)−
4−x]
n, where 0 ≤ x < 2. The family includes orthosilicate SiO4−4, metasilicate SiO2−3, and pyrosilicate Si2O6−7. The name is also used for any salt of such anions, such as sodium metasilicate; or any ester containing the corresponding chemical group, such as tetramethyl orthosilicate. The name "silicate" is sometimes extended to any anions containing silicon, even if they do not fit the general formula or contain other atoms besides oxygen; such as hexafluorosilicate [SiF6]2−.Most commonly, silicates are encountered as silicate minerals.
Calcium carbonate is a chemical compound with the chemical formula CaCO3. It is a common substance found in rocks as the minerals calcite and aragonite, most notably in chalk and limestone, eggshells, gastropod shells, shellfish skeletons and pearls. Materials containing much calcium carbonate or resembling it are described as calcareous. Calcium carbonate is the active ingredient in agricultural lime and is produced when calcium ions in hard water react with carbonate ions to form limescale. It has medical use as a calcium supplement or as an antacid, but excessive consumption can be hazardous and cause hypercalcemia and digestive issues.
Ethylenediaminetetraacetic acid (EDTA), also called edetic acid after its own abbreviation, is an aminopolycarboxylic acid with the formula [CH2N(CH2CO2H)2]2. This white, water-soluble solid is widely used to bind to iron (Fe2+/Fe3+) and calcium ions (Ca2+), forming water-soluble complexes even at neutral pH. It is thus used to dissolve Fe- and Ca-containing scale as well as to deliver iron ions under conditions where its oxides are insoluble. EDTA is available as several salts, notably disodium EDTA, sodium calcium edetate, and tetrasodium EDTA, but these all function similarly.
Lignin is a class of complex organic polymers that form key structural materials in the support tissues of most plants. Lignins are particularly important in the formation of cell walls, especially in wood and bark, because they lend rigidity and do not rot easily. Chemically, lignins are polymers made by cross-linking phenolic precursors.
Calcium hydroxide (traditionally called slaked lime) is an inorganic compound with the chemical formula Ca(OH)2. It is a colorless crystal or white powder and is produced when quicklime (calcium oxide) is mixed with water. It has many names including hydrated lime, caustic lime, builders' lime, slaked lime, cal, and pickling lime. Calcium hydroxide is used in many applications, including food preparation, where it has been identified as E number E526. Limewater, also called milk of lime, is the common name for a saturated solution of calcium hydroxide.
Anthraquinone, also called anthracenedione or dioxoanthracene, is an aromatic organic compound with formula C
14H
8O
2. Isomers include various quinone derivatives. The term anthraquinone however refers to the isomer, 9,10-anthraquinone wherein the keto groups are located on the central ring. It is a building block of many dyes and is used in bleaching pulp for papermaking. It is a yellow, highly crystalline solid, poorly soluble in water but soluble in hot organic solvents. It is almost completely insoluble in ethanol near room temperature but 2.25 g will dissolve in 100 g of boiling ethanol. It is found in nature as the rare mineral hoelite.
Humic substances (HS) are coloured recalcitrant organic compounds naturally formed during long-term decomposition and transformation of biomass residues. The colour of humic substances varies from yellow to brown to black. Humic substances represent the major part of organic matter in soil, peat, coal and sediments and are important components of dissolved natural organic matter (NOM) in lakes, rivers and sea water.
Gluconic acid is an organic compound with molecular formula C6H12O7 and condensed structural formula HOCH2(CHOH)4CO2H. A white solid, it is forms the gluconate anion in neutral aqueous solution. The salts of gluconic acid are known as "gluconates". Gluconic acid, gluconate salts, and gluconate esters occur widely in nature because such species arise from the oxidation of glucose. Some drugs are injected in the form of gluconates.
Murexide (NH4C8H4N5O6, or C8H5N5O6·NH3), also called ammonium purpurate or MX, is the ammonium salt of purpuric acid. It is a purple solid that is soluble in water. The compound was once used as an indicator reagent. Aqueous solutions are yellow at low pH, reddish-purple in weakly acidic solutions, and blue-purple in alkaline solutions.
Pentetic acid or diethylenetriaminepentaacetic acid (DTPA) is an aminopolycarboxylic acid consisting of a diethylenetriamine backbone with five carboxymethyl groups. The molecule can be viewed as an expanded version of EDTA and is used similarly. It is a white solid with limited solubility in water.
The alkali–silica reaction (ASR), also commonly known as concrete cancer, is a deleterious swelling reaction that occurs over time in concrete between the highly alkaline cement paste and the reactive amorphous silica found in many common aggregates, given sufficient moisture.
The sulfite process produces wood pulp that is almost pure cellulose fibers by treating wood chips with solutions of sulfite and bisulfite ions. These chemicals cleave the bonds between the cellulose and lignin components of the lignocellulose. A variety of sulfite/bisulfite salts are used, including sodium (Na+), calcium (Ca2+), potassium (K+), magnesium (Mg2+), and ammonium (NH4+). The lignin is converted to lignosulfonates, which are soluble and can be separated from the cellulose fibers. For the production of cellulose, the sulfite process competes with the Kraft process which produces stronger fibers and is less environmentally costly.
Dipicolinic acid is a chemical compound which plays a role in the heat resistance of bacterial endospores. It is also used to prepare dipicolinato ligated lanthanide and transition metal complexes for ion chromatography.
Concrete degradation may have many different causes. Concrete is mostly damaged by the corrosion of reinforcement bars due to the carbonatation of hardened cement paste or chloride attack under wet conditions. Chemical damages are caused by the formation of expansive products produced by various chemical reactions, by aggressive chemical species present in groundwater and seawater, or by microorganisms. Other damaging processes can also involve calcium leaching by water infiltration and different physical phenomena initiating cracks formation and propagation. All these detrimental processes and damaging agents adversely affects the concrete mechanical strength and its durability.
Microbiologically induced calcium carbonate precipitation (MICP) is a bio-geochemical process that induces calcium carbonate precipitation within the soil matrix. Biomineralization in the form of calcium carbonate precipitation can be traced back to the Precambrian period. Calcium carbonate can be precipitated in three polymorphic forms, which in the order of their usual stabilities are calcite, aragonite and vaterite. The main groups of microorganisms that can induce the carbonate precipitation are photosynthetic microorganisms such as cyanobacteria and microalgae; sulfate-reducing bacteria; and some species of microorganisms involved in nitrogen cycle. Several mechanisms have been identified by which bacteria can induce the calcium carbonate precipitation, including urea hydrolysis, denitrification, sulfate production, and iron reduction. Two different pathways, or autotrophic and heterotrophic pathways, through which calcium carbonate is produced have been identified. There are three autotrophic pathways, which all result in depletion of carbon dioxide and favouring calcium carbonate precipitation. In heterotrophic pathway, two metabolic cycles can be involved: the nitrogen cycle and the sulfur cycle. Several applications of this process have been proposed, such as remediation of cracks and corrosion prevention in concrete, biogrout, sequestration of radionuclides and heavy metals.
Many compounds of thorium are known: this is because thorium and uranium are the most stable and accessible actinides and are the only actinides that can be studied safely and legally in bulk in a normal laboratory. As such, they have the best-known chemistry of the actinides, along with that of plutonium, as the self-heating and radiation from them is not enough to cause radiolysis of chemical bonds as it is for the other actinides. While the later actinides from americium onwards are predominantly trivalent and behave more similarly to the corresponding lanthanides, as one would expect from periodic trends, the early actinides up to plutonium have relativistically destabilised and hence delocalised 5f and 6d electrons that participate in chemistry in a similar way to the early transition metals of group 3 through 8: thus, all their valence electrons can participate in chemical reactions, although this is not common for neptunium and plutonium.
Thulium(III) nitrate is an inorganic compound, a salt of thulium and nitric acid with the chemical formula Tm(NO3)3. The compound forms dark-green crystals, readily soluble in water, also forms crystalline hydrates.
Neodymium acetate is an inorganic salt composed of a neodymium atom trication and three acetate groups as anions where neodymium exhibits the +3 oxidation state. It has a chemical formula of Nd(CH3COO)3 although it can be informally referred to as NdAc because Ac is an informal symbol for acetate. It commonly occurs as a light purple powder.
Tacharanite is a calcium aluminium silicate hydrate (C-A-S-H) mineral of general chemical formula Ca12Al2Si18O33(OH)36 with some resemblance to the calcium silicate hydrate (C-S-H) mineral tobermorite. It is often found in mineral assemblage with zeolites and other hydrated calcium silicates.
AFt Phases refer to the calcium Aluminate Ferrite trisubstituted, or calcium aluminate trisubstituted, phases present in hydrated cement paste (HCP) in concrete.